Patent Application
20210252285
Example inventions are directed to systems and methods for improving health by treating the symptoms of constipation and fecal incontinence.
Constipation refers to bowel movements that are infrequent or hard to pass. The stool is often hard and dry. Other symptoms may include abdominal pain, bloating, and feeling as if one has not completely passed the bowel movement. Complications from constipation may include hemorrhoids, anal fissure or fecal impaction. The normal frequency of bowel movements in adults is between three per day and three per week. Babies often have three to four bowel movements per day while young children typically have two to three per day.
Conversely, fecal incontinence (“FI”), or in some forms encopresis, is a lack of control over defecation, leading to involuntary loss of bowel contents, both liquid stool elements and mucus, or solid feces. When this loss includes flatus (gas) it is referred to as anal incontinence. FI is a sign or a symptom, not a diagnosis. Incontinence can result from different causes and might occur with either constipation or diarrhea.
A non-invasive nerve patch/activator in accordance with various examples disclosed herein includes novel circuitry to adequately boost voltage to a required level and to maintain a substantially constant level of charge for nerve activation. Further, a feedback loop provides for an automatic determination and adaptation of the applied charge level. In example inventions, the patch is used to treat the effects of constipation and fecal incontinence without the use of medications or surgically implanted devices.
Patch 100 is used to stimulate these nerves and is convenient, unobtrusive, self-powered, and may be controlled from a smartphone or other control device. This has the advantage of being non-invasive, controlled by consumers themselves, and potentially distributed over the counter without a prescription. Patch 100 provides a means of stimulating nerves without penetrating the dermis, and can be applied to the surface of the dermis at a location appropriate for the nerves of interest. In examples, patch 100 is applied by the user and is disposable.
Patch 100 in examples can be any type of device that can be fixedly attached to a user, using adhesive in some examples, and includes a processor/controller and instructions that are executed by the processor, or a hardware implementation without software instructions, as well as electrodes that apply an electrical stimulation to the surface of the user's skin, and associated electrical circuitry. Patch 100 in one example provides topical nerve activation/stimulation on the user to provide benefits to the user, including bladder management for an overactive bladder (“OAB”) or treating the effects of constipation and fecal incontinence.
Patch 100 in one example can include a flexible substrate, a malleable dermis conforming bottom surface of the substrate including adhesive and adapted to contact the dermis, a flexible top outer surface of the substrate approximately parallel to the bottom surface, a plurality of electrodes positioned on the patch proximal to the bottom surface and located beneath the top outer surface and directly contacting the flexible substrate, electronic circuitry (as disclosed herein) embedded in the patch and located beneath the top outer surface and integrated as a system on a chip that is directly contacting the flexible substrate, the electronic circuitry integrated as a system on a chip or discrete components and including an electrical signal generator integral to the malleable dermis conforming bottom surface configured to electrically activate the one or more electrodes, a signal activator coupled to the electrical signal generator, a nerve stimulation sensor that provides feedback in response to a stimulation of one or more nerves, an antenna configured to communicate with a remote activation device, a power source in electrical communication with the electrical signal generator, and the signal activator, where the signal activator is configured to activate in response to receipt of a communication with the activation device by the antenna and the electrical signal generator configured to generate one or more electrical stimuli in response to activation by the signal activator, and the electrical stimuli configured to stimulate one or more nerves of a user wearing patch 100 at least at one location proximate to patch 100. Additional details of examples of patch 100 beyond the novel details disclosed herein are disclosed in U.S. Pat. No. 10,016,600, entitled “Topical Neurological Stimulation”, the disclosure of which is hereby incorporated by reference.
One arrangement is to integrate a wide variety of these functions into a system on a chip 1000. Within this is shown a control unit 1002 for data processing, communications, transducer interface and storage, and one or more stimulators 1004 and sensors 1006 that are connected to electrodes 1008. Control unit 1002 can be implemented by a general purpose processor/controller, or a specific purpose processor/controller, or a special purpose logical circuit. An antenna 1010 is incorporated for external communications by control unit 1002. Also included is an internal power supply 1012, which may be, for example, a battery. Other examples may include an external power supply. It may be necessary to include more than one chip to accommodate a wide range of voltages for data processing and stimulation. Electronic circuits and chips will communicate with each other via conductive tracks within the device capable of transferring data and/or power.
Patch 100 interprets a data stream from control unit 1002 to separate out message headers and delimiters from control instructions. In one example, control instructions include information such as voltage level and pulse pattern. Patch 100 activates stimulator 1004 to generate a stimulation signal to electrodes 1008 placed on the tissue according to the control instructions. In another example, patch 100 activates transducer 1014 to send a signal to the tissue. In another example, control instructions cause information such as voltage level and a pulse pattern to be retrieved from a library stored by patch 100, such as storage within control unit 1002.
Patch 100 receives sensory signals from the tissue and translates them to a data stream that is recognized by control unit 1002. Sensory signals can include electrical, mechanical, acoustic, optical and chemical signals. Sensory signals are received by patch 100 through electrodes 1008 or from other inputs originating from mechanical, acoustic, optical, or chemical transducers. For example, an electrical signal from the tissue is introduced to patch 100 through electrodes 1008, is converted from an analog signal to a digital signal and then inserted into a data stream that is sent through antenna 1010 to the external control device. In another example an acoustic signal is received by transducer 1014, converted from an analog signal to a digital signal and then inserted into a data stream that is sent through the antenna 1010 to the external control device. In some examples, sensory signals from the tissue are directly interfaced to the external control device for processing.
In examples of patch 100 disclosed above, when being used for therapeutic treatment such as bladder management for OAB or treatment of constipation or fecal incontinence, there is a need to control the voltage by boosting the voltage to a selected level and providing the same level of charge upon activation to a mammalian nerve. Further, there is a need to conserve battery life by selectively using battery power. Further, there is a need to create a compact electronics package to facilitate mounting the electronics package on a relatively small mammalian dermal patch in the range of the size of an ordinary band aid.
Adaptive Circuit
To meet the above needs, examples implement a novel boosted voltage circuit that includes a feedback circuit and a charge application circuit.
Boosted voltage circuit 200 can replace an independent analog-controlled boost regulator by using a digital control loop to create a regulated voltage, output voltage 250, from the battery source. Output voltage 250 is provided as an input voltage to charge application circuit 300. In examples, this voltage provides nerve stimulation currents through the dermis/skin to deliver therapy for constipation or FI. Output voltage 250, or “VBoost”, at voltage output node 250, uses two digital feedback paths 220, 230, through controller 270. In each of these paths, controller 270 uses sequences of instructions to interpret the measured voltages at voltage monitor 226, or “VADC” and current monitor 234, or “IADC”, and determines the proper output control for accurate and stable output voltage 250.
Boosted voltage circuit 200 includes an inductor 212, a diode 214, a capacitor 216 that together implement a boosted converter circuit 210. A voltage monitoring circuit 220 includes a resistor divider formed by a top resistor 222, or “RT”, a bottom resistor 224, or “RB” and voltage monitor 226. A current monitoring circuit 230 includes a current measuring resistor 232, or “RI” and current monitor 234. A pulse width modulation (“PWM”) circuit 240 includes a field-effect transistor (“FET”) switch 242, and a PWM driver 244. Output voltage 250 functions as a sink for the electrical energy. An input voltage 260, or “VBAT”, is the source for the electrical energy, and can be implemented by power 1012 of
PWM circuit 240 alters the “on” time within a digital square wave, fixed or variable frequency signal to change the ratio of time that a power switch is commanded to be “on” versus “off.” In boosted voltage circuit 200, PWM driver 244 drives FET switch 242 to “on” and “off” states.
