Patent Application
20150335911
The invention is related to the field of photodynamic therapy (PDT), and in particular to a light emitting system used in PDT.
In the medical device field there are numerous techniques to deliver light to perform a medical procedure, but the two most common techniques are direct and focused illumination. Direct illumination occurs with a bare or diffused light source placed a distance of several centimeters to meters from the patient. Direct Illumination devices are rarely attached to the patient. In general, the patient is required to position themselves to the illumination source. Examples of light delivery devices that fall within this category include conventional phototherapy units, such as the standard light box and hand/foot units that emit UV-A, UV-B or narrow-band UV-B light.
Phototherapy units are used primarily for the treatment of inflammatory skin diseases such as psoriasis. The units are also used in conjunction with orally or topically administered psoralens that photoactivate with UV-A light in the treatment of severe psoriasis and extensive vitilligo. This treatment is known as PUVA (psoralen UV-A) therapy. For systemic diseases such as cutaneous lymphoma, graft versus host disease and systemic sclerosis, extracorporeal photophoresis is performed where the patient ingests the psoralen and the blood is exposed to the UV-A light outside the body and then re-infused into the patient. The DUSA (blue visible light) and Galderma-Metvix (red visible light) systems are used for the treatment of actinic keratoses (pre-malignant skin growths) and superficial basal cell carcinomas. They work via topical aminolevulinic acid (DUSA) and methyl-aminolevulinic acid PDT.
Focused illumination, both internal and external to the patient treatment site requires illumination that has an optical system to direct light from the illumination device to specific areas onto the patient, typically in a controlled beam shape and beam intensity. In many cases the optical system is composed of one or more optical fibers that use total internal reflection to collect light at one end of the fiber, transmit the light, and exit with a specific numeric aperture at the other end. Typically this approach requires larger fibers or an array of large fibers to illuminate large areas (>5 mm). Illuminating more than a single fiber requires sophisticated coupling of the light into the fibers. This coupling is usually inefficient and can have very low coupling efficiency (<10% efficiency). Similar to direct illumination, the focused illumination approaches is rarely done where a patient wears a device.
For FDA approved PDT indications, there are numerous light illumination devices meeting the direct and focused illumination schemes. For example, for Barrett's esophageal cancer treated with PDT, a focused illumination system is implemented using a fiber optic cable attached to a FDA approved laser system such as the Angio Dynamics PDT 630 nm laser. Alternatively, a direct illumination approach to PDT for actinic keratosis is done using similar devices such as DUSA's Blue-Light Phototherapy Lamp or Galderma's Aktilite which is also used for basal cell carcinoma skin cancer.
There are few wearable medical based illumination devices except for the Ambicare Health Ambulight PDT device that only covers a small area and has no degree of flexibility or conformity to anatomical features. The device is a pad of LEDs that are placed directly on the treatment area. This method of delivery does allow the system to be portable, but it places the illumination source directly on the patient causing thermal side effects.
Another device that is wearable, but displaces the illumination source and any generated heat from the source at a distance from the treatment site is a weaved collection of fiber optic cables that are bent sharply at several locations along the length of the fiber. The bending of the fiber cause light to leak from the fiber illuminating a small portion of a light illumination surface that consists of hundreds to thousands of these bent fibers. This weaved fiber approach provides imprecise quantities of light at the treatment site because the bending (the mechanism of light leakage) of the fiber is not uniform from bend to bend and the location of bending along similarly aligned fibers can be random from fiber to fiber.
According to one aspect of the invention, there is provided a therapeutic light delivery system. The therapeutic light delivery system includes one or more fiber optic arrays that channels illumination from an illumination device. An optics module coupled to the one or more fiber optic arrays that provides the illumination to the one or more fiber optic arrays. A control module coupled to the optics module that controls the illumination to the one or more fibers. The illumination comprises a plurality of therapeutic patterns and wavelengths.
According to another aspect of the invention, there is provided a method for delivering light for wound care. The method includes providing one or more fiber optic arrays that channels illumination from an illumination device. Also, the method includes coupling an optics module to the one or more fiber optic arrays that provides the illumination to the one or more fiber optic arrays. Furthermore, the method includes controlling the illumination to the one or more fibers using a control module coupled to the optics module. The illumination comprises a plurality of therapeutic patterns and wavelengths.
