Patent Grant
8684980
Using spray dispensers to administer products in the form of mists or sprays is an area with large potential for safe, easy-to-use products. The major challenge in providing such an applicator is to provide consistent and accurate delivery of suitable doses.
An important area where spray applicators are needed is in delivery of eye medications. The application of fluids, as in the case of eye drops has always posed a problem, especially for children and animals who tend to blink or jerk at the critical moment, causing the droplet to land on the eyelid, nose or other part of the face. The impact of a large drop of fluid on the eyeball, especially when the fluid is at a different temperature also tends to produce a blinking reaction. Elderly also often lose the hand coordination necessary to get the eye drops into their eyes. Stroke victims have similar difficulties. Dropper delivery often requires a particular physical position, such as tilting of the head or a horizontal position. Neither might be practical.
Often, it is critical that the subject administer the correct dose the requisite number of times per day. However, in practice, subjects that are prescribed eye medications for home use tend to forget to dose, or dose excessively or cross-dose with other medications. One of the major compliance problems is that, even if the subject is intent on following the treatment regimen, he or she often forgets to dose.
Currently, many of these medications are administered by eye droppers. Current eye drop devices often either require the head to be tilted back, the subject to lie down or provide downward traction on the lower eyelid, or a combination of traction and tilting, since the delivery mechanism typically relies on gravity for applying the medication. This is not only awkward, but involves a fair amount of coordination, flexibility and cooperation on the part of the subject to ensure that the medication gets into the eye while avoiding poking the eye with the dropper tip. Current eye dropper bottles pose the risk of poking the user in the eye, potentially causing physical damage to the eye, and further, exposing the tip to bacterial contamination due to contact with the eye. As such, the subject runs the risk of contaminating the medication in the eye drop bottle and subsequently infecting the eye. Additionally, a large volume of the medication flows out of the eye or is washed away by the tearing reflex. As a result, this method of administration is also inaccurate and wasteful. Moreover, the technology does not provide a satisfactory way of controlling the amount of medication that is dispensed, nor does it provide a way of ensuring that the medication that is dispensed actually lands on the eye and remains on the eye.
Eye droppers also provide no way of verifying compliance by a subject. Even if after a week of use the eye dropper bottle could be checked for the total volume of medication dispensed, e.g., by weighing the bottle, this does not provide a record of day-to-day compliance. A subject may have missed one or more doses and overdosed on other occasions. Also, the poor precision with which eye droppers deliver drops to the eye leaves a question mark whether the medication actually gets into the eye, even though it may have been dispensed.
Accordingly, there is a need for a delivery device that delivers safe, suitable, and repeatable dosages to a subject for ophthalmic, topical, oral, nasal, or pulmonary use.
The present invention includes a device and method of delivering safe, suitable, and repeatable dosages to a subject for ophthalmic, topical, oral, nasal, or pulmonary use. The present invention also includes a fluid delivery system capable of delivering a defined volume of the fluid in the form of droplets having properties that afford adequate and repeatable high percentage deposition upon application.
The present invention includes and provides a device for delivering a fluid to an eye of a subject, the device comprising a housing, a reservoir disposed within the housing for receiving a volume of fluid, an ejector mechanism configured to eject a stream of droplets having an average ejected droplet diameter greater than 15 microns, the stream of droplets having low entrained airflow such that the stream of droplets deposit on the eye of the subject during use.
The invention further includes and provides a device wherein the ejector mechanism comprises an ejector plate having a first surface that couples a fluid delivery area of the reservoir, the ejector plate including a plurality of openings formed through its thickness, an actuator coupled to a second surface of the ejector plate, the actuator being operable to oscillate the ejector plate at a frequency and generate a directed stream of droplets.
Yet another implementation of the invention includes and provides a device for delivering a volume of ophthalmic fluid to an eye comprising a housing, a reservoir disposed within the housing for receiving a volume of ophthalmic fluid, an ejector plate being in fluid communication with the reservoir, the ejector plate including a plurality of openings formed through its thickness, an actuator formed on a surface of the ejector plate opposite the reservoir, the actuator being operable to oscillate the ejector plate at a frequency and generate a directed stream of droplets, wherein the droplets in the directed stream have an average ejecting diameter in the range of 5-2500 microns, including but not limited to 20-100 microns, and an average initial velocity in the range of 1-100 m/s, including but not limited to, 2-20 m/s.
Yet another implementation of the invention includes and provides for a method of delivering a volume of ophthalmic fluid to an eye of a subject, the method comprising ejecting a directed stream of droplets of an ophthalmic fluid contained in a reservoir from openings of an ejector plate, the droplets in the directed stream having an average ejecting diameter in the range of 5-2500 microns, including but not limited to 20-100 microns, and an average initial velocity in the range of 1-100 m/s, including but not limited to, 2-20 m/s.
The present disclosure generally relates to ejection devices useful, e.g., in the delivery of fluid such as ophthalmic fluid to the eye. In certain aspects, the ejection devices include an ejection assembly which generates a controllable stream of droplets of fluid. Fluid includes without limitation, suspensions or emulsions which have viscosities in a range capable of droplet formation using an ejection mechanism.
As explained in further detail herein, in accordance with certain aspects of the present disclosure, the ejector mechanism presently disclosed may form a directed stream of droplets which may be directed toward a target. The droplets will be formed in distribution of sizes, each distribution having an average droplet size. The average droplet size may be in the range of about 15 microns to over 100 microns, greater than 20 microns to about 100 microns, about 20 microns to about 80 microns, about 25 microns to about 75 microns, about 30 microns to about 60 microns, about 35 microns to about 55 microns, etc. However, the average droplet size may be as large as 2500 microns, depending on the intended application. Further, the droplets may have an average initial velocity of about 0.5 m/s to about 100 m/s, e.g., about 0.5 m/s to about 20, e.g., 0.5 to 10 m/s, about 1 m/s to about 5 m/s, about 1 m/s to about 4 m/s, about 2 m/s, etc. As used herein, the ejecting size and the initial velocity are the size and initial velocity of the droplets when the droplets leave the ejector plate. The stream of droplets directed at a target will result in deposition of a percentage of the mass of the droplets including their composition onto the desired location.
Fluids suitable for use by the ejection device can have very low viscosities, e.g., as with water at 1 cP, or less, e.g. 0.3 cP. The fluid may additionally have viscosities in ranges up to 600 cP. More particularly, the fluid may have a viscosity range of about 0.3 to 100 cP, 0.3 to 50 cP, 0.3 to 30 cP, 1 cP to 53 cP, etc. In some implementations, solutions or medications having the suitable viscosities and surface tensions can be directly used in the reservoir without modification. In other implementations, additional materials may be added to adjust the fluid parameter.
The disclosed technology includes ejected droplets without substantial evaporation, entrainment of air, or deflection off of the eye surface, which facilitates consistent dosing. Average ejecting droplet size and average initial velocity are dependent on factors including fluid viscosity, surface tension, ejector plate properties, geometry, and dimensions, as well as operating parameters of the ejector mechanism including its drive frequency. In some implementations, about 60% to about 100%, about 65% to about 100%, about 75% to about 100%, about 80% to about 100%, about 85 to about 100%, about 90% to about 100%, about 95% to about 100%, etc., of the ejected mass of droplets are deposited on the surface of the eye, such deposition being repeatable. The direction of flow of the stream of droplets may be horizontal, or any direction a user chooses to aim the actuation mechanism during use.
Without wishing to be bound by this theory, it is believed that as droplet diameter decreases, the ratio of the total surface area to total volume increases. That is, more surface area is exposed for a given total volume of fluid. Therefore, smaller droplets may create a larger surface area which creates more drag. In the low Reynolds number regime (Re<1), the drag force is given by Stoke's law, a solution to the Navier-Stokes equations. Thus, the drag force is believed to be proportional to the square root of the surface area of a droplet. Presuming that the droplet is spherical, the drag force is believed to be proportion to the diameter of the droplet.