In operation, when FET switch 242 is on, i.e., conducting, the drain of FET switch 242 is brought down to Ground/GND or ground node 270. FET switch 242 remains on until its current reaches a level selected by controller 270 acting as a servo controller. This current is measured as a representative voltage on current measuring resistor 232 detected by current monitor 234. Due to the inductance of inductor 212, energy is stored in the magnetic field within inductor 212. The current flows through current measuring resistor 232 to ground until FET switch 242 is opened by PWM driver 244.
When the intended pulse width duration is achieved, controller 270 turns off FET switch 242. The current in inductor 212 reroutes from FET switch 242 to diode 214, causing diode 214 to forward current. Diode 214 charges capacitor 216. Therefore, controller 270 controls the voltage level at capacitor 216.
Output voltage 250 is controlled using an outer servo loop of voltage monitor 226 and controller 270. Output voltage 250 is measured by the resistor divider using top resistor 222, bottom resistor 224, and voltage monitor 226. The values of top resistor 222 and bottom resistor 224 are selected to keep the voltage across bottom resistor 224 within the monitoring range of voltage monitor 226. Controller 270 monitors the output value from voltage monitor 226.
Charge application circuit 300 includes a pulse application circuit 310 that includes an enable switch 314. Controller 270 does not allow enable switch 314 to turn on unless output voltage 250 is within a desired upper and lower range of the desired value of output voltage 250. Pulse application circuit 310 is operated by controller 270 by asserting an enable signal 312, or “VSW”, which turns on enable switch 314 to pass the electrical energy represented by output voltage 250 through electrodes 320. At the same time, controller 270 continues to monitor output voltage 250 and controls PWM driver 244 to switch FET switch 242 on and off and to maintain capacitor 216 to the desired value of output voltage 250.
The stability of output voltage 250 can be increased by an optional inner feedback loop through FET Switch 242, current measuring resistor 232, and current monitor 234. Controller 270 monitors the output value from current monitor 234 at a faster rate than the monitoring on voltage monitor 226 so that the variations in the voltages achieved at the cathode of diode 214 are minimized, thereby improving control of the voltage swing and load sensitivity of output voltage 250.
In one example, a voltage doubler circuit is added to boosted voltage circuit 200 to double the high voltage output or to reduce voltage stress on FET 242. The voltage doubler circuit builds charge in a transfer capacitor when FET 242 is turned on and adds voltage to the output of boosted voltage circuit 200 when FET 242 is turned off.
As described, in examples, controller 270 uses multiple feedback loops to adjust the duty cycle of PWM driver 244 to create a stable output voltage 250 across a range of values. Controller 270 uses multiple feedback loops and monitoring circuit parameters to control output voltage 250 and to evaluate a proper function of the hardware. Controller 270 acts on the feedback and monitoring values in order to provide improved patient safety and reduced electrical hazard by disabling incorrect electrical functions.
In some examples, controller 270 implements the monitoring instructions in firmware or software code. In some examples, controller 270 implements the monitoring instructions in a hardware state machine.
In some examples, voltage monitor 226 is an internal feature of controller 270. In some examples, voltage monitor 226 is an external component, which delivers its digital output value to a digital input port of controller 270.
In some examples, current monitor 234 is an internal feature of controller 270. In some examples, current monitor 234 is an external component, which delivers its digital output value to a digital input port of controller 270.
An advantage of boosted voltage circuit 200 over known circuits is decreased component count which may result in reduced costs, reduced circuit board size and higher reliability. Further, boosted voltage circuit 200 provides for centralized processing of all feedback data which leads to faster response to malfunctions. Further, boosted voltage circuit 200 controls outflow current from VBAT 260, which increases the battery's lifetime and reliability.
The pulse width modulation of FET switch 242 is controlled by one or more pulses for which the setting of each pulse width allows more or less charge to accumulate as a voltage at capacitor 216 through diode 214. This pulse width setting is referred to as the ramp strength and it is initialized at 410. Controller 270 enables each pulse group in sequence with a pre-determined pulse width, one stage at a time, using a stage index that is initialized at 412. The desired ramp strength is converted to a pulse width at 424, which enables and disables FET switch 242 according to the pulse width. During the intervals when FET switch 242 is “on”, the current is measured by current monitor 234 at 430 and checked against the expected value at 436. When the current reaches the expected value, the stage is complete and the stage index is incremented at 440. If the desired number of stages has been applied 442, then the functionality is complete. Otherwise, the functionality continues to the next stage at 420.
As a result of the functionality of
An open loop protocol to control current to electrodes in known neural stimulation devices does not have feedback controls. It commands a voltage to be set, but does not check the actual current delivered. A stimulation pulse is sent based on preset parameters and cannot be modified based on feedback from the patient's anatomy. When the device is removed and repositioned, the electrode placement varies. Also the humidity and temperature of the anatomy changes throughout the day. All these factors affect the actual charge delivery if the voltage is preset. Charge control is a patient safety feature and facilitates an improvement in patient comfort, treatment consistency and efficacy of treatment.
In contrast, examples of patch 100 includes features that address these shortcomings using controller 270 to regulate the charge applied by electrodes 320. Controller 270 samples the voltage of the stimulation waveform, providing feedback and impedance calculations for an adaptive protocol to modify the stimulation waveform in real time. The current delivered to the anatomy by the stimulation waveform is integrated using a differential integrator and sampled and then summed to determine the actual charge delivered to the user for a treatment, such as OAB or constipation and fecal incontinence treatment. After every pulse in a stimulation event, this data is analyzed and used to modify, in real time, subsequent pulses.
This hardware adaptation allows a firmware protocol to implement the adaptive protocol. This protocol regulates the charge applied to the body by changing output voltage (“VBOOST”) 250. A treatment is performed by a sequence of periodic pulses, which deliver charge into the body through electrodes 320. Some of the parameters of the treatment are fixed and some are user adjustable. The strength, duration and frequency may be user adjustable. The user may adjust these parameters as necessary for comfort and efficacy. The strength may be lowered if there is discomfort and raised if nothing is felt. The duration can be increased if the maximum acceptable strength results in an ineffective treatment.
Adaptive Protocol
A flow diagram in accordance with one example of the adaptive protocol disclosed above is shown in
The mathematical expression of this protocol is as follows: Qtarget=Qtarget (A*dS+B*dT), where A is the Strength Coefficient—determined empirically, dS is the user change in Strength, B is the Duration Coefficient—determined empirically, and dT is the user change in Duration.