The invention is a low power, wearable, non-coherent illumination device (ID) using Light Emitting Diode(s) (LED). Also, the invention includes design improvements for a light emitting patch (LEP) that precisely places the LEP on a patient for 24 hours without hindering movement and without wearing cumbersome holding devices as well as handling fluids that may be near the illumination treatment area.
The initial design investigation of the ID was to determine where best to place the ID or the LED(s) of the ID in relation to the LEP and the LEP's light emitting surface (LES). First, the illumination (a single LED or an array of LEDs) at the bottom of the LEP's LES was explored such that the ID would also be near the treatment site of the LEP. This design, although attractive in simplicity did have two problems for long therapy times. One, it moved a source of potential heat close to the treatment site and two, it didn't provide the same capability for scaling the bandage in size without having to scale the size of the ID.
Based on the above design considerations (heat and scalability), the LEP design forced the ID location to be placed away from the LEP and from the treatment site to a place where the unit can comfortably sit. It was found that RSI can easily place the ID on the belt line of a patient. With the illumination further away, it required that RSI transport the light from the belt line to the treatment site, with the easiest method to use the fiber optics in the LEP as this transport mechanism. Again, to simplify the design, the easiest method to move light from the ID into the fibers was to bring the fibers into a circular bundle that can butt-couple to the ID LED illumination source. To properly butt-couple the fiberoptic circular bundle and the optic of the LED (used to shape the illumination from the LED die and to match the numerical aperture, acceptance angle, of the fiberoptics) a spring-switch (canted-coil assembly) described below is used.
The spring switch provided several functional features to the unit. It properly located the LEP input to the ID LED, it provided a locking mechanism that keeps the LEP in place during treatment but also allows (with 3-5 lbs. of force) the User to easily remove the LEP from the ID, it provides 360-degree of rotation of the LEP in the ID, and it also creates a switch that will only light to exit the LED when the LEP is locked in place. By making the LEP and ID become a switch, the potential risk of the high intensity LED light source exiting the ID when there is no LEP coupled to the ID is reduced.
The illuminator uses off-the-shelf (OTS) commercially-available LED light source modules. A laser can be used but the LED is sufficient for low-power output applications and the light does not need to be coherent, although it could be if needed.
In the prior art, the illumination was pigtailed into a fiberoptic that was then expanded into a collimating optic which then was coupled into the fiberoptic patch array of the LEP. With the LED it was desired to remove the $250+ collimating optic. The invention provides a simple solution to shape the beam of light from the LEDs into a uniform field using an inexpensive plastic LED optic 2, as shown in
The ID unit 12 is designed using the LED optic 2 that was built on the square printed circuit board (PCB) 6. The LED optic 2 being placed on a round PCB 6 which is 0.81″ (20.5 mm) in diameter that allowed the ID to shrink in size and to enable the housing 10 to have a more flash-light shape and feel to the unit, as shown
Table 1 details the specifications on the LED module chosen for the ID system of
The ID unit 12 of
This locking mechanism 8 is a novel feature in the design of the ID unit 12 because it minimizes the risk of patient eye and thermal safety when the device has been turned ON by the User. The LED provides significantly more irradiance (˜1.4 mW/cm2) than the required 580 uW/cm2 that exits the 10 cm×10 cm output surface (LES) of the LEP due to light losses inherent in the system. This loss primarily comes from the butt-coupling of light from the LED to the LEP fiberoptics. Although the output of the LED without attachment to the LEP was deemed safe (through benchtop testing), it was imperative that patients do not: 1) look directly at the ID LED when the unit was turned ON and 2) try to use the device for other illumination needs beyond the phototherapy treatment. By placing a locking mechanism/switch into the unit, it locks the LEP into a well-defined standoff distance from the LED optic.
