Conductive GEL deployment chemical engine for wearable cardiac therapy devices

Abstract

Disclosed is a therapy electrode system comprising a chemical engine including a first chamber containing at least one chemical substance, a first working gas release aperture defined in a wall of the first chamber, a second chamber coupled to the first chamber, and a chemical substance arrest material disposed within the second chamber and configured to prevent the chemical substance from passing out of the chemical engine, and a chemical reaction initiator configured to initiate generation of a working gas by causing a chemical reaction involving the first chemical substance, and initiate release of the working gas out of the first chamber through the first working gas release aperture, and a conductive gel receptacle in fluid communication with the first working gas release aperture of the chemical engine configured to contain conductive gel to be released onto a body of a patient prior to delivering electrical therapy to the patient.

Description

Docket No. Z2011-7092WG(Z20877WO-01)CONDUCTIVE GEL DEPLOYMENT CHEMICAL ENGINE FOR WEARABLE CARDIAC THERAPY DEVICESCROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority under 35 U.S.C. § 119(e) to U.S. Provisional Patent Application Serial No. 63 / 748,759, titled “CONDUCTIVE GEL DEPLOYMENT CHEMICAL ENGINE FOR WEARABLE CARDIAC THERAPY DEVICES,” filed January 23, 2025, the entire content of which is incorporated herein by reference for all purposes.BACKGROUND

[0001] The present disclosure is generally directed to systems and methods of delivering electrical therapy to a patient.

[0002] There are a wide variety of electronic and mechanical devices for monitoring and treating patients’ medical conditions. In some examples, depending on the underlying medical condition being monitored or treated, medical devices such as cardiac monitors or defibrillators may be surgically implanted or externally connected to the patient. In some examples, physicians may use medical devices alone or in combination with drug therapies to treat conditions such as cardiac arrhythmias.

[0003] One of the deadliest cardiac arrhythmias is ventricular fibrillation, which occurs when normal, regular electrical impulses are replaced by irregular and rapid impulses, causing the heart muscle to stop normal contractions and to begin to quiver. Normal blood flow ceases, and organ damage or death can result in minutes if normal heart contractions are not restored. Because the victim has no perceptible warning of the impending fibrillation, death often occurs before the necessary medical assistance can arrive. Other cardiac arrhythmias can include excessively slow heart rates known as bradycardia or excessively fast heart rates known as tachycardia. Cardiac arrest can occur when a patient in which various arrhythmias of the heart, such as ventricular fibrillation, ventricular tachycardia, pulseless electrical activity (PEA), and asystole (e.g., the heart stops all electrical activity) result in the heart providing insufficient levels of blood flow to the brain and other vital organs for the support of life.

[0004] Cardiac arrest and other cardiac health ailments are a major cause of death worldwide. Various resuscitation efforts aim to maintain the body’s circulatory and respiratory systems during cardiac arrest in an attempt to save the life of the patient. The sooner these resuscitation efforts begin, the better the patient’s chances of survival.Docket No. Z2011-7092WO(Z20877WO-01)Implantable cardioverter / defibrillators (ICDs) or external defibrillators (such as manual defibrillators or automated external defibrillators (AEDs)) have significantly improved the ability to treat these otherwise life-threatening conditions. Such devices operate by applying corrective electrical pulses directly to the patient’s heart. Ventricular fibrillation or ventricular tachycardia can be treated by an implanted or external defibrillator, for example, by providing a therapeutic shock to the heart in an attempt to restore normal rhythm. To treat conditions such as bradycardia, an implanted or external pacing device can provide pacing stimuli to the patient’s heart until intrinsic cardiac electrical activity returns.

[0005] Some examples of cardiac monitoring and / or treatment devices include therapy electrodes that release conductive gel onto the skin of a patient prior to delivering electrical therapy to the patient to decrease electrical resistance between the therapy electrode and the patient.SUMMARY

[0006] In accordance with one aspect, there is provided a therapy electrode system for use in delivering electrical therapy. The system comprises a conductive gel deployment chemical engine comprising a first chamber configured to contain at least one chemical substance, a first working gas release aperture defined in a wall of the first chamber, a second chamber coupled to the first chamber, and a chemical substance arrest material configured to be disposed within the second chamber, the chemical substance arrest material configured to retain the at least one chemical substance thereby preventing the at least one chemical substance from passing out of the chemical engine, and a chemical reaction initiator configured to initiate generation of a working gas by causing a chemical reaction involving the at least one chemical substance, and initiate release of the working gas out of the first chamber through the first working gas release aperture while the at least one chemical substance is being retained within the chemical engine, and a conductive gel receptacle in fluid communication with the first working gas release aperture of the chemical engine, the conductive gel receptacle configured to contain conductive gel to be released onto a body of a patient prior to delivering the electrical therapy to the patient, and to release the conductive gel responsive to the release of the working gas.

[0007] In some embodiments, the system further comprises a rupturable seal obstructing the first working gas release aperture that is configured to rupture responsive to pressure applied to the rupturable seal by the working gas.Docket No. Z2011-7092WO(Z20877WO-01)

[0008] In some embodiments, the at least one chemical substance comprises a liquid and the chemical substance arrest material is configured to absorb the at least one chemical substance.

[0009] In some embodiments, the at least one chemical substance comprises a solid and the chemical substance arrest material includes a filter configured to retain the at least one chemical substance.

[0010] In some embodiments, the filter is a particle filter.

[0011] In some embodiments, the filter is a membrane filter.

[0012] In some embodiments, the at least one chemical substance has a non-neutral pH and the chemical substance arrest material includes a neutralization agent configured to neutralize the pH of at least one chemical substance.

[0013] In some embodiments, the first chamber comprises a first compartment and a second compartment, the first compartment configured to contain the at least one chemical substance, the second compartment configured to contain at least a second chemical substance configured to cause the chemical reaction responsive to contacting the at least one chemical substance.

[0014] In some embodiments, the chemical reaction initiator is configured to cause the at least one chemical substance and the second chemical substance to come into contact with one another and generate the working gas.

[0015] In some embodiments, the chemical reaction initiator comprises a plunger configured to push the at least one chemical substance from the first compartment into the second compartment.

[0016] In some embodiments, at least one of the at least one chemical substance or the second chemical substance is a liquid, and the chemical reaction initiator comprises a syringe configured to releasably house the at least one of the at least one chemical substance or the second chemical substance.

[0017] In some embodiments, the chemical reaction initiator includes a screw pump.

[0018] In some embodiments, the chemical reaction initiator is thermally actuated.

[0019] In some embodiments, the chemical reaction initiator is mechanically actuated.