Each particle carries air along with it (entrained air), creating an airstream. This effect of this entrained air stream is believed to be approximately proportional to diameter. When the airstream reaches a target, it may deflect or sharply turn, say by 90 degrees adjacent to the surface of the target to maintain flow. If the flow of the airstream is too large, it may carry some of the droplets with it, causing them to deflect and not deposit on the surface of the target. Particles with sufficiently large momentum will overcome this effect and successfully deposit on the surface. The stopping distance is an approximation of the distance the particle will travel before the initial momentum is diminished to zero by air friction. Entrained air created by surrounding particles will increase the stopping distance, giving each droplet a larger possible range and more opportunity for deflection. Droplets also fall vertically during their flight path due to gravity. After a short acceleration time, droplets reach their terminal velocity where the drag force is equal and opposite to the gravitational force. Larger particles fall faster because terminal velocity is proportional to their surface area. The droplet lifetime also depends on the local and ambient partial pressures, the local and ambient temperatures, and the particle diameter, all of which affect its rate of evaporation. Generally, larger particles will evaporate slower.
Again not limited by any particular theory, droplets are formed by an actuation mechanism that forms the stream of droplets from fluid contained in a reservoir coupled to the ejector mechanism. The ejector mechanism and reservoir may be disposable or reusable. They may be packaged in a housing. The housing may be disposable or reusable. The housing may be handheld, miniaturized, formed to couple to a base, and may be adapted for communication with other devices. Housings may be color-coded or configured for easy identification. Droplet ejector devices, in some implementations, may include illumination means, alignment means, temperature control means, diagnostic means, or other features. Other implementations may be part of a larger network of interconnected and interacting devices used for subject care and treatment. The ejector in one implementation may be a thermal ejector. In another, it may be an ultrasonic ejector. In yet another implementation, the ejector may be a piezoelectric ejector.
Before reaching the target, the ejected droplets may evaporate in the air. Delivering droplets having an ejecting velocity of about 1 m/s to about 5 m/s to a target located about 3 cm from the ejector mechanism may take about 0.03 s or less to reach the surface of the target. Without wishing to be bound by this theory, it is believed that the rate of evaporation is related to the diameter of the droplets and the environmental parameters including temperature and humidity. It is also believed that a long evaporation time, e.g., longer than the delivery time of about 0.03 s, is desired for effectively depositing the droplets. Assuming that the temperature is 20° C. and the fluid is water,
Referring to
Referring to
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Referring to
Referring to
In summary, the calculations in
Additionally, charging the droplets may improve their ability to reach the target. The human body, and especially the moist eye surface, is a conductor, therefore it may attract the charged droplets aiding in their contact with the target. While wishing not to be limited by this theory, the charged droplets form a space charge cloud while in transit to the target. This space charge creates an electric field E which repels the similarly charged droplets to the target by the Coulomb force. When a drop gets close to the target, the electric field from the charged droplet creates an equal and opposite image charge in the conductive target which attracts the droplet.
Several methods for charging droplets are known. Tribocharging (frictional) charging, applying a voltage to the ejector plate and charges the droplets by induction, and charging by high voltage corona discharge to generate gas ions and charge the droplets by Pauthenier field charging and/or diffusion charging are three such examples. In tribocharging the fluid is passed through small orifices, e.g., of a ejector plate or grid, which results in charging. The effect can be enhanced by coating the ejector plate or grid.
The droplet ejecting device includes ejection mechanism. In some implementations, the mechanism includes an ejection plate or substrate. In some implementations, this is coupled to a fluid reservoir, examples of which are discussed herein. One implementation of the ejector mechanism may be a thermal ejector (or “bubble jet”). The implementation of
In the implementation shown in
In one implementation the openings may be formed in the substrate have a radius of 37 microns and a substrate thickness of 74 microns with intervening streets of 12 microns for a center-to-center distance of 86 microns. Assuming spherical drops are emitted from each of the openings the volume of material in each opening will be πr2×t=π(372×74)×10−18=3.18×10−13 m3=318 pico liter. The amount of area (opening and surrounding street area) for each unit or opening is thus (37+12+37)2 μm2=7.396×10−9 m2. Thus in a substrate of 0.5 cm×0.5 cm=0.25×10−4 m2 this provides for a total of 3380 openings for a total fluid volume in the openings of approximately 1 μl.
In the above implementation a opening size of 74 microns was selected, which provides for rather large drops of fluid. It will be appreciated that the size of opening chosen will depend on the viscosity of the chemical. The duty cycle or rate of firing of the openings also depends on the volume flow that is desired and will depend on the application. In one implementation droplet sizes of the order of 300 pL may be ejected from the ejector fabricated from a substrate with ratio of opening diameter to substrate thickness of 10:1 to 1:10.
In some implementations the use of materials having a higher operating temperature and lower coefficient of thermal expansion and also provide higher thermal conductivity and lower heat capacity for rapid cooling and improved duty cycle control can be utilized. The material preferably also has a high thermal shock parameter, as is provided for example by silicon carbide (SiC) or any of its poly types (different atomic arrangements). In the present implementation the substrate may made from silicon carbide having a 6H crystal lattice configuration.
As mentioned above, while SiC always involves a combination of silicon and carbon, the crystal lattice structure may vary and includes structures such as 3C (cubic) atomic arrangements with the atoms located at the corners of cubes forming a lattice structure, or a hexagonal (4H or 6H) arrangement that repeats every four or six layers or a rhombohedral arrangement. A comparison of the arrangements and properties of 3C, 4H and 6 H are given in the table below. Such properties may provide guidance for the selection of appropriate substrate material.
As discussed above in this implementation, the substrate is coupled to a reservoir.
In order to eject fluid droplets from the openings the substrate the heating elements such as the elements 108 shown in
As mentioned above, the present invention makes use of a substrate material such as SiC, which has a high operating temperature to withstand the high heating of the fluid being ejected, a low coefficient of thermal expansion (meaning that as the temperature changes the material remain pretty constant in size), provides high thermal conductivity (thereby allowing rapid dissipation of heat between heating cycles to allow accurate control of the duty cycle), a low heat capacity, and a high thermal shock parameter. The parameters of the material allow it to rapidly heat the fluid, causing the disk of fluid in the openings that is surrounded by the heating element to heat very quickly to its boiling point, thereby explosively propelling the fluid droplet above the vapor disk from the proximal end of the opening. Other suitable substrate material such as silicon can be used.
In one implementation, an electrical circuit heats the fluid and affects the droplet ejection process. An implementation of this circuit is shown in
One benefit of the implementation is that it provides the ability to accurately control droplet ejections by controlling openings to fire and the selection of the number of openings to be fired. It also allows two or more medications to be mixed at time of ejection by providing different sets of openings with different reservoirs filled with different medications. The ratios of two or more medications can be accurately controlled by determining the number of openings to fire from each set or by adjusting the duty cycles for each set. The small droplet size of the medications emitted from the substrate material also ensures thorough mixing of the medications as they are emitted.
One implementation of the droplet ejection device is shown in
Another implementation of the invention is shown in
The device can be pointed at the target, for example, an human or animal eye, using an LED, e.g. LED 708, to help in correctly aligning the applicator. Once the eye-sensor, e.g., sensor 506, detects an eye, it sends a signal to the processor 600, which closes the second switch 612, which is implemented as a relay in this implementation, to allow current to pass from the power source to the heating elements of the thermal ejector. One implementation of the device which could be embodied in any of the implementations may include an ejector assembly and LED that turns on when the device is switched on, for example, by a power switch or lifting the device out of a docking station. The light from the LED is shone onto the target, e.g., the subject's eye to correctly target the eye prior to dispensing fluid. The device may include a rest, support, or spacer to aid in alignment as discussed below.
Other implementations to ensure correct alignment of the device with the eye are also contemplated. These implementations, examples of which are shown in
Yet another implementation of the invention is shown in
In
Implementations of the device provides numerous benefits over other devices for many reasons. For example, not only does it ensure that the fluid that is dispensed is dispensed into the eye by allowing the device to be correctly aligned, the device is capable of dispensing at speeds that ensure beating the blink of an eye. Using a thermal ejector based system in accordance with the invention and integrating it with an optical camera or other eye detector or eye sensor, to provide feedback to the device ensures that the eyelid is open and that the eye is correctly aligned with the thermal ejector. Only when the eye is determined to be open will the applicator of the invention dispense a carefully measured dose of medication or vaccine in the form of a fine mist directly into the eye. The sub-second response time, is particularly useful for people or animals who are sensitive to anything coming close to their eye by ensuring that the speed of delivery is able to “beat the blink”. Other benefits of the device include delivering quantifiable and repeatable results by selectively dispensing a precisely controllable volume of fluid such as a medication or vaccine.