The locking mechanism or canted coil assembly 8 is composed of a canted-coil spring, a circular spring which is designed to produce a nearly constant force over the working spring deflection as opposed to traditional springs which have a spring force directly proportional to deflection. Canted coil springs can be used for latching, locking, and holding applications and can be customized based on diameter, connection (insertion and removal) force, and application use. An example of the canted coil spring 16 and its locking mechanism 8 is shown in
When the stainless steel piston 38 on the LEP 40 makes contact with the washer 32 and the metal spring holder 30, an electrical connection or switch 42 is made through the PCB 36 which can detect when this connection has been made. If the ID 24 is ON and the electrical connection is made, the LED 46 will be permitted to emit light. To make this electrical connection when the ID is ON, the metal contact surface of the LEP piston 38 has to maintain contact with the metal washer 32. A key benefit of this locking design is that it eliminates the user from having to directly control any shuttering, it avoids cumbersome switches, and it allows the LEP 40 to swivel an entire 360-degrees around the ID 24 because the LEP piston 38 can rotate freely within the spring 30 while maintaining a locking force and surface contact with the washer 32.
The ID units used in accordance with the invention can use D-Cell sized battery with significantly higher voltage (3.6V) and current (13.0 Ah) ratings than a standard commercial grade D-Cell battery and which can provide the required energy needed for 24 hours of CLIPT treatment. The battery is composed of Lithium Thionyl Chloride (Li—SOCl2) and RSI found several manufacturers with these batteries that had been tested to UL electrical and safety requirements. RSI's Rev 2 ID has since incorporated the Li—SOCl2 battery design and has undergone initial bench testing.
To control the power input and output of the battery, the LED and LED PCB, and the User functionality of the ID, the PCB used firmware and hardware controls to operate the device. The PCB, with double-sided populated electronics was shrunk to 1″×1″ and was attached to the back of a heatsink holding the IOI LED.
A main feature of the PCB is that all of the main components of the ID comprised of the battery connection, the power switch, the LED, and the spring-switch all connect to the PCB via Molex connections. Each part can be built separately and then attached at the end to the PCB before closing the entire assembly with the ID housing. The design of the PCB also allows the user to adjust the power output for future clinical studies that can explore higher or lower energy delivery by adjusting a potentiometer. Additionally, the design of the unit accounts for several time settings allowing us to turn Off the device at varying time settings including 15 minutes, 30 minutes, 45 minutes, 1 hour, 2 hours, 4 hours, 6 hours, 8 hours, 12 hours, and 24 hours.
The mechanical housing design was carefully designed to account for five interaction surfaces. 1) The housing made accommodations for the push-button power On/Off such that it can rest on one of the inner housing molds so that the unit can be assembled much easier. 2) The housing placed a small fiberoptic port over the LED Status light on the PCB to allow the User to see the LED Status indication light with clarity. 3) The battery door was designed several times using SLA molds and mock ups to get a comfortable but stable latching for User interaction when inserting and removing the battery. 4) The entrance port for the LEP was improved to allow the LEP to swivel around the ID to avoid any cable tangling and the entrance port was deepened to mitigate any risk from electrical contact with any switches, including the spring-switch. 5) The back of the ID was given some additional feature contours where a belt clip can be added to the unit.
The basic design of a LEP 52 can be seen in
The FOCs 54 in the array are typically placed in a one-dimensional (1D) arrangement where each FOC 54 in the array is parallel to one another. The placement of one FOC to another can be abutting, equally spaced, or non-linearly spaced. Each FOC is cut typically to a length of 24-48″ long to reach multiple locations on the body once the LEP is finally assembled.
The FOC 54 is commonly laid onto medical grade adhesive backed foam layer 56, a polyethylene foam single coated medical tape. Each FOC 54 will make contact and stick to the adhesive side of the foam layer 56. The foam layer 56 is usually cut as a square ranging in size, but a typical size is 100 mm×100 mm.
The foam/FOC layer is then attached to a fixed mechanical fixture inside a laser cutter. The mechanical fixture may be a vacuum chuck. A laser program that will deliver the optimal 1-D, 2-D, or 3-D fiber etch will be entered and run.