[0020] In some embodiments, the chemical reaction initiator is electrically actuated.

[0021] In some embodiments, the chemical reaction initiator is magnetically actuated.

[0022] In some embodiments, the system further comprises a rupturable barrier between the first compartment and second compartment configured to separate the at least oneDocket No. Z2011-7092WO(Z20877WO-01)chemical substance from the second chemical substance prior to an action taken by the chemical reaction initiator.

[0023] In some embodiments, the chemical reaction initiator is configured to break the rupturable barrier by applying pressure to one of the at least one chemical substance or the second chemical substance.

[0024] In some embodiments, the chemical reaction initiator is configured to break the rupturable barrier by an action performed directly on the rupturable barrier.

[0025] In some embodiments, the action performed directly on the rupturable barrier includes mechanically breaking the rupturable barrier.

[0026] In some embodiments, the action performed directly on the rupturable barrier includes melting a portion of the rupturable barrier.

[0027] In some embodiments, the system further comprises a barrier removably disposed between the first compartment and the second compartment, the chemical reaction initiator configured to displace the barrier from between the first compartment and the second compartment thereby providing for the at least one chemical substance and the second chemical substance to come into contact with one another and generate the working gas.

[0028] In some embodiments, a second working gas release aperture is defined in a wall of the second chamber, the conductive gel receptacle being in fluid communication with the second working gas release aperture, the chemical engine configured to cause the generated working gas to pass through both the first working gas release aperture and the second working gas release aperture.

[0029] In some embodiments, the second chamber at least partially surrounds the first chamber.

[0030] In accordance with another aspect, there is provided a therapy electrode system for use in delivering electrical therapy. The system comprises a chemical engine comprising a first chamber configured to contain at least two chemical substances, a first working gas release aperture defined in a wall of the first chamber, a second chamber coupled to the first chamber, and a chemical substance arrest material configured to be disposed within the second chamber and to prevent the at least two chemical substances from passing out of the chemical engine, and a chemical reaction initiator configured to initiate generation of a working gas by causing a chemical reaction involving the at least two chemical substances, the first chamber configured to guide the generated working gas through the first working gas release aperture while the at least two chemical substances are retained within the chemical engine, and a conductive gel receptacle in fluid communication with the first working gasDocket No. Z2011-7092WO(Z20877WO-01)release aperture of the chemical engine, the conductive gel receptacle configured to contain conductive gel to be released onto a body of a patient prior to delivering the electrical therapy to the patient, and to release the conductive gel responsive to the release of the working gas.

[0031] In some embodiments, the at least two chemical substances are retained within the chemical engine at least in part by the chemical substance arrest material.

[0032] In some embodiments, the generated working gas is guided by the arrangement of the second chamber while the at least two chemical substances are retained within the chemical engine by the relative arrangement of the first working gas release aperture and the second chamber.

[0033] In some embodiments, the system further comprises a rupturable seal obstructing the first working gas release aperture that is configured to rupture responsive to pressure applied to the rupturable seal by the working gas.

[0034] In some embodiments, at least one of the at least two chemical substances comprises a liquid and the chemical substance arrest material is configured to absorb the at least one of the at least two chemical substances.

[0035] In some embodiments, the chemical substance arrest material includes a filter configured to retain at least one of the at least two chemical substances.

[0036] In some embodiments, the filter is a particle filter.

[0037] In some embodiments, the filter is a membrane filter.

[0038] In some embodiments, the filter is permeable to the working gas but impermeable to liquids.

[0039] In some embodiments, at least one of the at least two chemical substances has a non-neutral pH and the chemical substance arrest material includes a neutralization agent configured to neutralize the pH of the at least one of the at least two chemical substances.

[0040] In some embodiments, the first chamber includes a first compartment and a second compartment, the first compartment configured to contain a first of the at least two chemical substances, the second compartment configured to contain a second of the at least two chemical substances, the second of the at least two chemical substances configured to cause the chemical reaction responsive to contacting the first of the at least two chemical substances.

[0041] In some embodiments, the chemical reaction initiator is configured to cause the first of the at least two chemical substances and the second of the at least two chemical substances to come into contact with one another and generate the working gas.Docket No. Z2011-7092WO(Z20877WO-01)

[0042] In some embodiments, the chemical reaction initiator includes a plunger configured to push the first of the at least two chemical substances from the first compartment into the second compartment.

[0043] In some embodiments, at least one of the at least two chemical substances is a liquid, and the chemical reaction initiator includes a syringe configured to releasably house the at least one of the of the at least two chemical substances.

[0044] In some embodiments, the chemical reaction initiator includes a screw pump.

[0045] In some embodiments, the chemical reaction initiator is thermally actuated.

[0046] In some embodiments, the chemical reaction initiator is mechanically actuated.

[0047] In some embodiments, the chemical reaction initiator is electrically actuated.

[0048] In some embodiments, the chemical reaction initiator is magnetically actuated.

[0049] In some embodiments, the system further comprises a rupturable barrier between the first compartment and second compartment configured to separate the at least two chemical substances from one another prior to an action taken by the chemical reaction initiator.

[0050] In some embodiments, the chemical reaction initiator is configured to break the rupturable barrier by applying pressure to one of the at least two chemical substances.

[0051] In some embodiments, the chemical reaction initiator is configured to break the rupturable barrier by an action performed directly on the rupturable barrier.

[0052] In some embodiments, the action performed directly on the rupturable barrier includes mechanically breaking the rupturable barrier.

[0053] In some embodiments, the action performed directly on the rupturable barrier includes melting a portion of the rupturable barrier.

[0054] In some embodiments, the system further comprises a barrier removably disposed between the first compartment and the second compartment, the chemical reaction initiator configured to displace the barrier from between the first compartment and the second compartment thereby providing for the at least two chemical substances to come into contact with one another and generate the working gas

[0055] In some embodiments, a second working gas release aperture is defined in a wall of the second chamber, the conductive gel receptacle being in fluid communication with the second working gas release aperture, the chemical engine configured to cause the generated working gas to pass through both the first working gas release aperture and the second working gas release aperture.Docket No. Z2011-7092WO(Z20877WO-01)

[0056] In some embodiments, the second chamber at least partially surrounds the first chamber.

[0057] In some embodiments, the at least two chemical substances include at least three chemical substances.