The adaptive protocol includes two phases in one example: Acquisition phase 500 and Reproduction phase 520. Any change in user parameters places the adaptive protocol in the Acquisition phase. When the first treatment is started, a new baseline charge is computed based on the new parameters. At a new acquisition phase at 502, all data from the previous charge application is discarded. In one example, 502 indicates the first time for the current usage where the user places patch 100 on a portion of the body and manually adjusts the charge level, which is a series of charge pulses, until it feels suitable, or any time the charge level is changed, either manually or automatically. The treatment then starts. The mathematical expression of this function of the application of a charge is as follows:
The charge delivered in a treatment is
Where T is the duration; f is the count of pulses for one treatment (e.g., Hertz or cycles/second) of “Rep Rate”; Qpulse (i) is the measured charge delivered by Pulse (i) in the treatment pulse train provided as a voltage MON_CURRENT that is the result of a Differential Integrator circuit shown in
As shown in of
In some examples, Analog to Digital Conversion 710 is an internal feature of controller 270. In some examples, Analog to Digital Conversion 710 is an external component, which delivers its digital output value to a digital input port on Controller 270.
At 504 and 506, every pulse is sampled. In one example, the functionality of 504 and 506 lasts for 10 seconds with a pulse rate of 20 Hz, which can be considered a full treatment cycle. The result of Acquisition phase 500 is the target pulse charge of Qtarget.
The reproduction phase 520 begins in one example when the user initiates another subsequent treatment after acquisition phase 500 and the resulting acquisition of the baseline charge, Qtarget. For example, a full treatment cycle, as discussed above, may take 10 seconds. After, for example, a two-hour pause as shown at wait period 522, the user may then initiate another treatment. During this phase, the adaptive protocol attempts to deliver Qtarget for each subsequent treatment. The functionality of reproduction phase 520 is needed because, during the wait period 522, conditions such as the impedance of the user's body due to sweat or air humidity may have changed. The differential integrator is sampled at the end of each Pulse in the Treatment. At that point, the next treatment is started and the differential integrator is sampled for each pulse at 524 for purposes of comparison to the acquisition phase Qtarget. Sampling the pulse includes measuring the output of the pulse in terms of total electric charge. The output of the integrator of
NUM_PULSES=(T*f)
After each pulse, the observed charge, Qpulse(i), is compared to the expected charge per pulse.
Q
pulse(i)>Qtarget/NUM_PULSES?
The output charge or “VBOOST” is then modified at either 528 (decreasing) or 530 (increasing) for the subsequent pulse by:
dV(i)=G[Qtarget/NUM_PULSES−Qpulse(i)]
where G is the Voltage adjustment Coefficient—determined empirically. The process continues until the last pulse at 532.
A safety feature assures that the VBOOST will never be adjusted higher by more than 10%. If more charge is necessary, then the repetition rate or duration can be increased.
In one example a boosted voltage circuit uses dedicated circuits to servo the boosted voltage. These circuits process voltage and/or current measurements to control the PWM duty cycle of the boosted voltage circuit's switch. The system controller can set the voltage by adjusting the gain of the feedback loop in the boosted voltage circuit. This is done with a digital potentiometer or other digital to analog circuit.
In one example, in general, the current is sampled for every pulse during acquisition phase 500 to establish target charge for reproduction. The voltage is then adjusted via a digital potentiometer, herein referred to as “Pot”, during reproduction phase 520 to achieve the established target_charge.
The digital Pot is calibrated with the actual voltage at startup. A table is generated with sampled voltage for each wiper value. Tables are also precomputed storing the Pot wiper increment needed for 1 v and 5 v output delta at each pot level. This enables quick reference for voltage adjustments during the reproduction phase. The tables may need periodic recalibration due to battery level.
In one example, during acquisition phase 500, the data set=100 pulses and every pulse is sampled and the average is used as the target_charge for reproduction phase 520. In general, fewer pulses provide a weaker data sample to use as a basis for reproduction phase 520.
In one example, during acquisition phase 500, the maximum data set=1000 pulses. The maximum is used to avoid overflow of 32 bit integers in accumulating the sum of samples. Further, 1000 pulses in one example is a sufficiently large data set and collecting more is likely unnecessary.
After 1000 pulses for the above example, the target_charge is computed. Additional pulses beyond 1000 in the acquisition phase do not contribute to the computation of the target charge. In other examples, the maximum data set is greater than 1000 pulses when longer treatment cycle times are desired.
In one example, the first 3-4 pulses are generally higher than the rest so these are not used in acquisition phase 500. This is also accounted for in reproduction phase 520. Using these too high values can result in target charge being set too high and over stimulating on the subsequent treatments in reproduction phase 520. In other examples, more advanced averaging algorithms could be applied to eliminate high and low values.
In an example, there may be a safety concern about automatically increasing the voltage. For example, if there is poor connection between the device and the user's skin, the voltage may auto-adjust at 530 up to the max. The impedance may then be reduced, for example by the user pressing the device firmly, which may result in a sudden high current. Therefore, in one example, if the sample is 500 mv or more higher than the target, it immediately adjusts to the minimum voltage. This example then remains in reproduction phase 520 and should adjust back to the target current/charge level. In another example, the maximum voltage increase is set for a single treatment (e.g., 10V). More than that is not needed to achieve the established target_charge. In another example, a max is set for VBOOST (e.g., 80V).
In various examples, it is desired to have stability during reproduction phase 520. In one example, this is accomplished by adjusting the voltage by steps. However, a relatively large step adjustment can result in oscillation or over stimulation. Therefore, voltage adjustments may be made in smaller steps. The step size may be based on both the delta between the target and sample current as well as on the actual VBOOST voltage level. This facilitates a quick and stable/smooth convergence to the target charge and uses a more gradual adjustments at lower voltages for more sensitive users.
The following are the conditions that may be evaluated to determine the adjustment step.
In other examples, new treatments are started with voltage lower than target voltage with a voltage buffer of approximately 10%. The impedance is unknown at the treatment start. These examples save the target_voltage in use at the end of a treatment. If the user has not adjusted the strength parameter manually, it starts a new treatment with saved target_voltage with the 10% buffer. This achieves target current quickly with the 10% buffer to avoid possible over stimulation in case impedance has been reduced. This also compensates for the first 3-4 pulses that are generally higher.
As disclosed, examples apply an initial charge level, and then automatically adjust based on feedback of the amount of current being applied. The charge amount can be varied up or down while being applied. Therefore, rather than setting and then applying a fixed voltage level throughout a treatment cycle, implementations of the invention measure the amount of charge that is being input to the user, and adjust accordingly throughout the treatment to maintain a target charge level that is suitable for the current environment.
The Adaptive Circuit described above provides the means to monitor the charge sent through the electrodes to the user's tissue and to adjust the strength and duration of sending charge so as to adapt to changes in the impedance through the electrode-to-skin interface and through the user's tissue such that the field strength at the target nerve is within the bounds needed to overcome the action potential of that nerve at that location and activate a nerve impulse. These changes in impedance may be caused by environmental changes, such as wetness or dryness of the skin or underlying tissue, or by applied lotion or the like; or by tissue changes, such as skin dryness; or by changes in the device's placement on the user's skin, such as by removing the patch and re-applying it in a different location or orientation relative to the target nerve; or by combinations of the above and other factors.
The combined circuits and circuit controls disclose herein generate a charge that is repeated on subsequent uses. The voltage boost conserves battery power by generating voltage on demand. The result is an effective and compact electronics package suitable for mounting on or in a fabric or similar material for adherence to a dermis that allows electrodes to be placed near selected nerves to be activated.