Different implementations as understood and disclosed permit a user to turn on the device. A user may simply lift the device off of a base which then activates or turns on the device. The user can also turn on the device by depressing a trigger, such as trigger 504. In some implementations, where the ejector mechanism is thermal or ultrasonic, engaging the trigger or turning on the device, commences to heat or cool the device or portions thereof to a predetermined temperature. For example, the device may be heated or cooled to the body temperature of a human or animal.
After the device is turned on, the ejection mechanism can be triggered. In the implementation of
Some implementations may include a watchdog timer which monitors the device to ensure proper operation. In another implementation, the device may sense the presence of the droplet steam for self-diagnostic purposes and to confirm proper operation. By way of example, one or more light emitters, e.g., LED, laser diode, may be used to shine light against the droplet stream. In one implementation, the light may be shown perpendicularly to the stream. A device may include, in one implementation, light detectors, e.g., photo detector, which may be used in conjunction with a shone light to detect reflection and refraction, such as reflection of the shone light off of the stream, and use this detection to determine proper operation of the device. A system may further react in response to the detection and determination of proper operation, e.g., by alerting a compliance agent or system that the device may not be properly functioning.
In the implementation of
The illumination mechanism, such as the LED explained above, may be in ranges above 280 nm, including, e.g., 290-1600 nm, wavelengths for illuminating the target. The illumination mechanism may be operable to pulse the light for different periods of time, e.g., 120 ns to limit pupil reaction and permit analysis of the eye with different frequency optical detectors, scanners, or cameras as explained above. Furthermore, the device may include an adaptive optics chip to perform wavefront correction for clearer images. The device may also include a fixation source e.g., an LED or LED pattern to define a moving eye-focusing image and assist with pediatric usage. This also serves to move or rotate the eyeball during application of medication to assist in spreading the medication across the corneal surface.
Features of the devices can be formed in alternative implementation. The following are a few examples.
The cover may also hinge up as shown in
In some instances, it may be desirable to control the temperature of the fluid in the device outside of the ejection cycle. In these implementations, the device may include a cooler, e.g., a Peltier device, for keeping the fluid cool where needed. The device may also include a heater for warming the fluid to a predefined temperature, e.g., the eye surface temperature of the person to whom the fluid is to be administered. The temperature range may be controlled by the controller.
In addition to the thermal and ultrasonic ejector mechanism, the ejector mechanism may be piezoelectric. Referring to
Referring to
Additionally, the openings 1626 may be formed in any suitable shape or volume with an appropriate aspect ratio. One example is shown in
Ejector plate 1602 is coupled to an ejector which activates the plate to form the droplets upon activation. The manner and location of attachment of the ejector 1604 to the plate 1602 affects the operation of the ejection assembly and the creation of the droplet stream. In the implementation of
As with the size and shape of the openings 1626, the size and shape of the ejection region 1632 can be selected based on the desired properties of the droplet stream. As shown in
Other than the open region 1638, portions of the ejector plate 1602 may be covered by an additional reservoir wall 1650. In the implementation of
As the ejection assembly 1600 is used for delivering therapeutic agents or other fluids to eyes, the ejection assembly 1600 is designed to prevent the fluid 1610 contained in the reservoir 1620 and the ejected droplets 1612 from being contaminated. In some implementations, for example, as shown in
Referring to
Additionally, surface 1622 of plate 1602, e.g.
In some implementations, the ejector plate 1602 can itself be formed of a metal, e.g., stainless steel, nickel, cobalt, titanium, iridium, platinum, or palladium or alloys thereof. Alternatively, the plate can be formed of suitable material, including other metals or polymers, and be coated as noted above. The plate may be a composite of one of more materials or layers. The plate may be fabricated for example by cutting from sheet metal, pre-forming, rolling, casting or otherwise shaping. The openings in the plate may be formed using suitable methods including but not limited to drilling by mechanical or optical means such as laser drilling or ablation, or chemical processing such as etching with or without stencils or lithographic patterning. The openings may also be pre-formed at the time of forming the plate. The coatings may be pre-formed by dipping, plating, including electroplating, or otherwise encapsulating such as by molding or casting. The coatings may also be deposited by suitable deposition techniques such as sputtering, vapor deposition including physical vapor deposition (PAD), chemical vapor deposition (COD), or electrostatic powder deposition. The protective coating may have a thickness of about less than 0.1 μm to about 500 μm. It is desirable that the coating adhere to the plate 102 sufficiently to prevent delamination when vibrating at a high frequency.
The configuration of the reservoir 1620, including the shape and dimension, can be selected based on the amount of fluid 1610 to be stored and the geometry of the ejector plate 1602. Alternative forms of reservoirs include gravity-fed, wicking, or collapsible bladders which operate under pressure differentials. These reservoirs may be prefilled, filled using a micro-pump or by replacement of a cartridge. The micro pump may fill the reservoir by pumping fluid into or out of a collapsible container or a noncollapsible one. The cartridge may include A container which is loaded into the reservoir. Alternatively, the cartridge itself may be coupled to a disposable ejector assembly which is then replaced within the housing after a specified number of discharges.
In the example shown in
In some implementations, the reservoir housing 1608 includes through holes 1642 (only one shown in
In the implementation of
Many piezoelectric materials can be used to create actuator 1604. By way of example, in some implementations, the piezoelectric actuator can be formed from PZT. But PZT includes lead and should be sealed from fluid 1610. Other lead-free materials include barium titanate or polymer-based piezoelectric materials, such as polyvinylidene fluoride. The electrodes 1606a and 1606b can be formed of suitable conductors including gold, platinum, or silver. Suitable materials for use as the adhesive 1628 can include, but not be limited to, adhesives such as silicone adhesives, epoxies, silver paste. One example of a conductive adhesive includes Thixotropic adhesive such as Dow Corning DA6524 and DA6533. The reservoir housing 1608 can be formed of a polymer material, a few examples of which include Teflon®, rubber, polypropylene, polyethylene, or silicone. As mentioned earlier, all or part of the reservoir can be flexible or collapsible. The size and velocity of the droplets ejected by the ejection assembly 1600 can be affected by various parameters used in fabricating the ejection assembly 1600. The parameters can include dimensions of the piezoelectric actuator 1604, the properties (e.g., dimensions, elasticity and others) of the ejector plate 1602, the size and pattern of the openings 1626 in the ejector plate 1602, the frequency, shape, and magnitude of the pulses applied to the electrodes 1606a, 1606b by the drive electronics, the fluid properties (e.g., the viscosity and surface tension), and others.
The magnitude and frequency of the ejector plate vibration can also be controlled by controlling the voltage pulses applied to the electrodes 1606a, 1606b. As discussed above, the pulses are created by voltage differentials that deflect plate 1602, as shown in
In the implementation of
Additionally, and not intending to be bound to this theory, pulsing might reduce the peak amplitude of the airstream by spreading the impulse out over time, similar to the effect of an automobile crumple zone during a crash. Therefore, the pressure of the ejection on the target may be mitigated. That is, e.g., for an ocular application, the subject might not feel as much air and experience higher discomfort levels. Furthermore, pulsing may also reduce droplet agglomeration and result in less entrained air generation. By way of a single example, pulses of 25 ms can be administered with stop times of 25 ms separating the pulses. By way of example, in one implementation, the pulses may be repeated for a total of 150 ms total time.
Thus, the combination of the position of the thumb rest and the placement of the back of the thumb on the cheek bone provide a natural and repeatable alignment feature and process. Depending on the user's anatomy, a different portion of the thumb or hand may be aligned with an alternate location on the face to affect proper alignment. Alternatively, the device can be held a suitable distance during use, for example, as noted with respect to distance d shown in
During use, the device is held, turned on, aligned, and the delivery button depressed. Turning on the device may manually occur by activation of a physical activation trigger or may occur automatically or in response to a condition, e.g. removal of the device from a docking station. The device may cycle through a cleaning cycle once activated. The properly aligned housing delivers the fluid in the form of the droplet stream to the target.
The housing 2206 may be made from, for example, injection molded plastic or any other suitable, durable, or lightweight material. The housing 2206 may include an opening 2228, a positionable slider 2230, an interface 2232 that sends communications to and receives communicates from the docking station 2250, a stream activator 2234, and a communications interface 2236. The communications interface 2236 sends data to and receives data from a source external to the housing 2206 (see U.S .application Ser. No. 13/184,468, entitled “Method and System for Performing Remote Treatment and Monitoring,” filed concurrently herewith, and herein incorporated by reference in its entirety) to the device 2202, and the docking station 2250. For example, the communications interface 2236 may be in communication with the database or with an input/output device, such as a keyboard.