[0058] In accordance with another aspect, there is provided a therapy electrode system for use in delivering electrical therapy. The system comprises a conductive gel deployment chemical engine comprising a first chamber configured to contain at least one chemical substance, a first working gas release aperture defined in a wall of the first chamber, a second chamber coupled to the first chamber, and a chemical substance arrest material configured to be disposed within the second chamber, the chemical substance arrest material configured to retain the at least one chemical substance thereby preventing the at least one chemical substance from passing out of the chemical engine, and an electric chemical reaction initiator configured to initiate generation of a working gas by applying an electric current to cause a chemical reaction involving the at least one chemical substance, and initiate release of the working gas out of the first chamber through the first working gas release aperture while the at least one chemical substance is being retained within the chemical engine, and a conductive gel receptacle in fluid communication with the first working gas release aperture of the chemical engine, the conductive gel receptacle configured to contain conductive gel to be released onto a body of a patient prior to delivering the electrical therapy to the patient, and to release the conductive gel responsive to the release of the working gas.

[0059] In some embodiments, the system further comprises a rupturable seal obstructing the first working gas release aperture that is configured to rupture responsive to pressure applied to the rupturable seal by the working gas.

[0060] In some embodiments, the at least one chemical substance comprises a liquid and the chemical substance arrest material is configured to absorb the at least one chemical substance.

[0061] In some embodiments, the at least one chemical substance comprises a solid and the chemical substance arrest material includes a filter configured to retain the at least one chemical substance.

[0062] In some embodiments, the first chamber comprises a first compartment and a second compartment, the first compartment configured to contain the at least one chemical substance, the second compartment configured to contain at least a second chemical substance configured to cause the chemical reaction responsive to contacting the at least one chemical substance.Docket No. Z2011-7092WO(Z20877WO-01)

[0063] In some embodiments, the electric chemical reaction initiator is configured to apply the electric current to cause the at least one chemical substance and the second chemical substance to come into contact with one another and generate the working gas.

[0064] In some embodiments, the electric chemical reaction initiator is configured to apply the electric current to produce heat in response to the electric current.

[0065] In some embodiments, the electric chemical reaction initiator is configured to apply the electric current to a heating element.

[0066] In some embodiments, the electric chemical reaction initiator is configured to apply the electric current to a resistive wire.

[0067] In some embodiments, the resistive wire comprises nickel chromium.

[0068] In some embodiments, the electric current is configured to heat the resistive wire to between 150°F and 230°F (66°C and 110°C), or between 230°F and 275°F (110°C and 135°C), or between 275°F and 800°F (135°C and 427°C).

[0069] In some embodiments, the system further comprises an isolating compartment configured to contain at least a second chemical substance, and wherein the resistive wire is configured to melt the isolating compartment or a portion of the isolating compartment thereby releasing the second chemical substance to come into contact with the at least one chemical substance and generate the working gas.

[0070] In some embodiments, the system further comprises a meltable membrane, and the resistive wire is configured to melt the meltable membrane thereby releasing the second chemical substance to come into contact with the at least one chemical substance and generate the working gas.

[0071] In some embodiments, the isolating compartment or a portion of the isolating compartment is configured to melt at a predetermined melting point.

[0072] In some embodiments, the predetermined melting point is between 150°F and 230°F (66°C and 110°C), or between 230°F and 275°F (110°C and 135°C), or between 275°F and 800°F (135°C and 427°C).

[0073] In some embodiments, the electric current is configured to heat the resistive wire to between 350°F and 450°F (177°C and 232°C).

[0074] In some embodiments, the working gas comprises a pressurized working gas released at between 1 to 10 psi (6.9 kPa to 69 kPa).

[0075] In some embodiments, the working gas comprises a pressurized working gas released at between 10 to 20 psi (69 kPa to 138 kPa).Docket No. Z2011-7092WO(Z20877WO-01)

[0076] In some embodiments, the working gas comprises a pressurized working gas released at between 5 to 100 psi (34.5 kPa to 689.5 kPa).

[0077] In some embodiments, the working gas comprises a pressurized working gas released at between 15 to 35 psi (103 kPa to 241 kPa).

[0078] In some embodiments, the chemical substance arrest material is configured to absorb one or both of the at least one chemical substance and the at least second chemical substance.

[0079] In some embodiments, the chemical substance arrest material comprises natural sponge, or synthetic sponge, or silica gel particles, or cotton material.

[0080] In some embodiments, the chemical substance arrest material comprises a particle filter.

[0081] In some embodiments, the chemical substance arrest material comprises a screen.

[0082] In some embodiments, the chemical substance arrest material comprises a membrane filter.

[0083] In some embodiments, the chemical substance arrest material comprises neutralization agent configured to neutralize the pH of one or both of the at least one chemical substance and the at least second chemical substance, or the reaction product of the chemical reaction.

[0084] In accordance with another aspect, there is provided a therapy electrode system for use in delivering electrical therapy. The system comprises a conductive gel deployment chemical engine comprising a first chamber configured to contain at least one chemical substance, a first working gas release aperture defined in a wall of the first chamber, a second chamber coupled to the first chamber, and a chemical substance arrest material configured to be disposed within the second chamber, the chemical substance arrest material configured to retain the at least one chemical substance thereby preventing the at least one chemical substance from passing out of the chemical engine, and a mechanical chemical reaction initiator configured to initiate generation of a working gas by mechanically actuating the chemical engine to cause a chemical reaction involving the at least one chemical substance, and initiate release of the working gas out of the first chamber through the first working gas release aperture while the at least one chemical substance is being retained within the chemical engine, and a conductive gel receptacle in fluid communication with the first working gas release aperture of the chemical engine, the conductive gel receptacle configured to contain conductive gel to be released onto a body of a patient prior to delivering theDocket No. Z2011-7092WO(Z20877WO-01)electrical therapy to the patient, and to release the conductive gel responsive to the release of the working gas.

[0085] In some embodiments, the system further comprises a rupturable seal obstructing the first working gas release aperture that is configured to rupture responsive to pressure applied to the rupturable seal by the working gas.

[0086] In some embodiments, the at least one chemical substance comprises a liquid and the chemical substance arrest material is configured to absorb the at least one chemical substance.

[0087] In some embodiments, the at least one chemical substance comprises a solid and the chemical substance arrest material includes a filter configured to retain the at least one chemical substance.

[0088] In some embodiments, the first chamber comprises a first compartment and a second compartment, the first compartment configured to contain the at least one chemical substance, the second compartment configured to contain at least a second chemical substance configured to cause the chemical reaction responsive to contacting the at least one chemical substance.

[0089] In some embodiments, the system further comprises a rupturable barrier between the first compartment and second compartment, and the mechanical chemical reaction initiator is configured to mechanically actuate the chemical engine by breaking the rupturable barrier.

[0090] In some embodiments, the mechanical chemical reaction initiator is configured to break the rupturable barrier by applying pressure to one of the at least one chemical substance or the second chemical substance.