Constipation and Fecal Incontinence System and Treatment
In some example inventions, patch 100, disclosed above, is used for treatment of constipation and fecal incontinence by causing change in the physiology of the body. Example inventions provide an integrated system, including patch 100, which may be placed on the skin of the user to selectively stimulate posterior tibial nerves in the foot or leg. The system generates transcutaneous stimulation of the tibial nerve. Transcutaneous nerve stimulation increases both afferent and efferent nerve activity and tissue actions related to constipation and related to fecal incontinence.
Fecal incontinence can be divided into those people who experience a defecation urge before leakage (urge incontinence), and those who experience no sensation before leakage (passive incontinence or soiling). Urge incontinence is characterized by a sudden need to defecate, with little time to reach a toilet. Often people with anal incontinence have both urge and passive incontinence as well as constipation. In summary, FI can be passive, urge, or both in varying combinations and degrees.
Pathophysiology
Fecal incontinence occurs when the normal anatomy or physiology which maintains the structure and function of the anorectal unit is disrupted. Incontinence usually results from the interplay of multiple pathogenic mechanisms and is rarely attributable to a single factor. The internal anal sphincter (“IAS”) provides most of the resting anal pressure and is reinforced during voluntary squeeze by the external anal sphincter (“EAS”), the anal mucosal folds, and the anal endovascular cushions.
Disruption or weakness of the EAS can cause urge-related or diarrhea-associated fecal incontinence. Damage to the endovascular cushions may produce a poor anal “seal” and an impaired anorectal sampling reflex. The ability of the rectum to perceive the presence of stool leads to the rectoanal contractile reflex response, an essential mechanism for maintaining continence.
Pudendal neuropathy can diminish rectal sensation and lead to excessive accumulation of stool, causing fecal impaction, mega-rectum, and fecal overflow. The puborectalis muscle plays an integral role in maintaining the anorectal angle. Its nerve supply is independent of the sphincter and is part of the Levitor Ani nerve. Obstetric trauma, the most common cause of anal sphincter disruption, may involve the EAS, the IAS, and the pudendal nerves, singly or in combination.
Reflexes
The mechanisms and factors contributing to normal continence are multiple and inter-related. The puborectalis sling, forming the anorectal angle, shown in
The rectoanal inhibitory reflex (“RAIR”) is an involuntary IAS relaxation in response to rectal distension, allowing some rectal contents to descend into the anal canal where it is brought into contact with specialized sensory mucosa to detect consistency. RAIR causes a small contraction of the EAS to preserve continence upon first feces entering the rectum.
The intrinsic defecation reflex is triggered by rectal distension, which is sensed by stretch receptors in the rectal wall. This sends signals via afferent nerves to the myenteric plexus in the brain. Efferent nerves descend from the brain to control smooth motor output from the descending colon, the sigmoid colon and the rectum.
The parasympathetic defecation reflex is also triggered by rectal distension, using similar stretch receptors and afferent nerves at S2 to S4. The reflex returns along efferent nerves from S2 to S4 to control smooth motor output from the descending colon, the sigmoid colon and the rectum. The result of this reflex is a strong peristaltic wave which forces the feces downward toward the anus and relaxes the internal anal sphincter.
The rectoanal excitatory reflex (“RAER”) is an initial, semi-voluntary contraction of the EAS and puborectalis, which in turn prevents incontinence following the RAIR.
Other factors include the specialized anti-peristaltic function of the last part of the sigmoid colon, which keeps the rectum empty most of the time, sensation in the lining of the rectum and the anal canal to detect when there is stool present, its consistency and quantity; and the presence of normal rectoanal reflexes and defecation cycle, as described above, which completely evacuate stool from the rectum and anal canal.
Problems affecting any of these mechanisms and factors may be involved in the cause of FI.
Posterior Tibial Nerve Stimulation
Action potentials are communicated to the spinal cord at the levels of L4-S3 as part of the sciatic nerve by electrical stimulation of the afferent posterior tibial nerve. The pudendal nerve controls the EAS. It enters the sacrum at S2-S4. The levator ani nerve controls muscles including the puborectalis. It enters the sacrum at S4-S5.
The causes of FI and constipation are multi-factorial and can be related to dysfunction in one or more of the components of anorectal system. Some examples of components that may suffer dysfunction are: (1) External anal sphincter; (2) Pudendal nerve; (3) Myenteric plexus; (4) Afferent pathways to the cortex; (5) Processing in the brain; (6) Descending inhibitory or excitatory pathways from the cortex; and (7) Communications with the enteric nervous system.
Both sacral nerve stimulation (“SNS”) and posterior tibial nerve stimulation (“PTNS”) have been demonstrated clinically to be effective in the resolution of a majority of the cases of chronic FI or constipation.
Electrical stimulation of the afferent axons of the posterior tibial nerve, ipsilaterally or bilaterally, affects the pudendal nerve through reflex actions in the S3 vertebrae, and potentially others in adjacent S2, S4 vertebrae. It has been documented that pudendal neuropathy, besides reducing anal sensations, results in urge FI. A repeated exercise of a reflex between the tibial afferent nerve and the efferent pudendal nerve can provide more efficacious control of the EAS over time. Such treatment may require several stimulation sessions of minutes each over weeks to improve the pudendal voluntary and involuntary control of the EAS.
An unusual and seemingly paradoxical property of SNS is its efficacy in treating constipation and idiopathic urinary retention (Fowler Syndrome) by using stimulation at the same location and with the same stimulus parameters that are effective in treating bowel and bladder incontinence, which occurs mainly in women, is characterized by a loss of bladder sensations and the inability to voluntarily empty the bladder. It is associated with abnormal EUS activity and failure of the sphincter to relax during micturition. It is thought that tonic afferent firing arising in the sphincter inhibits the transmission of normal bladder sensory information to the brain. Functional magnetic resonance imaging (“fMRI”) studies revealed that SNS removes the inhibition and restores normal sensations and voiding. Thus, the actions of SNS can be influenced by pathological conditions.
SNS can suppress abnormal sensory pathways in patients with overactive bladder but can enhance normal sensory pathways that are tonically suppressed in patients with urinary retention. The same effect is true for PTNS. A significant percentage of FI relates to dysfunction of the EAS, and PTNS can indirectly stimulate the EAS through reflex actions.
For example, the stimulation of the tibial nerve will help to return the EAS to normal function with repeated treatments over time. The basic reflex arc exists for the Tibial Nerve to enter the dorsal horn of S3 and through one or more interneurons synapse on the pudendal nerve in Onuf's nucleus, which exits the ventral horn of S3 and descends to control the EAS.
For example, PTNS will stimulate many interneurons in the spinal cord, which will have an effect on ascending afferent pathways to the cortex, on descending inhibitory and excitatory pathways from the cortex, and on nerve communications with the enteric nervous system.
For example, electrical stimulation has been demonstrated to initiate angiogenesis and re-innervation of nerves. These will have an effect on the components of the anal-rectal system.