The opening 2228 may be in the form of an aperture formed through an exterior surface of the housing 2206, and the opening 2228 allows fluid stored in the reservoir 2212 to exit the housing 2206. The opening 2228 may be similar to those explained earlier.
The positionable slider 2230, which may be similar to the thumb slider described earlier. The housing 2206 also includes an interface 2232 configured to receive the connection 2204. The connection 2204 may be, for example, a one-wire, two-wire, or 12C interface. The interface 2232 allows the device 2202 to send data to and receive data from the docking station 2250 over the connection 2204.
The housing 2206 also includes an activation trigger 2234. The trigger may be, for example, a button that protrudes from the exterior surface of the housing 706, a switch, or any other tactile interface that is accessible to a user of the device, such as the switches described above. The trigger 2234 may be on a side of the housing 2206 that is opposite from the side of the housing 2206 that includes the opening 2228 and the slider 2230.
The housing 2206 also may include a communications interface 2236 that is in communication with the electronic storage 2216 and allows retrieval of data stored in the electronic storage 2216 and writing of data to the electronic storage 2216. The interface 2236 may be, for example, a universal serial bus (USB) connection, a serial connection, an Ethernet connection, or any other connection that allows reading and writing of data. Further discussion of these aspects appears in U.S. application Ser. No. 13/184,468, entitled “Method and System for Performing Remote Treatment and Monitoring,” filed concurrently herewith.
The device 2202 includes the electronics 2208, which provide one or more output driver signals to the ejector mechanism actuator or piezo 2210. The piezo 2210 vibrates, moves, or distorts the ejector plate 2202 in response to application of the output signals. The ejector plate 2202 is in contact with fluid stored in the reservoir 2212, and, when the piezo 2210 distorts, fluid from the reservoir 2212 is pulled through one or more openings formed in the ejector plate. In the piezoelectric implementation, the motion of the ejection plate, and in general, the operation of the ejection mechanism, causes a directed stream of droplets to exit the housing 2206 through the opening 2228.
As discussed in greater detail with regard to figures disclosing electronics, the electronics 2208 determine the frequency, voltage, duty cycle, and duration of the output driver signal 2342 that is applied to the piezo 2210. Additionally, the electronics 2208 are programmable such that the characteristics or properties of the output driver signals applied to the piezo 2210 may be adjusted to accommodate changes in the fluid and/or a dosage plan.
The reservoir 2212 may be pre-filled with fluid when the device 2202 is manufactured. The device 2202 may be programmed at the time of manufacture of the device 2202. Alternative reservoirs as discussed can be used without limitation.
The device 2202 also includes the targeting device 2214. The targeting device 2214 may assist the user to align the device 2202 with an eye of the subject. The targeting device 2214 may be, for example, an LED that shines in the subject's eye, a reflective or shiny surface that reflects the subject's eye, and/or a CCD camera that images the subject's eye and provides a signal to the electroVINNOnics 2208. The targeting device 2204 may include a reflector to provide the user with an image of his or her eye when the device 2202 is correctly positioned, or may include a light source, such as a low intensity LED, for shining into the user's eye when the device 2202 is correctly positioned. The targeting device 2214 may include a sensor that determines whether or not the subject's eye is open. The targeting device 2214 may include an element that shows a reflection of the subject's eye when the device 2202 is properly aligned with the eye. For example, the ejector plate and/or piezo 2210 may be made from a reflective material that shows a reflection of the subject's eye when the opening 2228 and the piezo 2210 are aligned with the subject's eye. This type of targeting device is helpful for instances where the subject is using the device 2202 to administer a directed stream of droplets to their own eye.
In alternative implementations, all or part of the surface of the ejector mechanism or the housing adjacent thereof may be coated with a reflective layer. A coating layer may be both protective and reflective. Alternatively, the surface may have been formed to be reflective. For example, the surface may be made of stainless, nickel-cobalt, or other reflective material. A surface may have been formed or polished to be reflective. In addition to making the surface reflective, the surface may also be backlit on its surface or around its perimeter. In ophthalmic applications, a reflective surface aids the user in aligning the ejector assembly with the eye.
The device 2202 also includes the electronic storage 2216 and the I/O interface 2218. In addition to storing data such as images of the subject's eye, the electronic storage 2216 stores instructions, perhaps as a computer program, that, when executed, cause a processor included in the electronics 2208 to communicate with other components in the device 2202. The processor may be, for example, a state machine such as an FPGA or an ASIC. The excitation signal 2340 may be generated by a signal generator. Information on the electronic storage 2216 may be accessed through the interface 2218 or the interface 2236 (which communicates with a database), and access to the contents of the electronic storage is controlled, e.g., password restricted to allow certain activities to be conducted by certain medical personnel, e.g., doctors or pharmacists wishing to adjust dosages. Insofar as the computer is Internet enabled, information may be uploaded to via the Internet, e.g. to a server for access by medical personnel to allow progress and proper subject use to be monitored and allow dosages to be adjusted over the Internet, e.g., by uploading revised dosage information to a server by the medical personnel and then pushed to the device via the Internet or downloaded by the user. The device itself may be Internet enabled to allow usage information and image information to be uploaded in real time and new information to be downloaded to the device in real time. Insofar as the device is Internet enabled it may be provided with a user interface, e.g. screen and keyboard or touch sensitive screen.
The input/output interface 2218 provides an interface that allows data and/or commands to be input to the device 2202 and/or read from the device 2202. The input/output interface 2218 may receive data from a device such as a keyboard, a mouse, a communications port, an electronic processor executing on a device separate from the device 2202, or a display. The input/output interface 2218 also may include software that allows communication between the device 2202, the components of the device 2202, and/or an external device. The interface 2218 may provide the user with access to the device 2202 when the device 2202 is plugged into a computer, such as a laptop or palmtop or cellular phone with screen and user input capabilities, through the interface 2218.
The device 2202 also may include an imaging device 2220. The imaging device 2220 may be a charged coupled device (CCD) that is aligned with the opening 2228 such that the imaging device captures an image of the subject's eye through the same aperture that delivers the directed stream of droplets of fluid. In some implementations, the imaging device 2220 is mounted on an external surface of the housing 706 in a location other than the location of the opening 2228. Images collected by the imaging device 2220 may be transferred from the device 2202 through the I/O interface 2218, the communications interface 2236 or 2256, and/or the images may be stored in the electronic storage 2216. The images may be uploaded to the database and stored in association with the subject's medical records, as more fully explained in U.S. application Ser. No. 13/184,468, entitled “Method and System for Performing Remote Treatment and Monitoring,” filed concurrently herewith and herein incorporated by reference in its entirety.
The imaging device 2220 and the electronics 2208 may be operable to control the capture of images during or at selectable times before or after ejection of fluid from the device 2202. In some implementations, the capture of images may be triggered by the user by, for example, depressing a button or the stream activator 2234. For example, saline droplets may be directed from the device 2202 towards the eye to exert a pressure on the cornea and images may be taken to determine the effect. The images may be saved as discussed above.
The device 2202 also may include the look-up table 2222. The look-up table 2222 may be stored on the device 2202, for example, in the electronic storage 2216, or the look-up table may be stored separately from the device 2202, for example, in the database. The look-up table 2222 includes information specific to fluids that may be used in the device 2202. For example, because viscosities of fluid drugs vary, depending on the fluid in the reservoir, the piezo 2210 may require application of output driver signals having a frequency tailored to the fluid in the reservoir. This medication-specific variation may be accounted for by varying the properties, such as the frequency, voltage, and/or duration of the output driver signals produced by the electronics 2208 and applied to the piezo 2210. The look-up table 2222 may include information specific to the medication that is retrieved and used by the electronics 2208 to set the output driver signals.
The look-up table 2222 also may include medication-specific information that relates to the subject's treatment plan. For example, the look-up table may include information specifying that a first medication is to be applied three times a day, while a second medication is to be applied once a day. This treatment plan information is used by the electronics 2208 to determine, for example, when to trigger a reminder alert for the subject based on the type of medication that is placed in the reservoir.
In some implementations, the look-up table 2222 on a specific device 2202 may be edited by a professional, e.g., medical professional to account for changes in the subject's condition. The interface 2236 may be operable to download information, for example, via an external I/O device or directly from the database, perhaps via the Internet. The downloaded information may include one or more of revised dose amounts, revised dose times, and medication type to be dispensed. The device 2202 may be configured such that the electronics 2208 controls the dispensing of medication in response to pre-defined information or the downloaded information.