[0091] In some embodiments, the mechanical chemical reaction initiator is configured to break the rupturable barrier by an action performed directly on the rupturable barrier.

[0092] In some embodiments, the working gas comprises a pressurized working gas released at between 5 to 100 psi (34.5 kPa to 689.5 kPa).

[0093] In some embodiments, the working gas comprises a pressurized working gas released at between 15 to 35 psi (103 kPa to 241 kPa).

[0094] In some embodiments, the chemical substance arrest material is configured to absorb one or both of the at least one chemical substance and the at least second chemical substance.

[0095] In some embodiments, the chemical substance arrest material comprises natural sponge, or synthetic sponge, or silica gel particles, or cotton material.Docket No. Z2011-7092WG(Z20877WO-01)

[0096] In some embodiments, the chemical substance arrest material comprises a particle filter.

[0097] In some embodiments, the chemical substance arrest material comprises a screen.

[0098] In some embodiments, the chemical substance arrest material comprises a membrane filter.

[0099] In some embodiments, the chemical substance arrest material comprises neutralization agent configured to neutralize the pH of one or both of the at least one chemical substance and the at least second chemical substance, or the reaction product of the chemical reaction.

[0100] In some embodiments, the mechanical chemical reaction initiator comprises a plunger configured to push the at least one chemical substance from the first compartment into the second compartment.

[0101] In some embodiments, at least one of the at least one chemical substance or the second chemical substance is a liquid, and the mechanical chemical reaction initiator comprises a syringe configured to releasably house the at least one of the at least one chemical substance or the second chemical substance.

[0102] In some embodiments, the mechanical chemical reaction initiator includes a screw pump.BRIEF DESCRIPTION OF THE DRAWINGS

[0103] Various aspects of at least one example are discussed below with reference to the accompanying figures, which are not intended to be drawn to scale. The figures are included to provide an illustration and a further understanding of the various aspects and examples, and are incorporated in and constitute a part of this specification, but are not intended to limit the scope of the disclosure. The drawings, together with the remainder of the specification, serve to explain principles and operations of the described and claimed aspects and examples. In the figures, each identical or nearly identical component that is illustrated in various figures is represented by a like numeral. For purposes of clarity, not every component may be labeled in every figure.

[0104] FIG. 1 depicts a wearable medical device, in accordance with an example of the present disclosure;

[0105] FIG. 2 depicts a plan view of a therapy electrode that can be used with the wearable medical device of FIG. 1;Docket No. Z2011-7092WG(Z20877WO-01)

[0106] FIG. 3 depicts an example of a conductive gel deployment chemical engine in accordance with the present disclosure that uses a chemical reaction to produce a pressurized gas that may be provided to therapy electrodes as disclosed herein to cause the release of conductive gel;

[0107] FIG. 4 depicts another example of a chemical engine in accordance with the present disclosure that uses a chemical reaction to produce a pressurized gas that may be provided to therapy electrodes as disclosed herein to cause the release of conductive gel;

[0108] FIG. 5 depicts another example of a chemical engine in accordance with the present disclosure that uses a chemical reaction to produce a pressurized gas that may be provided to therapy electrodes as disclosed herein to cause the release of conductive gel;

[0109] FIG. 6 depicts another example of a chemical engine in accordance with the present disclosure that uses a chemical reaction to produce a pressurized gas that may be provided to therapy electrodes as disclosed herein to cause the release of conductive gel;

[0110] FIG. 7 depicts another example of a chemical engine in accordance with the present disclosure that uses a chemical reaction to produce a pressurized gas that may be provided to therapy electrodes as disclosed herein to cause the release of conductive gel;

[0111] FIG. 8 depicts another example of a chemical engine in accordance with the present disclosure that uses a chemical reaction to produce a pressurized gas that may be provided to therapy electrodes as disclosed herein to cause the release of conductive gel;

[0112] FIG. 9 depicts another example of a chemical engine in accordance with the present disclosure that uses a chemical reaction to produce a pressurized gas that may be provided to therapy electrodes as disclosed herein to cause the release of conductive gel;

[0113] FIG. 10A depicts another example of a chemical engine in accordance with the present disclosure that uses a chemical reaction to produce a pressurized gas that may be provided to therapy electrodes as disclosed herein to cause the release of conductive gel;

[0114] FIG. 10B depicts another example of a chemical engine in accordance with the present disclosure that uses a chemical reaction to produce a pressurized gas that may be provided to therapy electrodes as disclosed herein to cause the release of conductive gel;

[0115] FIG. 10C depicts another example of a chemical engine in accordance with the present disclosure that uses a chemical reaction to produce a pressurized gas that may be provided to therapy electrodes as disclosed herein to cause the release of conductive gel;

[0116] FIG. 11 A depicts another example of a chemical engine in accordance with the present disclosure that uses a chemical reaction to produce a pressurized gas that may be provided to therapy electrodes as disclosed herein to cause the release of conductive gel;Docket No. Z2011-7092WG(Z20877WO-01)

[0117] FIG. 1 IB depicts another example of a chemical engine in accordance with the present disclosure that uses a chemical reaction to produce a pressurized gas that may be provided to therapy electrodes as disclosed herein to cause the release of conductive gel; and

[0118] FIG. 12 depicts another example of a chemical engine in accordance with the present disclosure that uses a chemical reaction to produce a pressurized gas that may be provided to therapy electrodes as disclosed herein to cause the release of conductive gel.DETAILED DESCRIPTION

[0119] The particulars shown herein are by way of example and for purposes of illustrative discussion of the various aspects and embodiments disclosed herein only and are presented in the cause of providing what is believed to be the most useful and readily understood description of the principles and conceptual aspects of the disclosure.

[0120] The aspects and embodiments disclosed herein will now be described by reference to more detailed embodiments. The aspects and embodiments disclosed herein may, however, be embodied in different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the aspects and embodiments disclosed herein to those skilled in the art.

[0121] As used in the description of the aspects and embodiments disclosed herein and the appended claims, the singular forms “a,” “an,” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise.

[0122] Unless otherwise indicated, all numbers expressing quantities of ingredients, reaction conditions, and so forth used in the specification and claims are to be understood as being modified in all instances by the term “about.” Accordingly, unless indicated to the contrary, the numerical parameters set forth in the following specification and attached claims are approximations that may vary depending upon the desired properties sought to be obtained by the present invention. At the very least, and not as an attempt to limit the application of the doctrine of equivalents to the scope of the claims, each numerical parameter should be construed in light of the number of significant digits and ordinary rounding approaches.