The Patch
Patch 100 is designed in a shape to conform to the skin when affixed to the skin and to be electronically effective at activating one or more branches of the posterior tibial nerve 810 using electrical fields. Patch 100 is electronically most effective when the positive and negative electrodes are placed axially along the path of the nerve, in contrast to transversely across the path of the nerve, which is not as electronically effective. Patch 100 can be placed below the ankle bone 101 of the left or right leg.
Patch 100 is a self-contained device capable of providing stimulation to the tibial nerve from the position at which it is affixed to the skin, over the duration of a session and at an intensity as set by the user. Once the stimulation has begun, on command from the user, the user need perform no additional action.
As a self-contained device, patch 100 has no lead wires, no external controller, and no external power source. Rather than placing two individual electrodes to the skin, the user affixes the patch 100, at the specified location. As a result, the user is free to move about during the treatment, unrestrained by wires or external devices. Patch 100 may be worn unobtrusively.
In some examples, patch 100 uses one electrode pair 114 to activate the nerve one or more legs. In some examples, patch 100 uses multiple positive electrodes and one or more negative electrodes to activate one or more branches of the nerve, modifying the waveshapes or timings, or both, of the stimulation pulses from the multiple electrodes to direct the waveform energy at one or more specific points on the nerves. Various arrays of electrodes as disclosed above can be controlled to generate optimized stimulation.
Stimulation Protocol for Constipation and Fecal Incontinence Treatment
In examples, the electrical stimulation is applied to the user's skin when started by the user after the user has affixed patch 100 to the skin according to the instructions for use.
Each stimulation session includes electrical stimulation at an energy level comfortable for each user, adjustable by the user at the beginning of the session, and at a pulse frequency between 10 Hz and 60 Hz, and at a pulse width of 100 microseconds to 400 microseconds, and a session duration of 5 to 30 minutes. In examples, each session duration is approximately 20 minutes, and user may undergo 3 treatments per day to have an optimal result. However, in general, treatment and resulting repair times will vary between individuals. As a result of an accumulation of treatment sessions, the muscles involved in normal defecation (i.e., the IAS, the puborectalis muscle, and the EAS) will eventually be “toned” and the healing or strengthening of nerves related to incontinence. The stimulation can be initiated and/or adjusted via a smart controller (e.g., smartphone) or fob that is in communications with patch 100.
The stimulation directly affects the tibial nerve, which has been shown to affect the sacral nerve and to increase blood flow centrally. The stimulation for the duration of the session affects the physiology in the pelvic area as well as the cortex, which senses the pelvic visceral changes. The effects on the cortex create an improved awareness of incontinence symptoms, to the point where the person changes their behavior and reduces the incidence of fecal incontinence.
In examples, each pulse has a pulse high time 4420, a pulse low time 4422, a pulse period 4424, and a pulse amplitude 4426. Pulses 4410 may be monopolar pulses or bipolar pulses 4440. For monopolar pulses, the pulse period 4424 is the sum of the pulse high time 4420 and the pulse low time 4422. Bipolar pulses have a negative pulse width 4442 and a negative pulse amplitude 4444, for the purpose of balancing the DC bias of the sequence of stimulation pulses, and for the purpose of balancing for zero net energy into the tissues. The negative pulse width may differ from the pulse high time. The negative pulse amplitude may differ from the pulse amplitude. Pulse shapes are affected by the impedance coupling to the user's tissues and by the patch 3010 output impedance, internal drive strength, and other factors, such that the pulses, whether monopolar or bipolar, may not be square waves.
One or more of the pulse high time 4420, the pulse low time 4422, the pulse period 4424, and the pulse amplitude 4426 may be adjusted. For bipolar pulses 4440, the negative pulse width 4442 and negative pulse amplitude 4444 may be adjusted from one user to another user, or from one application of a device to another on the same user. The pulse pattern may be adjusted during the course of a treatment.
Pulses may be output in bursts 4430. Each burst has two or more pulses 4410, or bipolar pulses 4440. Each burst has a burst pulse count 4432 and a burst period 4434. One or both of the burst pulse count and the burst period are adjustable for each user, or from one application of a device to another on the same user. The pulse frequency is the inverse of the pulse period. The burst frequency is the inverse of the burst period.
Pulses or bursts may be adjusted by each user each time a patch 100 is applied, since effective intensity may be different according to skin condition, dampness, dryness, weight change, specific location of placement and other factors. In this manner, the electrical pattern of stimulation pulses is adjusted for each application/treatment.
In examples, the pulses within one burst may all be of equal width. In examples, the pulses within one burst may be of varying widths, the width adjusted to optimize the stimulation for effectiveness.
In examples, the pulses within one burst may be evenly spaced. In examples, the pulses within one burst may be unevenly spaced. In examples, the pulses within one burst may have consistent amplitude. In examples, the pulses within one burst may have unequal amplitudes.
As such, the intensity of the applied pulses is adjusted for each user and may be adjusted and applied by each user each time patch 100 is applied, since effective intensity may be different according to skin condition, dampness, dryness, weight change, specific location of placement and other factors. In this manner, the electrical pattern of stimulation pulses is adjusted for each application.
In an example, one or more of pulse rise time, pulse fall time, pulse overshoot, and pulse undershoot are adjusted by one or both of patch 100 and the smart controller. Changes in pulse shape, including one or more of rise time, fall time, overshoot and undershoot, allow the patch to optimize use of power during the application of a treatment protocol. Optimizing the power used in a treatment allows a patch with a given design to apply more stimulation when compared to a patch without the means to optimize power delivery. Pulse shape is limited by one or both of patch and smart controller such that delivered energy, rate of energy delivery, magnitude of currents and/or voltages all meet the requirements for effective nerve stimulation at the applied position.
In an example, one or both of patch 100 and the smart controller operate to select one of a variety of hardware configurations, each hardware configuration on the patch specified to limit one or more of pulse rise time, pulse fall time, pulse overshoot, and pulse undershoot. One example uses a bank of capacitors, switched into the pulse application circuit under control of the patch, to optimize the load and its effect on the driven pulse voltage and current. A second example uses a bank of inductive loads. A third example uses a bank of resistive loads.
Electrode Arrangements
In examples, patch can use multiple positive electrodes in an array or matrix and also include multiple negative electrodes. Each positive electrode creates an electric field with the negative electrode nearest to it, such that the charge flows from one electrode to the other. Each positive electrode's field is not affected by other negative or positive electrodes, as these other electrodes are electrically distant from the positive electrode and the negative electrode. However, this set of electrodes may complicate the physical and electrical layout of the patch.
Therefore, in example inventions, a set of positive electrodes instead shares only one common negative electrode, such that the return current path back to the stimulating circuit is through the one negative electrode. This common negative electrode is larger than individual negative electrodes for each positive electrode when considering the two approaches on a fixed patch area. By making the common negative electrode larger, its impedance can be lower to the skin, its fringe area is minimized such that uncomfortable stimulation sensations are minimized when compared to current paths through small electrodes, and leakage currents are minimized because the single, larger negative electrode may be more easily isolated from circuitry than a multiplicity of negative electrodes.
The set of positive electrodes may be connected to the stimulating circuit one at a time or more than one at a time, using low-impedance switches between the shared voltage generating stimulation circuit and the individual electrodes. The controller controls the switches, such that only the desired positive electrode or electrodes are connected at one time.