The device 2202 also may include a speaker 2224 and an illuminator 2226, both of which may be used, in conjunction with the electronics 2208, to provide a perceivable alert to the user of the device 2202. The device 702 may provide other perceivable alerts. For example, the device 2202 may vibrate to attract the user's attention. The device 2202 may produce an audible alarm or enunciator, or visual indicator controllable by the electronics 2208 to provide feedback to the user, for example, visual or audible feedback to indicate when a full dose has been reached. The illuminator 2226 may be an LED or other device that emits visible radiation in response to electrical input.
In some implementations, the illuminator 2226 may include multiple light sources of different frequencies for illuminating the eye, or may include a variable frequency light source, such as light of different colors and frequencies (e.g., red, blue, green, white, infrared (IR), ultraviolet (UV)). The device may include a cobalt blue light (generated, for example, by using a filter) for use with fluorescein to illuminate the cornea for identifying corneal ulcers and scratches. The illuminator 726 may be a radiation source that emits frequencies above 280 nm wavelengths for illuminating the eye. The illuminator 2226 may be operable to pulse the light for different periods of time, for example, 20 nanoseconds (ns) to limit pupil reaction and permit analysis of the eye with different frequency optical detectors, scanners or cameras. The illuminator 2226 may include an adaptive optics chip to perform wavefront correction for clearer images, for example, a MEMS based adaptive optics chip.
The device may also include a fixation source e.g., an LED or LED pattern to define a moving eye-focusing image and assist with pediatric usage. This also serves to move or rotate the eyeball during application of medication to assist in spreading the medication across the corneal surface.
The docking station 2250 includes a housing port 2252 (including without limitation, a docking station) that is configured to receive the device 2202. The housing port 2252 may be recessed such that, when the device 2202 is received by the docking station 2250, the device 2202 is seated securely and is stably held by the docking station 2250. The docking station 2250 also may include a communications interface 2256 that reads and writes data from the docking station 2250 and/or the device 2202. The communications interface 2256 may be, for example, a USB connection, an Ethernet connection, or a serial connection. The docking station 2250 also may include a memory or an electronic storage 2254.
The electronic storage components 2216 and 2254 may be volatile memory, such as RAM. In some implementations, and the electronic storage components 2216 and 2254 may include both non-volatile and volatile portions or components.
Referring to
The driver circuit 2306 is controlled by, and receives the excitation signal 2340 at a particular frequency from, the processor 2304. Controlling the driver circuit 2306 with the processor may provide a system that has increased flexibility and applicability as compared to a system that relies on a driver circuit alone. For example, controlling the driver circuit with the processor allows the frequency of the output driver signals 2342 produced by the driver circuit to be determined and changed quickly by modifying the properties of the drive signal 2340 produced by the processor. This may allow the device 2202 to adapt to changing subject needs and to operate with the various fluids that may be placed in the reservoir 2302. Additionally, controlling the driver circuit 2306 with the processor 2304 may eliminate the need for a separate potentiometer to control the frequency of the excitation signal 2340. Use of the processor 2304 to control the driver circuit 2306 may allow the electronics 2208 to be reduced in size such that the device 2202 may be held and operated by a single human hand.
The processor 2304 receives data and control signals from a push switch 2308, a programming interface 2310, and a slide switch 2312. The processor may be connected to the driver circuit through an electrically conductive path 2314, such as a copper trace. The push switch 2308, the programming interface 2310, and the slide switch 2312 may be electrically connected to the processor through traces 2314, 2316, and 2318, respectively.
The push switch 2308 is coupled to the activation trigger 2234, the mechanism by which a user of the device 2202 causes release of the directed stream of droplets. The push switch 2308 and a portion of the stream activator 2234 may physically contact each other when the user of the device 2202 presses or otherwise selects the stream activator 2234. In implementations in which the stream activator 2234 is electronic (for example a softkey), the stream activator 2234 may not necessarily be in physical contact with the push switch 2308, rather the stream activator 2234 may provide an electronic indication of selection to the push switch 2308. In response to receiving an indication of activation from the activator trigger 2234, the push switch 2308 generates a spray signal to the processor 2304.
The programming interface 2310 allows the processor 2304 to be programmed to, for example, produce a excitation signal 2340 that has a particular frequency, duration, or time between active states. For example, the processor 2304 may be programmed to generate a excitation signal 2340 having a frequency between about 108 kiloHertz (kHz) and 183 kHz. The programming interface 2310 may be, for example, a 5-pin interface. In some implementations, the programming interface 2310 may be accessible through a graphical user interface (not shown).
The processor 2304 provides the excitation signal 2340 to the driver circuit 2306, and the driver circuit uses the excitation signal 2340 to produce two output driver signals that are applied to the piezo 2320. Each output driver signal 2342 may be a square wave, or approximately a square wave, and each output driver signal 2342 may have approximately the same maximum and minimum voltage. The maximum voltage of the output driver signals may be approximately 20 to 40 volts, and the minimum voltage may be approximately zero (0) volts. The second output driver signal 2342 may be out-of-phase with the first output driver signal, and the first and second output driver signals may be out of phase by approximately 180 degrees.
The slide switch 2312 is coupled to the slider 2330. For example, in implementations in which the slider 2230 is a physical slider, the slide switch 2312 may be physically connected to the slider 2230 such that the slide switch 2312 generates a signal when the slider 2230 is positioned in one or more pre-defined positions on the housing 2206. In some implementations, the slider 2230 may be electronic and may communicate with the slider switch 2312 electronically instead of mechanically. The slider 2330 also may be provided with a metalized surface operable, when the slider 2330 is moved into the open position, to bridge the gap between two metal contacts, thereby defining a slide switch. The slide switch 2312 may generate a signal when the slider 2230 is moved to a position that reveals (or uncovers) the opening 2228. This signal may be referred to as an initiation signal. The slide switch 2312 may generate another signal when the slider 2230 is moved from that position. Signals generated by the slide switch 812 are provided to the processor 2304.
Referring to
The piezo 2320 holds and/or is in contact with the ejector plate 1602 (
In one implementation, the piezo 2320 is mounted on the printed circuit board (PCB) 2301 and contacts a conductive surface (not shown) on the PCB board 2301. The conductive surface may be stainless steel. In some implementations, the conductive path 830 is a discrete wiring, not integrated with the board 2301, that connects the piezo 2320 to an output of the driver circuit 2306. In some implementations, the conductive path 2330 is a trace made directly on the PCB board 2301. In these implementations, a conductive material is placed between the piezo 820 and the o-ring and reservoir 2302. The conductive material may be, for example an elastomer or “Zebra strip.” In these implementations, the discrete wire is eliminated and the output driver signal 2342 from the driver circuit 2306 is provided to the piezo 2320 by a conductive trace formed directly on the PCB board 2301. The piezo 2320 may be aligned with the opening 2228 to allow the directed stream of droplets to exit the device 2202.
In some implementations, the configuration 800 includes a second piezo that is coupled to the reservoir that is mounted on the top of the PCB board. In this implementation, the driver circuit 2306 is configured to generate four output driver signals 2342 to drive the two separate piezos. The second piezo may be mounted directly to the surface of the reservoir 2302 such that the reservoir 2302 vibrates with the second piezo. This vibration may help to ensure that the fluid in the reservoir 2302 remains in a fluid state and to help prevent the formation of crystals and other solid particles in the reservoir 2302. In the case of medications provided as a suspension, the vibration may be operable to churn up the medication.
The LED 2322 receives power from the power module 2326 and a signal to turn ON or OFF from the processor 2304. The processor 2304 also provides a signal to the speaker 2324 to turn ON or OFF. The configuration 2300 includes a remote control module 2328 that allows for remote configuration and/or control of the processor 2304. The power module 2326 may be one or more batteries. For example, the power module 2326 may include three batteries.
Whether an opening in the housing is substantially free from obstruction is determined 2404. The directed stream of droplets is released from the device 2202 when the slider 2230 is in a position that reveals, rather than covers, the opening 2228. When the slider 2230 is positioned in a position on the housing that reveals the opening 2228, the slide switch 2312 generates a signal that is provided to the processor 2304. If this signal has not been generated, the opening 2228 is not substantially free from obstruction. If the signal has been generated, the opening 2228 is substantially free from obstruction such that a directed stream of droplets may be released from the device 2202.