[0123] As used herein, the term “about” or “approximately” when referring to a measurable value such as an amount, a pressure, and the like, is meant to encompass variations of + / — 10%, more preferably + / -5%, even more preferably, + / -!%, and still moreDocket No. Z2011-7092WO(Z20877WO-01)preferably + / — 0.1% from the specified value, as such variations are appropriate to perform the disclosed methods.

[0124] Notwithstanding that the numerical ranges and parameters setting forth the broad scope of the aspects and embodiments disclosed herein are approximations, the numerical values set forth in the specific examples are reported as precisely as possible. Any numerical value, however, inherently contains certain errors necessarily resulting from the standard deviation found in their respective testing measurements. Every numerical range given throughout this specification will include every narrower numerical range that falls within such broader numerical range, as if such narrower numerical ranges were all expressly written herein.

[0125] Additional advantages of the aspects and embodiments disclosed herein will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the aspects and embodiments disclosed herein. It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the aspects and embodiments disclosed herein, as claimed.

[0126] This disclosure relates to improvements to pressure sources including a conductive gel deployment chemical engine for facilitating release and distribution of conductive gel for use with, for example, a cardiac electrotherapeutic device such as a wearable defibrillator or a wearable cardioverter defibrillator. In some examples, the cardiac electrotherapeutic device includes functionality for providing cardioversion, defibrillation, and / or pacing electric pulses to a patient in the event of one or more cardiac arrhythmias. Prior to such electrotherapies, in some implementations, aspects and embodiments of the devices disclosed herein are configured to deliver conductive gel to the interface of the therapy electrode and the patient’ s skin. In implementations, aspects and embodiments of the devices disclosed herein include a controller for implementing a therapy protocol as described herein. The controller is configured to initiate the delivery of the conductive gel, e.g., by sending signals to a chemical engine to initiate a chemical reaction to generate working gas for causing the delivery of the conductive gel. As will be defined in detail below, various designs can be used for a pressure source for causing the delivery of such conductive gel. In examples below, the pressure source designs can include various alternatives for creating or causing the release of a pressurized working gas to effect upon or actuate the deployment of the conductive gel to the interface of the therapy electrode and the patient’s skin. Upon creation or release of theDocket No. Z2011-7092WO(Z20877WO-01)pressurized working gas, the pressurized working gas facilitates deployment of, for example, the conductive gel prior to delivery of a therapeutic shock to a patient.

[0127] During operation, and prior to administering a therapeutic shock, one or more components of a wearable defibrillator can facilitate release of a conductive gel. For example, the wearable defibrillator can include a gel deployment device, e.g., a gel deployment chemical engine, configured to release a quantity of conductive gel between a therapy electrode and a patient’s skin. The conductive gel can be stored within one or more gel reservoirs in the gel deployment device until released. To release the conductive gel, the gel deployment device can include one or more pressure sources configured to generate or release a pressurized working gas. The pressurized working gas can be directed such that the pressurized working gas mechanically pushes the conductive gel out of the gel reservoirs. Various conductive gel deployment chemical engine devices, configurations and implementations are described herein in greater detail.

[0128] In one or more examples, the gel deployment chemical engines as described herein can be configured to produce or release a pressurized working gas at a predetermined pressure configured to cause release of the conductive gel from the conductive gel reservoirs. For example, a pressure source can be configured to create or release a pressurized working gas having a pressure of approximately 1 psi to 10 psi (6.9 kPa to 69 kPa) (for example, greater than 1 psi (6.9 kPa), greater than 5 psi (34.5 kPa), greater than 8 psi (55 kPa)) to facilitate conductive gel release. For example, a pressure source can be configured to create or release a pressurized working gas having a pressure of approximately 10 psi to 20 psi (69 kPa to 138 kPa) (for example, greater than 10 psi (69 kPa), greater than 15 psi (103 kPa), or greater than 18 psi (124 kPa)) to facilitate conductive gel release. For example, a pressure source can be configured to create or release a pressurized working gas having a pressure of approximately 15 psi to 40 psi (103 kPa to 276 kPa) (for example, greater than 15 psi (103 kPa), greater than 20 psi (138 kPa), greater than 25 psi (172 kPa), greater than 30 psi (207 kPa), or greater than 35 psi (241 kPa)) to facilitate conductive gel release. In some implementations, the gel deployment chemical engines can be configured to produce or release a pressurized working gas at about 35 psi (241 kPa). In other examples, the gel deployment chemical engines can be configured such that they release a pressurized working gas that is configured to fill a certain cavity or space to a specific pressure. In certain implementations, the gel deployment chemical engines can be configured to release a pressurized working gas such that a cavity or other open space is pressurized to a pressure of about 15 psi to 40 psi (103 kPa to 276 kPa). In some configurations, the gel deploymentDocket No. Z2011-7092WO(Z20877WO-01)chemical engines can be configured to release a pressurized working gas such that a cavity or other open space is pressurized to a pressure of about 35 psi (241 kPa). Though the following description related to levels of pressure produced by the pressure sources (e.g., in pounds per square inch or kPa), it should be appreciated that the functioning of the gel deployment chemical engines as detailed herein can be described by way of exerted force as well.

[0129] It should be noted that the above described gel deployment chemical engines are examples, and additional details are provided in the following discussions of the figures.

[0130] As described below in additional detail, various gel deployment chemical engine configurations can be used for a pressure source. In some examples, the pressure source is configured to facilitate a chemical reaction therein. As a result of the chemical reaction, an amount of pressurized working gas such as carbon dioxide gas is produced and directed to, for example, a plurality of conductive gel reservoirs for facilitating release of the conductive gel stored therein. More generally, the gel deployment chemical engine or engines described herein may generate, as a result of the chemical reaction, an amount of pressurized working gas for one or more conductive gel reservoirs, which may be distributed over one or more therapy electrodes. Chemical engines as described herein include pressure sources utilizing chemical reactions to generate a pressurized working gas. For example, an electrically actuated chemical engine includes an electrical chemical reaction initiator configured to initiate a chemical reaction by applying an electric current. For example, a mechanically actuated chemical engine includes a mechanical chemical reaction initiator configured to initiate a chemical reaction by mechanically causing two chemicals to come in contact with one another to cause the reaction. As an implementation, as described in further detail below, a chemical can be housed in a syringe and on actuation the syringe releases the chemical to physically come in contact with a second, other chemical to initiate a chemical reaction. In examples, a mechanically actuated chemical engine includes a mechanical chemical reaction initiator configured to initiate a chemical reaction by mechanically breaking, rupturing, removing, or compromising a barrier separating two chemicals so that such chemicals come in contact with one another to cause the reaction.