The patch may use one positive electrode and a set of negative electrodes. The positive electrode is driven by the voltage for stimulation, using one circuit and working through the lower impedance of the large, common positive electrode in its contact with the skin. The negative electrodes may be a common ground, and connected to each other by conductive paths on the patch and further back to the stimulating circuit to complete the current loop. Alternatively, each negative electrode may be connected to the common ground through a low-impedance switch, the switches being under control of the controller, such that only the desired negative electrode or electrodes are connected to ground at one time, thereby limiting the return current path.
The set of positive electrodes driven by a stimulation voltage may have individually adjusted stimulation voltages such that, when connected and stimulating the skin, the combined stimulation from multiple positive electrodes is more effective than identical stimulation waveforms from all positive electrodes. The currents from each of the positive electrodes passes through the common negative electrode and back to the stimulating circuit. Individual stimulating circuits create individual stimulating waveforms which have specific setups under control of the controller. The controller may adjust the amplitude, phase, pulse width, and frequency of each circuit to create a combination of stimulation through multiple positive electrodes.
Sensing
As discussed, patch 100 may include one or more sensors. The sensors can be used to sense whether the user is suffering from constipation or FI. For example, sensors on patch 100 can measure human activity for such activities as trips to the bathroom (e.g., GPS and time in a location, or step count down the hallway to the bathroom) following a baseline pattern development using analytics and AI algorithms. The sensors can measure skin impedance and electromyography (“EMG”) signals which over time can give an indication of the user's sweating or feelings of urge to defecate or constipate. A treatment session can be automatically initiated or ended based on the sensing. Because constipation and FI is related to muscle contractions and muscle activity, it can be sensed by several means including EMG, accelerometers, skin temperature, or audio cues. The sensors can allow a baseline to be established before treatment, and the sensors can be then used as treatment progresses to detect changes. Further, the feedback provided by the sensors during the treatment can be used to adjust treatment parameters to improve the outcome. For example, the pulse frequency can be adjusted.
Further, a treatment system can include sensor locations outside of the tibial nerve at the ankle. For example EMG signals from the gluteus maximus (i.e., the buttocks), the perineum, or other locations will help to establish the baseline. These remote sensors can communicate directly with patch 100, or indirectly via the smart controller, using wireless communication methods such as Bluetooth. Further, the data from individual users can be transmitted to the cloud via a wirelessly connected smart controller or smartphone and in the cloud Al based analytics can be used to establish baseline parameters and determine deviations from the baseline.
In general, when patch 100 is applied to the skin and then uses sensors to detect when to stimulate, or how to adjust the stimulation, it uses sensing circuits that are separate from the circuits used for electrical stimulation. When the detection mechanism involves electrical signal sensing, the sensors use electrodes on the skin-facing surface of the patch. The controller monitors certain conditions through electrical signal sensing, then turns electrical stimulation on or off according to the treatment regime associated with the sensed condition. For example, muscle twitching may be detected by EMG. Patches use separate sensing electrodes and stimulation electrodes since each as different requirements.
However, separate sensing and stimulating electrodes increases the size of the patch and may require accurate placement of the patch. In contrast, in some examples, patch 100 uses the same set of electrodes for sensing as for stimulating. The connections to the controller are shared between sensing and stimulating functions, or the connection to each electrode is routed to unique controller pins with a low-impedance switch. The state of the switch is controlled by the controller, multiplexing sensing and stimulating functions.
Sensing requires a relatively high-impedance path from the skin surface to the analog-to-digital converter (“ADC”) circuit. The ADC may be a discrete component, passing a digital signal on to the controller, or the ADC may be integrated in the controller on one or more pins. High-impedance is required to generate a voltage proportional to the biometric, such as in EMG, the voltage having a range large enough to discriminate a wide set of values when digitized.
Stimulation requires a relatively low-impedance path to the skin surface, such that the driving circuit can overcome the impedance and drive energy into the tissue for treatment.
The two competing requirements may be combined through the use of a low-impedance or matched-impedance switch. The switch routes the signal captured at the electrode to either the sensing pin or the driving pin. For example, a single pin on the controller may be programmable to low- or high-impedance, and be able to both sense and drive into its load.
In another example, a small part of a larger stimulating electrode may be electrically isolated in the layout such that the small part may work as a sensing electrode when connected to the sensing circuit, and yet may work as part of the overall stimulating electrode when connected to the stimulating circuit. The isolation may be through two switches, one with low impedance for the sensing function, the other with impedance matching the overall impedance of the larger electrode. This latter aspect helps to minimize reflections and aberrations in the stimulating waveform when the stimulating circuit drives both the larger electrode area and the connected smaller area.
In another example, a patch uses a set of small electrodes to stimulate the skin. The overall impedance of the stimulating patches in combination is low, to optimize the effectiveness of the stimulation. The impedance of each individual small electrode is higher, such that it is effectively used in a sensing circuit.
In operation, patch 100 selects one or more of positive electrodes 1512, connecting each to stimulation voltage circuit 1520 with the corresponding stimulation switch 1530. The stimulation voltage passes from stimulation voltage circuit 1520 to all of the selected positive electrodes 1512, then as a field to negative electrodes 1514, and back to stimulation voltage circuit 1520. In example inventions, patch 100 selects the subset of the available positive electrodes 1512 to optimize the stimulation of the underlying tissue. The selection is adjusted in the software or firmware of processor 1516 according to the positioning of patch 100 on or near the target area.
Further, in example inventions, patch 100 selects the one or more sensor electrodes 1540 by activating sensing mode switch 1542 to connect the sensor to processor 1516. Processor 1516 uses one or more of hardware or software or firmware to analyze the measurement procured from sensor electrode 1540, using the analyzed measurement to inform the selection of positive electrodes 1512. Patch 100 changes the mode of sensing mode switch 1542 to connect sensor electrode 1540, or to return current wire 1534 when the electrode is used during a stimulation.
Data Manager
In examples, patch 100 includes a data manager implemented by control unit/processor 1002, which has primary responsibility for the storage and movement of data to and from the communications controller, sensors, actuators, and a master control program. The data manager has the capability to analyze and correlate any of the data under its control. It provides logic to select and activate nerves. Examples of such operations upon the data include: statistical analysis and trend identification; machine learning algorithms; signature analysis and pattern recognition, correlations among the data within a data warehouse, a therapy library, tissue models, electrode placement models, and other operations. There are several components to the data that is under its control as disclosed below.
The data warehouse is where incoming data is stored; examples of this data can be real-time measurements from the sensors, data streams from the Internet, or control and instructional data from various sources. The data manager will analyze data that is held in the data warehouse and cause actions, including the export of data, under master control program control. Certain decision making processes implemented by the data manager will identify data patterns both in time, frequency, and spatial domains and store them as signatures for reference by other programs. Techniques such as EMG, or multi-electrode EMG, gather a large amount of data that is the sum of hundreds to thousands of individual motor units and the typical procedure is to perform complex decomposition analysis on the total signal to attempt to tease out individual motor units and their behavior. The data manager will perform big data analysis over the total signal and recognize patterns that relate to specific actions or even individual nerves or motor units. This analysis can be performed over data gathered in time from an individual, or over a population of patch users.