An excitation signal is generated in response to receiving the indication of activation and determining that the opening in the housing is substantially free from obstruction 2406. The excitation signal 2340 is applied to the driver circuit 2306, which in turn generates two voltage signals (output driver signals) that are applied to the piezo 2320 (or piezo 2210) to cause the piezo and the ejector plate 1602 attached to the piezo to vibrate, move, or otherwise distort. The motion of the ejector plate 1602 draws fluid from the reservoir 2302 and through one or more holes in the ejector plate, creates a directed stream of droplets of fluid for delivery to the subject's eye. The excitation signal 2340 may be a square wave having a frequency of about 95 kHz to 183 kHz. The excitation signal 2340 is applied to the driver circuit 2306, and the driver circuit 2306 produces two square wave output driver signals that are 180° out of phase with each other and that are applied to the piezo 2320. The voltages of the square wave output driver signal 2342 may be, for example, 20 to 40 volts, and the frequency of each output driver signal 2342 may be between about 95 kHz to 183 kHz.
An indication that a thumb slide has moved into a second position is received (2502). The thumb slide may be a slider similar to the slider 2230, and the second position may be a location on the surface of the housing 2206 that reveals the opening 2228 such that the directed stream of droplets may exit the device 2202. The indication of that the slider 2230 has moved may be a signal generated by the slide switch 2312 in response to the slider making mechanical or electrical contact with the slide switch 2312. A excitation signal 2340 is generated in response to receiving the indication (2504). The excitation signal 2340 may be generated by the processor 2304, and the excitation signal 2340 may be a signal that controls the driver circuit 2306 to produce output driver signals that drive the piezo to perform a preparation sequence. The preparation sequence may be referred to as an initiation sequence, a purge cycle, or a cleaning cycle.
The preparation sequence causes the device 2202 to produce one or more directed streams of droplets that are not intended for placement in the subject's eye. Rather, the one or more streams produced in the preparation sequence flush out the barrier, the hole in the barrier, the reservoir, and other internal components of the device 2202. The preparation cycle may reduce or eliminate contaminants and residues that may accumulate in the device 2202 between uses. In some implementations, about 8 to 10 directed streams of droplets are produced during the preparation sequence. Although the directed stream of droplets released during the preparation sequence is not intended for placement in the subject's eye, the medication in the reservoir is used as the fluid during the preparation cycle to clean and/or prepare the device for use.
In some implementations, the drive signal 2340 applied to the driver circuit 2306 causes the driver circuit to produce two output driver signals with a waveform having a cycle that lasts for a total of about 50 milliseconds, and for about 30 milliseconds of the cycle while the output driver signal 2342 is ON, and for about 20 milliseconds while the output driver signal 2342 is OFF (that is, essentially no output driver signal 2342 is applied to the piezo). The preparation cycle may include applying these output waveforms to the piezo for about 8 to 10 cycles of the waveform. When the output waveform is ON, the piezo vibrates and draws fluid from the reservoir through the barrier to clean the components of the device 2202.
An indication that the preparation sequence is complete is received 2506, and a perceivable alert is presented upon completion of the preparation sequence 2508. The perceivable alert may be, for example, the LED 2322 turning ON. The alert lets the user of the device 2202 know that the device 2202 is ready for use. If an indication of an activation of a tactile interface is not received within a predetermined amount of time after the completion of the preparation sequence, a sleep mode is initiated 2512. If an indication of an activation is received within the predetermined amount of time, it is determined whether the opening in the housing is substantially free from obstruction such that a directed stream of droplets may exit the housing 2206.
If an indication that the thumb slide has moved into a first position is received, then the sleep mode is initiated 2512. The first position may be a position in which the thumb slide covers the opening in the housing. If an indication that the thumb slide has moved into the first position has not been received, the device 2202 remains ready to receive an input from the user until a predetermined amount of time has elapsed. After the predetermined amount of time has elapsed, the sleep mode is initiated.
The processor 2304 may be programmed to dispense only a predetermined number of dosages, such as 30 dosages, 60 dosages, or 180 dosages, and additional activation of the tactile interface does not produce a directed stream of droplets.
Other alternative implementations are also contemplated. By way of example, in one implementation, ejection plates are created by precise micro fabrication techniques. A size of microspheres ejected from such a plate will vary in volume according to the magnitude of plate motion. The frequency of the plate motion is influenced by the frequency of an electrical voltage (typically a square wave) that drives the piezoelectric actuator attached to the ejector plate. Typically the actuating frequency will be in the range of 50 kHz to 200 kHz and will have a duration great than about 0.1 milliseconds.
Drug volume per dose is calculated from the diameter of the ejected spheres, number of holes in the plate, frequency of vibration, number of voltage cycles per ejection per hole, and length of time the plate is vibrated. For example an ejection plate having 1000 holes that are 20 microns in diameter may eject spheres about 40 microns in diameter. If a sphere ejects from each hole about once per ten cycles then a 100 kHz vibration from the piezoelectric element will eject about 100,000/10 spheres per hole per second or about 10,000,000 spheres per second when all 1000 holes are ejecting fluid. If each sphere is 40 microns in diameter then the ejector plate will dispense about 10,000,000*4/3*pi*((40e-6)/2)^3 cubic meters per second or about 10,000,000*4/3*pi*((40e-3)/2)^3=335 microliters per second. If the plate is actuated for 20 milliseconds then about 6.5 microliters of drug are ejected.
Without being limited by theory, sphere size and velocity are related to the amplitude and frequency of the waveform voltage driving the piezoelectric element. In part, this is because magnitude of the ejector plate motion and piezoelectric motion is related to frequency of the driving signal. Magnitude of the piezoelectric motion is related to the voltage of the applied voltage. Ejection velocity is also dependent on the frequency and magnitude of the applied voltage. In some implementations, spheres are not effectively ejected except near resonant frequencies or their harmonics. In an implementation, spheres ejected at these frequencies will be optimized for maximum speed and volume. Unfortunately, variation in manufacture of piezoelectric elements can cause resonant frequencies to vary about 10% from the average. This variation results in each dispense unit needing a slightly different voltage or frequency to achieve the same dispense velocity and volume. Each unit can be tuned during manufacture for a specific frequency. The oscillation of the piezoelectric element is highly dependent on frequency. Therefore, optimization of frequency is a often needed and control of the frequency of a square wave can be accomplished by changing the frequency of the internal square wave generator (typically a microprocessor or FPGA).
In certain implementations of a portable device, voltage and power applied to the piezoelectric element can be limited by breakdown voltages of electrical components and total battery energy. Voltage can be minimized to reduce power consumption while still achieving optimal ejection of spheres. Tuning the frequency slightly off the resonant frequency allows control of the ejection velocity and plume shape for a given applied voltage. Similarly total mass ejected per dose is controlled by the duration of ejection. Thus a final tuning of driving frequency and pulse time is needed to set ejection velocity and dose volume.
One implementation described here is a device and method for tuning the ejection velocity and dose size for a portable ophthalmic dispenser. In an implementation of this a small target plate with an associated weighing mechanism and a vision system that observes the region between the dispenser and target plate. A test fixture controller dispenses the dose for a fixed time and receives the weight and velocity of the dispensed dose. A controller calculates appropriate modifications in the ophthalmic delivery device. A ophthalmic dispenser has a programmable internal controller with static memory (such as EEPROM) to store optimized parameters.
A vision system will measure the velocity of the dispense. Typical dispense velocities are in the range of 0.5 to 10 meters per second with typical time of flight of 4 to 80 milliseconds travelling a distance of 4 cm. Thus a camera with a frame rate faster than 100 frames per second and ideally 10,000 frames per second would measure the leading edge of a dispense as it travels from the dispenser to the weighing station. Accuracy of measuring the front edge of the droplets depends upon an effective illumination source, effective optics, and the camera's resolution.
In one implementation operation, a dispenser will be placed in the tuning station in a rigid jig (or brought to the test area in a jig) with electrical connections to the dispenser. A dose will be dispensed towards the target about 4 cm away as the vision system measures the velocity of the front edge of the ejected droplets. Then the target will be weighed. A controller then calculates the dispense volume and velocity. Typically dispenses will be done at multiple frequencies to determine the optimal dispense frequency for correct droplet velocity. Dosage per dispense will be measured by the weighing system at this frequency and then dispense time will be set to a value that gives the correct dosage.