Following the etching of the fibers, the foam/FOC layer is removed from the laser cutter and will undergo further assembly. A second foam layer 58, which can be similar to the first foam layer 56 is placed on top of the open and exposed area on the FOC 54. Typically, on top of this second layer 58 is an opaque covering 60, like a black polyester sheet to block any light from exiting the LEP towards the user and other external observers. Note any one of the layers can have a diffusing patter or a diffuser on it to help aid in the light structure output that can make the light more uniform or to make custom patterns for a given application/—including wound care.
Typically a final layer 62 is added composed of an adhesive backed (acrylate adhesive developed for medical/surgical use) medical nonwoven tape. The adhesion of the material is 30 oz./inch which will allow it to stick a patient's skin or to other bandage and cast linings for long periods of time. The adhesive layer 62 can be cut in the middle to allow the foam/FOC/foam layer to be placed in the center and then covered with the adhesive layer's 62 liner, a poly-coated Kraft paper with silicone release on one side.
There are typically several epoxies used to lock down or tighten surfaces. Epoxy is typically used to adhere the bottom of the foam/FOC/foam layers with the Fiber Transition part as well as the silicone rubber sheathing with the Fiber Transition part and the piston. Fibers in the stainless steel piston are locked in place using EPOTEK 301 Epoxy and a potting station. After all the FOC 54 are rigid and in place, a diamond cutting device is used to sharply cut the fibers to have a common optical interface surface with few surface aberrations or minor surface deformations.
An important feature of the LEP is that it has bend radii in both the vertical and horizontal dimension that is less than 1.0 cm allowing for extreme flexibility on array of anatomical features while consistently providing constant illumination along these tight bends.
Another important feature of the LEP is the ability of the system to stick or adhere to skin or other objects by attaching fiberoptic cables and any surrounding layers that hold the fiberoptic channels in place to medical grade adhesive materials, epoxies, glues, or gel forming substrates.
Another important feature of the LEP is the absorption properties of the many layers holding the fiberoptic cables. These layers can absorb or wick away blood, fluids, and other substances that may result from a wound. These layers also allow the fiberoptics to remain clean and deliver light during wound care treatment. Additional methods to keep the fiberoptic cables clean may include the release of alcohols, solvents, or powders to reduce fluid buildup or drying blood, fluids, or substances on the fiberoptics. The spacing of the FOCs also helps pass blood, fluids, and substances past the fiberoptics and into the adjacent layers, particularly the foam layers that have absorption properties.
There are many different permeations of the LEP.
Note all the IDs described herein allows for the control of an illumination pattern by controlling the duration of the illumination, duration that wavelength is on/off, duration that a given wavelength is on/off per treatment, duration that a given wavelength is on/off per day, variation of irradiance (or Intensity) of each wavelength of light when a given wavelength is On, coordination of wavelengths when they're On, pulsing or continuous light output of any given wavelength, and variation in illumination pattern on the wound site from each wavelength.
The invention can utilize alternative embodiments or enhancements. For example, the light diffusion technology and fabrication process can be used to etch fibers that are embedded into bandages with or without adhesive. The fibers can be pre-etched and then adhered to either the adhesive or non-adhesive side of an adhesive bandage or applied directly to a non-adhesive bandage. The pre-etched fiber can also be embedded into the bandage. Alternatively, the fiber can be placed on any surface of a bandage or embedded in the bandage and then the bandage and fiber can be cut by the laser etching process. The laser etch cut may allow for mechanical features of the bandage while also creating the light diffusion pattern on the fibers.
The fibers can be placed on any surface of the proposed bandage or embedded but may be flexed in various geometric bending positions or be wrapped in circular loops to provide more flexibility to the bandage. These complex shapes can help provide various mechanical and human factor conditions that may not be met with a straight fiber.
The bandages with pre-etched or post-etched fiber optics cables can of many different aerial sizes but would ideally be 1 cm2, 5 cm2, 10 cm2, and 20 cm2 in size. The bandages with etched fibers can receive light from a fiber from an LED or laser light source. The fibers in the bandage can have a common input at one end of the bandage allowing for the coupling of the light through additional fiber optics or various other optical systems. The light bandage could be used in similar applications and medical indications used throughout this application.