The therapy library contains various control regimens for patch 100. Regimens specify the parameters and patterns of pulses to be applied by patch 100. The width and amplitude of individual pulses may be specified to stimulate nerve axons of a particular size selectively without stimulating nerve axons of other sizes. The frequency of pulses applied may be specified to modulate some reflexes selectively without modulating other reflexes. There are preset regimens that may be loaded from the cloud or 3rd party apps. The regimens may be static read-only as well as adaptive with read-write capabilities so they can be modified in real-time responding to control signals or feedback signals or software updates. One such example of a regimen has parameters A=40 volts, t=500 microseconds, T=1 Millisecond, n=100 pulses per group, and f=20 per second, repeated continuously for approximately 20 minutes. Other examples of regimens will vary the parameters within ranges previously specified.
The tissue models are specific to the electrical properties of particular body locations where patch 100 may be placed. Electric fields for production of action potentials will be affected by the different electrical properties of the various tissues that they encounter. The tissue models are combined with regimens from the therapy library and the electrode placement models to produce desired actions. MRI, ultrasound or other imaging or measurement of tissue of a body or particular part of a body may develop tissue models. This may be accomplished for a particular user and/or based upon a body norm. One such example of a desired action is the use of a tissue model together with a particular electrode placement model to determine how to focus the electric field from electrodes on the surface of the body on a specific deep location corresponding to the nerve in order to stimulate the nerve selectively to reduce incontinence of urine, or to treat constipation and FI. Other examples of desired actions may occur when a tissue model in combination with regimens from the therapy library and electrode placement models produce an electric field that stimulates targeted nerves.
Electrode placement models specify electrode configurations that patch 100 may apply and activate in particular locations of the body. For example, patch 100 may have multiple electrodes and the electrode placement model specifies where these electrodes should be placed on the body and which of these electrodes should be active in order to stimulate a specific structure selectively without stimulating other structures, or to focus an electric field on a deep structure. An example of an electrode configuration is a 4 by 4 set of electrodes within a larger array of multiple electrodes, such as an 8 by 8 array. This 4 by 4 set of electrodes may be specified anywhere within the larger array such as the upper right corner of the 8 by 8 array. Other examples of electrode configurations may be circular electrodes that may even include concentric circular electrodes. Patch 100 may contain a wide range of multiple electrodes of which the electrode placement models will specify which subset will be activated. Electrode placement models complement the regimens in the therapy library and the tissue models and are used together with these other data components to control the electric fields and their interactions with nerves, muscles, tissues and other organs. Other examples may include patch 100 having merely one or two electrodes, such as but not limited to those utilizing a closed circuit.
Stack-Up of the Patch
Electrodes 1620 are covered with a polyimide tape A 1624 to prevent short circuits from electrodes 1620 to PCBA 1630 and to prevent movement of electrodes 1630 within the layers of the assembly. Each electrode 1630 is coated on the skin-facing surface with hydrogel 1626. Each electrode 1620 has a release layer covering hydrogel 1626. A battery clip 1632 is attached to PCBA 1630. A battery 1636 is inserted into battery clip 1632. A battery pull-tab 1638 is inserted into battery clip 1632. PCBA 1630 is wrapped in polyimide tape B 1634 to restrict access by the user to the electronics. A top layer 1640 of fabric tape with adhesive on the PCBA-facing side is stacked on top to complete the assembly. Ankle bone cutouts 1642 are designed into the shapes of bottom layer 1610 and top layer 1640 to accommodate the ankle bone and to assist the user to correctly place patch 100.
Hydrogel Adaptation
Variations in the viscosity and composition of hydrogel 1626 leads to variation in the migration of the substance from its original area on each electrode to a wider area, possibly touching the skin outside the dimensions of patch 100. As the hydrogel migrates, its electrical performance changes. The circuitry on PCBA 1630 measures the voltage applied to the skin in real-time during the course of each treatment. The adaptive circuit calculates the charge delivered to the skin, which is a function of many parameters, including the conductivity of hydrogel 1626. Therefore, the performance of patch 100 is maintained while the hydrogel portion of the device changes its performance. The adaptive circuit adjusts the delivery of charge to also account for all changes in body and skin conductivity, perspiration and patch contact.
As the performance of the hydrogel 1626 decreases with time, the adaptive circuit and the firmware in PCBA 1630 records the expected life of the specific patch while it is powered on and on the skin of the user. When patch 100 determines that the device's lifetime is near an end, the firmware signals to the fob or smart controller, such that the user receives an indication that this patch has reached its limit.
Crimped Connection from Electrode to PCBA
Each electrode 1620 is coated with hydrogel 1626 when the electrode is manufactured. In some examples, soldering, when electrodes 1620 are manufactured, connects a wire 1622 to both the electrode and the PCBA 1630 in a permanent fashion. The electrode-plus-wire-plus-PCBA assemblies are each enclosed in an airtight bag until they are subsequently assembled with the tapes and adhesive layers to form a complete patch 100. Due to the complex nature of these assembly steps, the hydrogel on the electrodes may be exposed to air and humidity for a period of time, which affects the life expectancy of the hydrogel.
In an example, electrodes 1620 are coated with hydrogel 1626 but no wire is attached at that stage. Instead, a small clip is soldered to each electrode which does not affect the hydrogel nor attach the electrode to any larger assembly which would require longer time in the assembly line. These coated electrodes are each encased in an airtight bag with a heat seal or other means. The hydrogel does not degrade during the time that the coated electrode is inside the sealed bag.
In an example, wire 1622 is inserted into the small clip which had previously been soldered to electrode 1620, this connection being stronger and less prone to defect than the soldering or attachment of the wire strands directly to electrode 1620. The clip and the wire do not affect hydrogel 1626. Each coated electrode 1620, with its clip and attached wire, is encased in an airtight bag with a heat seal or other means. Hydrogel 1626 does not degrade during the time that the coated electrode is inside the sealed bag. The coated electrodes 1620 are removed from their airtight bags only immediately before they are connected to PCBA 1630.
An additional benefit of separating the coated electrodes 1620 from PCBA 1630 as two different subassemblies until put into a completed patch 100 is that coated electrodes found to be defective or expired from too lengthy time on the shelf may be discarded without the expense of discarding an already-attached PCBA. The more expensive PCBAs have a shelf life independent of the shelf life of the coated electrodes. These two subassemblies' inventories may be stocked, inspected and managed independently. This reduces the overall cost of manufacture of patches 100 devices without affecting their performance.
Die Cut Fabric Tape
In some examples, bottom layer 1610 is placed as a layer over electrodes 1620 using a solid layer of fabric tape. The overall thickness of patch 100 is therefore partly determined by the thickness of the fabric tape over electrodes 1620. Further, in order to place electrodes 1620 on the layer of fabric tape securely, the paper cover on the fabric tape must be pulled back to expose the adhesive coating. This results in a degradation of the adhesive properties of the tape.
In examples of patch 100, bottom layer 1610 fabric tape is cut to create holes 1612 for each of electrodes 1620, according to the defined sizes of those components. Each electrode 1620 is placed in the corresponding hole, without the added thickness of a fabric tape layer on top. Since no paper cover needs to be pulled back to mount electrodes 1620 to the fabric tape, the adhesive of the fabric tape is not affected. The holes may be cut with a die in order to create accurate edges, without tears or fibers, which may interfere with electrodes 1620.