At appropriate times the dispense fluid is cleaned from the target with a blast of air followed by another weighing to tare the system. For accurate dose measurement multiple dispenses may be done to increase the total mass measured. Then, an average can be taken to determine the mass of a single dose.
Additionally, a vision system can be used to verify the width of the dispense plume and even infer droplet size according to the degree to which the droplets are carried around the target by the airflow. This data can be collected in one or two directions (for example, from above or from the side) to verify aim of the dispenser plate if needed. Similarly, a vision system that observes droplet flight from the side can infer dispense velocity and droplet size from the amount that the dispense falls below the target. With higher dispense velocities the vertical position of the droplets will change less.
In order for this system to work, each portable device may have an externally programmable memory to hold the calibration constants or formula for piezoelectric frequency and pulse duration. For consumer and particularly prescription applications, each unit can, if desired for that implementation, store the number of doses it is allowed to dispense. Knowing the volume of the fluid is allows for overfilling, which can optionally use for calibration sprays and cleaning sprays which may occur each time the unit is opened. In one implementation a entire ejector plate wetted for a full-dose dispense. A full wetting requirement may result in excess drug that can be stored in the dispenser so that at the end of user dosing there will be drug left in the dispenser.
In one implementation, number of doses ejected can be restricted both for the consumer to prevent partial doses being used and for the supplier of the device so that per dose is accurately accomplished. For example, if a unit was 20% overfilled then the consumer might buy 20% fewer units on an annual basis in the case of long-term use of the device.
In one implementation, along with calibration constants and dose limits, the memory may be programmable to allow the same unit to dispense different sized doses in the case where a smaller person or child should receive smaller doses of the drug. Similarly, in cases where the unit should alert the user if a dose is overdue, as in the case of a glaucoma medication where regular application of the drug is key to minimizing damage by the disease, medication intervals and even an internal clock might be set. For example, during the day doses might be required every four hours but no doses are required from 9 pm to 6 am when the person is sleeping. In one implementation, a point of calibration of the dispense system or later during packaging or prescription sales the user constants might be downloaded to the device.
Many implementations of the invention have been disclosed. This disclosure contemplates combining any of the features of one implementation with the features of one or more of the other implementations. For example, any of the ejector mechanisms, or reservoirs can be used in combination with any of the disclosed housings or housing features, e.g., covers, supports, rests, lights, seals and gaskets, fill mechanisms, or alignment mechanisms. Further variations on any of the elements of any of the inventions within the scope of ordinary skill is contemplated by this disclosure. Such variations include selection of materials, coatings, or methods of manufacturing. Any of the electrical and electronic technology can be used with any of the implementations without limitation. Furthermore, any networking, remote access, subject monitoring, e-health, data storage, data mining, or internet functionality is applicable to any and all of the implementations and can be practiced therewith. Further still, additional diagnostic functions, such as performance of tests or measurements of physiological parameter may be incorporated into the functionality of any of the implementations. Performance of a glaucoma or other ocular tests can be performed by the devices as a part of their diagnostic functionality. Other methods of fabrication known in the art and not explicitly listed here can be used to fabricate, test, repair, or maintain the device. Furthermore, the device may include more sophisticated imaging or alignment mechanisms. For example, the device or base may be equipped with or coupled to an iris or retina scanner to create a unique id to match a device to the user, and to delineate between eyes. Alternatively, the device or base may be coupled to or include sophisticated imaging devices for any suitable type of photography or radiology.
To assist in understanding the present invention, the following Example is included. The experiments described herein should not, of course, be construed as specifically limiting the invention and such variations of the invention, now known or later developed, which would be within the purview of one skilled in the art are considered to fall within the scope of the invention as described herein and hereinafter claimed.
An implementation of the disclosure may be carried out through this Example. Although many arrangements are possible, one implementation uses an annular PZT piezo attached directly to a circular 80 microns thick Ni—Co ejector plate, having a diameter of 0.5 cm. The ejector plate contains eighty-nine 30 microns cylindrical holes bored through the center with a 380 microns center-to-center distance between adjacent holes. A 60 Vpp amplitude square wave is applied to the piezo at the resonant frequency (108.0 kHz) causing the ejector plate to oscillate at approximately the same frequency.
When operating with these parameters, the device produces droplets with a size distribution in which the median diameter is 55 microns. In this example, it is assumed that the ideal range for the device is 3.0 cm orthogonally from the plane of the target. If the target has a bottom-to-top target diameter of 8.0 mm, then the average distance that a droplet could fall due to gravity before leaving the target is 4.0 mm. The terminal velocity for a 55 microns water droplet is 0.09 m/s. Therefore it takes at least 0.044 s to fall 4 mm. Assuming that the average horizontal velocity of a droplet is ½ the initial velocity, the minimum initial velocity needed to propel the droplet to a target 3.0 cm away in 0.44 s is 1.4 m/s.
Droplets with a diameter of 55 microns have an evaporation time of approximately 3 seconds. Therefore, a particle traveling at the minimum velocity needed to reach the eye would still contain greater than 99% of its initial volume upon impact with the eye. See, e.g.,
Without accounting for entrained air effects, the momentum to drag force ratio (relaxation time) of this median sized particle would be 0.0093 s, leading to a theoretical stopping distance of 9.3 mm. However entrained air reduces the drag force on droplets, increasing the effective range by up to one order of magnitude.
Measurement and analysis of particle diameter was performed with a Malvern Spraytec instrument. This system uses a 632.8 nm laser collimated to a 10 mm diameter beam. When the laser interacts with particles in its path, light is scattered at various angles depending on the droplet size. A lens focuses the scattered light onto photodiode detector elements. The control software subtracts electrical and optical background noise, applies a multiple scattering correction filter, and then calculates the droplet size distribution as a function of time.
Mass deposition experiments were performed with a 20 MHz BK Precision 4040A function generator, a NF Electronic Instruments 4025 high speed power amplifier/bipolar power supply, and an Ohaus Pioneer PA214 digital scale (210 g capacity×0.1 mg resolution). Glass slides (7.5 cm×7.5 cm) were used to collect droplets ejected from the Corinthian Ophthalmic drug delivery invention. These large slides are important to observe the effect of entrained air on mass deposition. An Edmund Optics 36 inch dovetail optical rail was used to vary the mass deposition distance while maintaining straight line accuracy.
Droplet size distributions were measured with the Malvern Spraytec instrument and software. A droplet generating device was maintained at a constant distance of 3.0 cm from the center of the collimated laser beam and sprayed horizontally into the beam. The function generator was used to drive the high speed power amplifier using pulse-width modulation. The high speed power amplifier produced a square wave with 108.0 kHz frequency, pulse width of 0.150 s, 50% duty cycle, and 60 Vpp amplitude, thereby driving the piezo at its resonant frequency. The Malvern Spraytec triggered to begin measurements when laser transmission dropped below 98%.
Dose effectiveness measurements were performed by observing the mass deposition on the glass slide at distances of 0.0-6.0 cm from the ejector plate. This experiment was performed on 5 different ejector plate hole sizes.
The graphs are normalized to 100% mass deposition, and plotted as a function of distance and median particle diameter as measured by the Malvern Spraytec device (
Droplets with insufficient mass will have a low momentum to drag force ratio as shown in equation 3. These droplets will create more entrained air relative to their diameter during their time of flight, because they have a larger surface to volume ratio. When these smaller droplets near the eye, they have an insufficient momentum to overcome the entrained air effect described above, and consequently are often deflected. Small droplets also have a shorter stopping distance. This factor contributes to their rapid deceleration before they reach the target. An evaporation rate is also higher for the droplets at the 17 microns diameter threshold. A higher evaporation rate helps to compound the problems of stopping distance, air entrainment, and momentum to drag force ratio.
Droplet diameters and mass deposition rates are measured at various distances. Droplets with diameter greater than or equal to 32 microns have a noticeably higher percentage of mass deposited. Particles with diameters less than or equal to 17 microns appear did not deposit significant mass over a wide range of distances. Droplets with diameters greater than or equal to 32 microns perform deposited mass at higher levels seem for diameters equal or less than 17 microns. See, for example,
In an implementation, a hand-held, portable ophthalmic dispenser typically is held about 3 cm from the eye as it creates fluid microspheres or micro droplets that travel to the eye of the user. Microspheres of the drug are formed and launched as a piezo material vibrates an ejection plate on the dispenser in a precise pattern of frequency and duration. A piezo material changes shape as a voltage is applied across it. A shape change is mechanically linked to vibrate the ejection plate. Size and velocity of the microspheres is critical so that spheres are not too small and slow moving that they fail to ready the eye. Similarly, quantities and mass of the spheres is important to maintain a correct dosage of drugs to the eye. Ejection plates are created by precise micro fabrication techniques. Microsphere diameter is related to diameter of holes in the ejection plate. Ejection plates will typically have hundreds of holes in the plate, all fabricated to have the same diameter with a nominal diameter typically between 15 microns and 60 microns.