The light bandage can receive light from a LED cartridge system. An array of LED modules can be coupled to a given bandage consecutively or simultaneously. The LED modules are worn around the shoulder like a harness or on the belt-line.
The layers described herein can be composed of a multitude of other layers or materials. The stack configuration of the layers can vary depending on the application. The number of layers can vary. One or more layers may provide additional features to the bandage, dressing, liner, cast, or fabric. For example, one layer may consist of a drug eluting surface that can release drug continuously or on a periodic basis. Drugs that might elute from one or more surfaces include nanoparticles, photosensitizers, antimicrobial drugs, oncology drugs, and other ointments. One or more layers may include antimicrobial coatings. One or more layers of the LEP may include microneedles that can puncture the skin using micron sized needles. These needles can deliver light, drugs such as photo sensitizers, or a combination of the light and drugs. The drugs can elute from the needles continuously or periodically.
The illumination device attached to the LEP can emit UV (260-400 nm), Visible to Near-Infrared (400-1000 nm), Near-Infrared (900-1700 nm) and Short-Wave Infrared (900-2500 nm) with the potential for Mid-Wave and Long-Wave Infrared illumination (2500 nm to 17,000 nm). The LEP or LEP can transport and delivery illumination over this spectral range of 260 nm to 17,000 nm. The illumination from the ID and the LEP LES can range from 0.001 mW/cm2 to 10,000 mW/cm2.
There are a multitude of other light delivery mechanisms that could be used to create the LES of the LEP. This can include new transparent polymer materials, silk, or new synthetic carbon grapheme or nanotube particles that can emit light.
In conjunction with the LEP and ID, there can be the addition of a monitoring sensor to monitor light input/output from the LEP fibers but also from the patient's anatomy or skin. The sensors can be used to monitor and control light dosimetry based on thermal criteria, bacteria load criteria, fluid levels, or other human-environmental conditions that may affect the healing process.
There are an array of other potential application for the LEP or LES. For example, the LEP can be combined with negative pressure wound therapy dressings to create a more effective therapy. In this use-case scenario, the vacuum dressing would be laced with etched optical fibers. The unit would be controlled with a single device that includes a negative pressure pump and an illumination device merged into one device.
The LEP and the etched fiber optic cables can also be laced into a traditional gauze for treating less severe chronic wound management needs. The LEP can use an optically transparent non-adhesive dressing such that light can be delivered external to the wound dressing, cast, lining and fabric to promote light mediated wound therapy. In this configuration, the light can be delivered by etched fiber optic cables or it could be delivered by an illumination source other than a fiber optic cable, such as an LED.
The transparent dressing would have several benefits such as helping reduce thermal issues, reducing the device or fibers from being in direct contact with wounds, providing improved sterility, and reducing biocompatibility issues. The LEP layers, including the transparent dressing have the potential for providing liquid growth factors in conjunction with the bandage to promote growth and healing faster and more effectively without the LEP or its material properties. The LEP can be used in brace lining for backs, knees, and legs.
The invention can be applied to traditional wound dressing to assist acute wound treatment. Minimally invasive surgery has replaced many open surgical procedures. Infections in the skin portals that communicate between the outside environment and internal body cavities, while rare can be devastating. In particular, the percutaneous power supply for left-ventricular assist devices (LVAD) is a frequent portal for infection that can be life-threatening. Patients often develop multiple drug-resistant infections due to the frequent and chronic use of antibiotics to prevent and treat these percutaneous line-infections. The invention can be configured to work with vacuum-dressings or conventional pressure/compression dressings.
Moreover, the invention can applied for treating diabetic ankle and foot ulcers, pressure/decubitus ulcers, soft casts—bone healing, as well as other similar remedies.
Although the present invention has been shown and described with respect to several preferred embodiments thereof, various changes, omissions and additions to the form and detail thereof, may be made therein, without departing from the spirit and scope of the invention.
This application claims priority from provisional application Ser. No. 62/000,770 filed May 20, 2014, which is incorporated herein by reference in its entirety.
| Number | Date | Country | |
|---|---|---|---|
| 62000770 | May 2014 | US |