Contoured to Ankle Bone
In some examples, patch 100 has a rectangular shape. This allows PCBA 1630, battery 1636 and electrodes 1620 to fit in between fabric and adhesive bottom layer 1610 and top layer 1640, and to be affixed to the skin by the user, then to be peeled away and discarded after use. In some examples, patch 100 has a shape contoured to the position in which it is to be affixed to the skin. The reference point in properly positioning patch 100 is the malleolus, or ankle bone in some example uses. Therefore, patch 100 has an ankle bone cutout 1642 along the vertical side, this cutout accommodating the ankle bone when patch 100 is placed close alongside the ankle bone.
In some examples, cutout 1642 is designed into patch 100 on only one side, such that battery 1636, PCBA 1630 and electrodes 1620 are properly aligned on one of the left or the right ankle. Patch 100 can then be offered in two varieties—one for the left ankle with cutout 1642 on the first vertical side, and one for the right ankle with cutout 1642 on the second vertical side.
In some examples, cutout 1642 is designed into patch 100 on both vertical sides, such that battery 1636, PCBA 1630 and electrodes 1620 are properly aligned on either of the left or right ankle. Patch 100 can then be offered in only one variety.
Battery and Battery Tab
Patch 100 includes battery 1636, which is enclosed by battery clip 1632, assembled onto PCBA 1630. During manufacturing, battery 1636 is inserted into battery clip 1632 to secure it from dropping out. In addition to the battery itself, battery pull tab 1638 is placed between one contact of battery 1636 and the corresponding contact in battery clip 1632. Battery pull tab 1638 prevents electrical connection between battery 1636 and battery clip 1632 at that contact until battery pull tab 1638 is removed. When in place, there is an open circuit such that patch 100 is not activated and does not consume power until battery pull-tab 1638 is removed.
In some examples, battery pull-tab 1638 is designed to be removed by pulling it out in the direction opposite that in which battery 1636 was inserted into battery clip 1632. This pulling action may lead to movement of the battery itself since it experiences a pulling force toward the open side of battery clip 1632. This battery movement may cause patch 100 to cease operating or to never activate.
In one example, battery pull-tab 1638 and battery clip 1632 are designed so that battery pull tab 1638 is pulled out in the same direction as battery 1636 was pushed into battery clip 1632. Therefore, the force pulling battery pull-tab 1638 out of patch 100 serves only to make battery 1636 more secure in its battery clip 1632. This reduces the chance of inadvertent movement of battery 1636 and the effect on activation or operation of patch 100.
Electrode Release Film
Each of electrodes 1620 in the assembled patch 100 is covered with a Polyethylene Terephthalate (“PET”) silicon covered release film 1626. The release film is pulled away by the user when patch 100 is affixed to the skin. In some examples, the PET silicon covered release film 1626 is transparent. This may lead to instances of confusion on the part of the user when the user may not be able to determine if the tape has been removed or not. Affixing patch 100 to the skin with any of electrodes 1620 still covered with tape will cause patch 100 to be ineffective. This ineffectiveness may not be noticed until the first treatment with patch 100. If the affixed patch 100 is found to be ineffective when the user is feeling an urge to urinate, the user may struggle to either properly void their bladder or to remove patch 100, peel off the tapes from the electrodes or affix a new patch 100 and suppress the urge with the re-affixed or new device.
In examples, PET silicon covered release film 1626 covering electrodes 1620 is selected in a color conspicuous to the user, such that the user will readily determine if the tape has been removed or not.
Examples use circuitry and firmware to stimulate the electrode circuit with a brief, low energy pulse or pulse sequence when patch 100 is initially activated. If patch 100 is activated before it is affixed to the skin, the electrode readiness test will fail. In such a case, the electrode readiness test is repeated, again and again according to timers in the firmware or hardware, until either the timers have all expired or the test passes. The test passes when patch 100 is found to exhibit a circuit performance appropriate to its design. The test fails when patch 100 is not properly prepared, such as not removing the electrode films, or is not yet applied to the skin when the timers have all expired. When the electrode readiness test fails, patch 100 signals to the fob or the smart controller, which in turn informs the user. The electrode readiness test is implemented in a manner which may be undetectable by the user, and to minimize the test's use of battery power.
Removable Paper
In some examples, a removable paper 1614 covers the adhesive side of bottom layer 1610. Removable paper 1614 may be in multiple sections, each to be pulled away by the user when affixing patch 100 to the skin. These removable papers may be in addition to the piece of PET film 1626 covering each electrode 1620. Therefore, the user must remove all of these pieces to expose a complete, adhesive surface to affix to the skin in examples.
In examples, bottom layer 1610 is one complete piece, with one removable paper 1614. The user removes all of the removable paper in one motion. In examples, bottom layer 1610 is two or more pieces, with two or more removable papers 1614. The user removes all of the removable papers. In examples, the single removable paper 1614 is designed with a pull-tab, so that the user pulls the removable paper off of the bottom layer in a direction at right angle to the long axis of patch 100. This motion reduces the forces experienced by the assembled internal components of patch 100.
In examples, removable paper 1614 covers bottom layer 1610 and covers all of the PET film sections 1626. An adhesive attaches the removable paper top surface to the polyimide tape A skin-facing surface, such that the user pulls the removable paper away from the bottom layer and in one motion removes the PET film pieces from electrodes 1620.
Patch 100 can also be made more comfortable by the addition of material between the top layer and the bottom layer, such as cushioning material that can cushion the electrodes and electronic components. The cushioning material may be disposed subjacent to the bottom layer and superjacent to the top layer, in at least a portion of patch 100. A cushioning material may include cellulosic fibers (e.g., wood pulp fibers), other natural fibers, synthetic fibers, woven or nonwoven sheets, scrim netting or other stabilizing structures, superabsorbent material, foams, binder materials, or the like, as well as combinations thereof.
Hydrogel Overlaps Electrode Edges
In some examples, each electrode 1620 is covered with hydrogel 1626, which conforms to the size of the electrode 1620, such that the edge of electrode 1620 is exposed to the user's skin when patch 100 is applied to the skin. This edge may abrade or cut the user's skin during the time when patch 100 is affixed to the skin.
In some examples, hydrogel 1626 is dimensioned so as to overlap the edges of electrode 1620. Hydrogel 1626 is placed over electrode 1620 with the accuracies of placement used in manufacturing, such that the edges of electrode 1620 is always covered with hydrogel 1626. This keeps the edge electrode 1620 from touching the user's skin. The risk of electrodes 1620 from abrading or cutting the user's skin is therefore eliminated.
Several examples are specifically illustrated and/or described herein. However, it will be appreciated that modifications and variations of the disclosed examples are covered by the above teachings and within the purview of the appended claims without departing from the spirit and intended scope of the invention.
This application claims priority to U.S. Provisional Patent Application Ser. No. 62/976,615, filed on Feb. 14, 2020, the disclosure of which is hereby incorporated by reference.
| Number | Date | Country | |
|---|---|---|---|
| 62976615 | Feb 2020 | US |