In one implementation, the size of the microspheres ejected from such a plate will vary in volume according to the magnitude of plate motion. The frequency of the plate motion is determined by the frequency of an electrical voltage (typically a square wave) that actuates the piezo actuator attached to the ejector plate. Typically, the actuating voltage will be in the range of 100 kHz to 150 kHz and will have a duration of 10 milliseconds to 100 milliseconds per dose.
In one implementation, drug volume per dose is calculated from the diameter of the ejected spheres, number of holes in the plate, frequency of vibration, number of voltage cycles per ejection per hole, and length of time the plate is vibrated. For example, an ejection plate having 1000 holes that are 20 microns in diameter may eject spheres about 40 microns in diameter. If a sphere ejects from each hole about once per ten cycles then a 100 kHz vibration from the piezo will eject about 100,000/10 spheres per hole per second or about 10,000,000 spheres per second from all 1000 holes. If each sphere is 40 microns in diameter, then the ejector plate will dispense about 10,000,000*4/3*pi*((40e-6)/2)^3 cubic meters per second or about 10,000,000*4/3*pi*((40e-3)/2)^3=334 microliters per second. If the plate is actuated for 40 milliseconds, then about 13 microliters of drug are ejected.
While not to be limited by them, sphere size and velocity are related to the magnitude and frequency of the voltage applied to the piezo. In part, this is because magnitude of the ejector plate motion and piezo motion is related to frequency of the driving signal. Magnitude of the piezo motion is directly related to the voltage of the applied voltage. Ejection velocity is also dependent on the frequency and magnitude of the applied voltage. It has been found that the spheres are not ejected except in a fairly narrow range of frequency band with optimums for maximum speed and volume. Unfortunately, variation in manufacture of piezos causes this optimum to vary about 10% among a batch of piezos. This variation results in each dispense unit needing a slightly different voltage frequency to achieve the same dispense velocity and volume. Thus, each unit must be tuned during manufacture for a specific frequency. Typically, frequency rather than voltage is tuned due to the increase in circuit complexity and cost associated with having voltage control. On the other hand, control of the frequency of a square wave is accomplished by changing the frequency of the internal square wave generator (typically a microprocessor or FPGA).
In one implementation, in a portable device, voltage and power applied to the piezo is limited by breakdown voltages of electrical components and total battery energy. Thus, tuning for optimum ejection of spheres is required to achieve good ejection with minimum and maximum voltages. Tuning frequency slightly off the optimum allows control of the velocity of ejection for a given applied voltage. Similarly, total mass ejected per dose is controlled by the duration of ejection. Thus, a final tuning of driving frequency and driving time is needed to set ejection velocity and dose volume.
In one implementation, described here is a device and method for tuning the ejection velocity and dose size for a portable ophthalmic dispenser.
In one implementation, a small target plate with an associated weighing mechanism and a vision system that observes the region between the dispenser and target plate and a test fixture controller that initiates dispenses from the dispenser, receives the weight and velocity of the dispensed dose and calculated appropriate modifications to dispense constants in the ophthalmic delivery device. An ophthalmic dispenser has an externally programmable, internal controller with static memory (like EEPROM) to receive and store these constants.
In one implementation, the vision system will measure the velocity of the dispense. Typical dispense velocities are in the range of 0.5 to 5 meters per second or times to transit 5 cm of 10 to 100 milliseconds. Thus, a camera with a frame rate faster than 100 frames per second and ideally about 1000 frames per second would measure the leading edge of a dispense as it travels from the dispenser to the weighing station. Obviously, accuracy of measuring the front edge of the droplets depends upon an effective illumination source that is part of the vision system.
In one implementation, a dispenser will be placed in the tuning station in a rigid jig (or brought to the test area in a jig) with electrical connections to the dispenser. A dose will be dispensed toward the target about 3 cm away as the vision system measures the velocity of the front edge of the ejected droplets. Then, the target will be weighed. The controller then calculates the dispense volume and velocity. Typically, dispenses will be done at multiple frequencies to determine the optimal dispense frequency for correct droplet velocity. Dosage per dispense will be measured by the weighting system at this frequency and then dispense time will be set to a value that gives the correct dosage.
In one implementation, the dispense target approximates the area of an eye. At appropriate times, the dispense fluid is cleaned from the target with a blast of air followed by another weighing to tare the system. For accurate dose measurement, multiple dispenses may be done to increase the total mass measured.
In one implementation, a vision system can be used to verify the width of the dispense plume and even infer droplet size according to the degree to which the droplets are carried around the target by the airflow. This data can be collected in one or two directions (for example, from above or from the side) to verify aim of the dispense plate if needed. Similarly, a vision system that observes droplet flight from the side can infer dispense velocity and droplet size form the amount that the dispense falls below the target. With higher dispense velocities, the vertical position of the droplets will change less.
In one implementation, in order for this system to work, each portable device must have an externally programmable memory to hold the calibration constants for piezo frequency and duration. Additionally, for consumer and particularly prescription applications, each unit must be able to store the number of doses it is allowed to dispense. This is necessary because each unit will have to be slightly overfilled both to allow for calibration sprays and cleaning sprays which may occur each time the unit is opened. Furthermore, by the nature of a multi-hole ejector, it is necessary to have the entire ejector plate wetted for a full-dose dispense. The full wetting requirement will require that excess drug will have to be stored in the dispenser so that at the end of user dosing, there will be drug left in the dispenser.
In one implementation, the number of doses ejected can be restricted both for the consumer to prevent partial doses being used and for the supplier of the device so that per dose is accurately accomplished. For example, if a unit was 20% overfilled, then the consumer might buy 20% fewer units on an annual basis in the case of long-term use of the device.
In one implementation, along with calibration constants and dose limits, the memory may be programmable to allow the same unit to dispense different sized doses in the case where a smaller person or child should receive smaller doses of the drug. Similarly, in cases where the unit should alert the user if a dose is overdue, as in the case of a glaucoma medication where regular application of the drug is key to minimizing damage by the disease medication intervals and even an internal clock might be set. For example, during the day, doses might be required every 4 hours, but no doses are required from 9 pm to 6 am when the person is sleeping.
In one implementation, at the point of calibration of the dispense system, or later during packaging or prescription sales, the user constants might be downloaded to the device.
Although the foregoing describes various embodiments by way of illustration and example, the skilled artisan will appreciate that various changes and modifications may be practiced within the spirit and scope of the present application.
U.S. application Ser. No. 13/184,446, filed concurrently herewith, entitled “Ophthalmic Drug Delivery” and U.S. application Ser. No. 13/184,468, filed concurrently herewith, entitled “Method and System for Performing Remote Treatment and Monitoring” are also each herein incorporated by reference in their entireties.
The present application claims the benefit of the filing date of U.S. Provisional Application No. 61/400,864, filed Jul. 15, 2010, U.S. Provisional Application No. 61/401,850, filed Aug. 20, 2010, U.S. Provisional Application No. 61/401,920 filed Aug. 20, 2010, U.S. Provisional Application No. 61/401,918 filed Aug. 20, 2010, U.S. Provisional Application No. 61/401,848 filed Aug. 20, 2010, U.S. Provisional Application No. 61/401,849 filed Aug. 20, 2010, U.S. Provisional Application No. 61/462,576 filed Feb. 4, 2011, U.S. Provisional Application No. 61/462,791 filed Feb. 5, 2011, U.S. Provisional Application No. 61/463,280 filed Feb. 15, 2011, U.S. Provisional Application No. 61/516,462, filed Apr. 4, 2011, U.S. Provisional Application No. 61/516,496 filed Apr. 4, 2011, U.S. Provisional Application No. 61/516,495 filed Apr. 4, 2011, and U.S. Provisional Application No. 61/516,694, filed Apr. 6, 2011, the entire contents of each of which is specifically hereby incorporated by reference for all purposes. The present application is also related to U.S. Provisional Application No. 61/396,531 filed May 28, 2010, the entire contents of which is specifically hereby incorporated by reference for all purposes.
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