[0131] The pressurized working gas can include any non-noxious gas, such as carbon dioxide, carbon monoxide, nitrogen, oxygen, nitric oxide, nitrogen dioxide, nitrous oxide, hydrogen, fluorine, chlorine, helium, neon, argon, krypton, xenon, radon, or mixtures of two or more thereof. In some implementations, the pressurized working gas includes carbon dioxide, nitrogen, oxygen, nitrogen dioxide, hydrogen, helium, neon, argon, krypton, xenon,Docket No. Z2011-7092WG(Z20877WO-01)radon, or mixtures of two or more thereof. In some implementations, the pressurized working gas includes carbon dioxide, nitrogen, oxygen, or mixtures of two or more thereof.

[0132] FIG. 1 illustrates an example of a medical device 100 that is external, ambulatory, and wearable by a patient 102, and configured to implement one or more configurations described herein. For example, the medical device 100 can be a non-invasive medical device configured to be located substantially external to the patient. Such a medical device 100 can be, for example, an ambulatory medical device that is capable of and designed for moving with the patient as the patient goes about his or her daily routine. For example, the medical device 100 can be bodily-attached to the patient, e.g., via a garment configured to be worn about the torso of the patient. Such wearable defibrillators can be prescribed to be worn nearly continuously or substantially continuously for, e.g., two or more weeks, a month, or two to three months at a time. During the period of time in which they are worn by the patient, the wearable defibrillator can be configured to continuously or substantially continuously monitor the vital signs of the patient and, upon determination that treatment is warranted, can be configured to deliver one or more therapeutic electrical pulses to the patient. For example, such therapeutic shocks can be pacing, defibrillation, or transcutaneous electrical nerve stimulation (TENS) pulses. As noted above, the wearable cardiac device described herein is configured for continuous use by the patient. In scenarios, such continuous use can be substantially or nearly continuous in nature. That is, the wearable medical device can be continuously used, except for sporadic periods during which the use temporarily ceases (e.g., while the patient bathes, while the patient is refit with a new and / or a different garment, while the battery is charged / changed, while the garment is laundered, etc.). Such substantially or nearly continuous use as described herein may nonetheless be considered continuous use. For example, the wearable medical device can be configured to be worn by a patient for as many as 24 hours a day. In some implementations, the patient can remove the wearable medical device for a short portion of the day (e.g., for half an hour to bathe). In such an example, nearly continuous can include 23.5 hours a day of wear with a half hour removal period.

[0133] Further, the wearable medical device can be configured as a long term or extended use medical device. Such devices can be configured to be used by the patient for an extended period of several days, weeks, months, or even years. In some examples, the wearable medical device can be used by a patient for an extended period of at least one week. In some examples, the wearable medical device can be used by a patient for an extended period of at least 30 days. In some examples, the wearable medical device can be used by a patient for anDocket No. Z2011-7092WG(Z20877WO-01)extended period of at least one month. In some examples, the wearable medical device can be used by a patient for an extended period of at least two months. In some examples, the wearable medical device can be used by a patient for an extended period of at least three months. In some examples, the wearable medical device can be used by a patient for an extended period of at least six months. In some examples, the wearable medical device can be used by a patient for an extended period of at least one year. In some implementations, the extended use can be uninterrupted until a physician or other healthcare provider (HCP) provides specific instruction to the patient to stop use of the wearable medical device.

[0134] Regardless of the extended period of wear, the use of the wearable medical device can include continuous wear by the patient as described above. For example, the continuous use can include continuous wear or attachment of the wearable medical device to the patient, e.g., through one or more of the electrodes as described herein, during both periods of monitoring and periods when the device may not be monitoring the patient but is otherwise still worn by or otherwise attached to the patient. The wearable medical device can be configured to continuously monitor the patient for cardiac -related information (e.g., ECG information, including arrhythmia information, cardio-vibrations, etc.) and / or non-cardiac information (e.g., blood oxygen, the patient’s temperature, glucose levels, tissue fluid levels, and / or lung vibrations). The wearable medical device can carry out its monitoring in periodic or aperiodic time intervals or times. For example, the monitoring during intervals or times can be triggered by a user action or another event.

[0135] As noted above, the wearable medical device can be configured to monitor other non-ECG physiologic parameters of the patient in addition to cardiac related parameters. For example, the wearable medical device can be configured to monitor, for example, pulmonary-vibrations (e.g., using microphones and / or accelerometers), breath vibrations, sleep related parameters (e.g., snoring, sleep apnea), tissue fluids (e.g., using radio-frequency transmitters and sensors), among others.

[0136] The medical device 100 can include one or more of the following: a garment 110, one or more sensing electrodes 112 (e.g., ECG electrodes), one or more therapy electrodes 114, a medical device controller 120, a connection pod 130, a patient interface pod 140, a belt, or any combination of these. In some examples, at least some of the components of the wearable medical device 100 can be configured to be affixed to the garment 110 (or in some examples, permanently integrated into the garment 110), which can be worn about the patient’s torso. The medical device 100 in combination with the therapy electrode system described herein may comprise an aspect of the disclosure.Docket No. Z2011-7092WG(Z20877WO-01)

[0137] The controller 120 can be operatively coupled to the sensing electrodes 112, which can be affixed to the garment 110, e.g., assembled into the garment 110 or removably attached to the garment, e.g., using hook and loop fasteners. In some implementations, the sensing electrodes 112 can be permanently integrated into the garment 110 (or removably attached to the garment). The controller 120 can be operatively coupled to the therapy electrodes 114. For example, the therapy electrodes 114 can also be assembled into the garment 110, or, in some implementations, the therapy electrodes 114 can be permanently integrated into the garment 110. Additionally, the therapy electrodes 114 can include one or more conductive gel deployment devices. The controller 120 is operatively connected to the chemical engine associated with the one or more conductive gel deployment devices.

[0138] Component configurations other than those shown in FIG. 1 are possible. For example, the sensing electrodes 112 can be configured to be attached at various positions about the body of the patient 102. The sensing electrodes 112 can be operatively coupled to the medical device controller 120, such as through the connection pod 130 if present. In some implementations, the sensing electrodes 112 can be adhesively attached to the patient 102. In some implementations, the sensing electrodes 112 and therapy electrodes 114 can be included on a single integrated patch and adhesively applied to the patient's body.

[0139] The sensing electrodes 112 can be configured to detect one or more cardiac signals. Examples of such signals include ECG signals, heart sounds, and / or other sensed cardiac physiological signals from the patient. The sensing electrodes 112 can also be configured to detect other types of patient physiological parameters, such as tissue fluid levels, lung sounds, respiration sounds, patient movement, etc. In some examples, the therapy electrodes 114 can also be configured to include sensors configured to detect ECG signals as well as other physiological signals of the patient. The connection pod 130 can, in some examples, include a signal processor configured to amplify, filter, and digitize these cardiac signals prior to transmitting the cardiac signals to the controller 120. One or more therapy electrodes 114 can be configured to deliver one or more therapeutic defibrillating shocks to the body of the patient 102 when the medical device 100 determines that such treatment is warranted based on the signals detected by the sensing electrodes 112 and processed by the controller 120.

[0140] FIG. 2 is a plan view of a therapy electrode portion of a therapy electrode assembly that includes a conductive gel deployment chemical engine and that can be used with a wearable medical device, such as the wearable defibrillator described above with respect to FIG. 1. The gel deployment chemical engine, when activated, can dispense anDocket No. Z2011-7092WG(Z20877WO-01)electrically conductive gel onto the exposed surface of the electrode portion of the therapy electrode assembly that, in use, is placed most proximate to the patient’s body. For example, the chemical engine includes a chemical reaction initiator configured to initiate generation of a working gas and / or initiate release of the working gas to cause the release of the conductive gel.

[0141] As shown in FIG. 2, the therapy electrode 200 can be a multiple layer laminated structure that includes an electrically conductive layer (disposed on the bottom surface of the therapy electrode 200). In use, the electrically conductive layer can be disposed substantially adjacent to the patient’s skin, although the conductive layer need not make direct contact with the patient, as portions of the garment 110 (as shown in FIG. 1) and / or portions of the patient’s clothing can be present between the electrically conductive layer and the patient’s skin. In some implementations, the garment 110 can include a pocket or other similar structure including a mesh material (e.g., a porous material, such as a porous material with pores large enough to allow conductive gel to pass through) that can be configured to act as an interface between the electrically conductive layer and the patient’s skin. In an example, the mesh material can include a knotted fabric having a silver coating to enable a conductive path between the surface of the therapy electrode and the patient’s skin. In this regard, upon deployment of the conductive gel, the mesh material provides electrical pathways between the electrically conductive layer and the patient’s skin.

[0142] As shown in FIG. 2, various components of the gel deployment device can be disposed on a side of the therapy electrode 200 (e.g., the top side shown in FIG. 2) that is opposite the side on which the conductive layer is formed.

[0143] The therapy electrode 200 can include a plurality of conductive gel reservoirs 210, each of which has a respective gel delivery outlet 220. Each of the gel reservoirs can be fluidly coupled to a fluid channel 230 and a pressure source 240. Each of the gel reservoirs 210 may be fluidly coupled to the pressure source 240 by a common fluid channel 230 or individual fluid channels or fluid channels that serve a group of gel reservoirs 210. The pressure source 240 can be fluidly coupled to the fluid channel 230 and, when activated by an activation signal, can release a pressurized working gas, such as compressed gas, into the channel 230. The hydraulic pressure of the working gas from the activated pressure source 240 in the fluid channel 230 can force the conductive gel stored in each of the plurality of gel reservoirs 210 out of the plurality of gel delivery outlets 220 through apertures formed in the electrically conductive layer and onto the exposed surface of the electrically conductive layer that, in use, is placed most proximate to the patient’s body. The apertures in the electricallyDocket No. Z2011-7092WG(Z20877WO-01)conductive layer can be substantially aligned with the plurality of gel delivery outlets 220 so that when activated, the electrically conductive gel can be dispensed onto the exposed surface of the electrode portion that is disposed most proximate to the patient’s body.

[0144] As noted above, a conductive gel deployment chemical engine can be configured to facilitate a chemical reaction. For example, the controller 120 is operatively connected to the chemical engine, e.g., the chemical reaction initiator of the chemical engine. The controller 120 can transmit signals to the chemical engine based on the operational details regarding the therapy protocol as described herein. As a result of the chemical reaction, an amount of pressurized working gas can be produced and directed to, for example, one or more or a plurality of conductive gel reservoirs in a therapy electrode 200 as described above for facilitating release of the conductive gel stored therein. Thus, in some examples, the pressure source 240 may be provided by a conductive gel deployment chemical engine.

[0145] The pressurized working gas can include any non-noxious gas. Examples are discussed above.

[0146] FIGS. 3 and 4 illustrate various example configurations for a chemical engine that incorporates a chemical reaction to produce a pressurized working gas. The chemical engines can include a chamber design that allows for the storage and timely mixing of two or more chemicals to produce the pressurized working gas. For example, such timely mixing of the two of more chemicals to produce the pressurized working gas occurs in the context of the timing of electrotherapy delivery to the ambulatory patient. For instance, when an arrhythmia is sensed in the patient via the ECG sensing electrodes and corresponding arrhythmia detection analysis executed by controller 120, the wearable medical device is configured to provide an alert to the patient via a user interface. The patient is provided a predetermined duration of time to respond to the alert to indicate to the wearable medical device that the patient is conscious and that treatment should be delayed and / or canceled. For example, depending on the underlying arrhythmia the response time may be configured to be within a range from 15 seconds to 90 seconds. In some examples, the arrhythmia detection analysis executed by controller 120 can be configured to categorize the heart rate as below a predetermined ventricular tachycardia (VT) threshold, above the VT threshold but below a ventricular fibrillation (VF) threshold, or above the VF threshold. If the controller 120 identifies VF, there is a response time of 25 seconds (e.g., as an example default value, but, in examples, programmable up to 55 seconds, up to 75 seconds, or up to 90 seconds) to allow the patient time to respond to the alerts. The lower threshold for VF identification can be set from 120 to 250 beats per minute (bpm), with a default of 200 bpm. If the controllerDocket No. Z2011-7092WO(Z20877WO-01)identifies VT, there is a response time of 60 seconds (e.g., as an example default value, but, in examples, programmable up to 90 seconds, up to 120 seconds, up to 150 seconds, up to 180 seconds, or up to 210 seconds, or up to 240 seconds). The lower threshold for VT identification can be set from 120 to the VF threshold, with a default setting of 150 bpm.

[0147] In some examples, if the patient does not respond in the durations described above, the controller 120 is configured to send a gel deployment electronic signal via one or more cables to the gel deployment chemical engine. For example, such electronic signal can be sent to therapy control circuitry implemented within the connection pod 130, if present, or elsewhere. Such therapy control circuitry in the connection pod 130 can receive the gel deployment electronic signal from the controller 120 and, in turn, generate and transmit the chemical engine triggering signal to initiate a chemical reaction in the chemical engine. For example, such chemical engine triggering signal can be an electrical triggering signal in a range from between 1 pA and 1A of current for between 1 ms and 2 minutes, e.g., around 10 pA to around 1 mA for around 1 ms to around 1 minute, e.g., 100 pA to around 10 mA for around 10 ms to around 30 seconds. For example, the resistance of the wire disposed between the therapy control circuitry and the chemical engine can be in a range of 1 milliOhm to around 10 Ohm, e.g., 1 Ohm to around 5 Ohm.

[0148] For example, the chemical reaction can include mixing two chemicals (or more than two chemicals) together to produce a chemical reaction, resulting in the creation of a pressurized working gas. The chemical reaction can include, for example, mixing two or more fluids together, mixing one or more fluids with one or more solids, or mixing two or more solids together. Aspects and embodiments of chemical engines as disclosed herein can include a chamber design that allows for the storage and timely mixing of two or more chemicals to produce the pressurized working gas. For example, the chemical reaction can include mixing two chemical substances together to produce a chemical reaction, resulting in the creation of a pressurized working gas. In examples, the chemical engine as described herein is configured to operate in temperature ranges from around 0°C to around 60°C, and be stored at temperatures ranging from around -35°C to around 80°C, at around 0% to 98% relative humidity.

[0149] In this regard, the chamber design is configured to comply with such requirements and facilitate operation as described in such conditions. In some examples, the chemical engine implementations described herein can operate and be stored in altitudes of up to 10,000 - 20,000 feet (3.05 km - 6.10 km). In example implementations, the chemical reactions as described herein are configured to operate in temperature ranges from aroundDocket No. Z2011-7092WO(Z20877WO-01)0°C to around 60°C. In some examples, the chemical engine implementations described herein can operate and be stored at altitudes of up to 10,000 - 20,000 feet (3.05 km - 6.10 km).

[0150] In certain implementations, the chemical reaction can include mixing an acid with a base to produce a pressurized working gas, for example, pressurized carbon dioxide gas. The resulting carbon dioxide gas can be directed by the chemical engine through a working gas release aperture of the chemical engine and into, for example, a fluid channel 230 of a therapy electrode 200 as described above. The carbon dioxide gas can apply pressure, e.g., hydraulic pressure to the individual gel reservoirs 210 of the therapy electrode 200, thereby facilitating release of conductive gel stored within the conductive gel reservoirs.

[0151] Depending upon the operating conditions of the chemical engine, a certain pressure level of the pressurized working gas can be configured to, for example, facilitate conductive gel release in a conductive gel deployment device. For example, the pressure level of the pressurized working gas can be configured based upon the internal volume of the fluid channel (as well as any additional spaces the pressurized working gas is configured to fill, such as air gaps or spaces in the gel reservoirs). The pressure level can also be configured based upon an applied pressure level for releasing the conductive gel from the gel reservoirs. In certain implementations, the gel reservoirs can include a frangible seal configured to release the conductive gel at a predetermined pressure, such as an applied pressure of about 15 psi (103 kPa). This applied pressure, in combination with the internal volume the pressurized working gas is configured to fill, can be used to determine a total overall pressure level for the pressurized working gas. For example, the combined internal volume the pressurized working gas is configured to fill can be approximately 25 cubic centimeters. In other examples, the internal volume the pressurized working gas is configured to fill can be approximately 5-50 cm3. In other examples, the internal volume can change as the conductive gel is released (i.e., to account for the space in the gel reservoirs previously occupied by the conductive gel). As such, in certain implementations, the initial internal volume can be approximately 5-10 cm3and the final internal volume can be approximately 10-50 cm3.

[0152] In some implementations, the chemical engines utilizing chemical reactions as described below can be configured to produce or release a pressurized working gas at approximately 1 to 10 psi (6.9 to 69 kPa), 10 to 20 psi (69 kPa to 138 kPa), or 20 to 100 psi (138 kPa to 689 kPa). In some implementations, the chemical engines utilizing chemical reactions as described below can be configured to produce or release a pressurized working gas at approximately 15 psi to 40 psi (103 kPa to 276 kPa). In some examples, the chemicalDocket No. Z2011-7092WG(Z20877WO-01)engines utilizing chemical reactions can be configured to produce or release a pressurized working gas at about 35 psi (241 kPa), or at a similar pressure to fill the internal volume (such as a one or more fluid conduits used in a gel deployment device as described above) to a pressure of about 35 psi (241 kPa).

[0153] In certain implementations, the chemical reaction can include applying an acidic solution to a reactive metal.

[0154] Additionally, while the following discussions are generally directed to chemical reactions, physical reactions can be included as well. For example, a nucleation process can be used to produce an amount of pressurized working gas.

[0155] In some implementations, a liquid including a suspended gas (such as a carbonated liquid including suspended carbon dioxide) can be mixed with a solid including a surface covered with microscopic features such as peaks and valleys. When the solid is introduced to the liquid, the suspended gas attaches to the microscopic features, forming bubbles around all the features. Once the amount of forming bubbles exceeds the amount of gas the liquid can stably suspend, excess gas can be released from the liquid as a pressurized working gas. As above, this pressurized working gas can be directed to the gel reservoirs of a therapy electrode for facilitation of the conductive gel release.

[0156] Specific examples of chemical engines utilizing chemical reactions to generate a pressurized working gas are described below in additional detail.

[0157] FIG. 3 illustrates a chemical engine 300 configured to produce a pressurized working gas as, for example, a product of a chemical reaction. In operation, the chemical engine 300 can be integrated into a therapy electrode such as therapy electrode 200 as discussed above, e.g., replacing pressure source 240 as discussed in reference to therapy electrode 200. A controller, such as medical device controller 120, can be operably connected to the chemical engine 300. The medical device controller 120 can be configured to provide an electrical signal to the chemical engine 300 prior to delivery of, for example, a therapeutic shock to a patient. The electrical signal can be configured to facilitate or otherwise initiate a chemical reaction configured to produce a pressurized working gas. The pressurized working gas can then be directed through the fluid channel 230 to the conductive gel reservoirs 210 of the therapy electrode 200, thereby causing release of the conductive gel stored therein.

[0158] The pressurized working gas can include any non-noxious gas. Examples are discussed above.

[0159] The chemical engine 300 can include a chamber 302 configured to contain the chemicals and other components related to facilitating a chemical reaction. Depending uponDocket No. Z2011-7092WO(Z20877WO-01)the design of the chemical engine 300, and the types of chemical substances contained therein, various materials and methods of manufacture can be used to construct the chamber 302. For example, the chemical reaction used by the chemical engine 300 can be configured to produce approximately 35 psi (241 kPa). As such, the material used for the manufacture of chamber 302 can be selected and configured to withstand an applied pressure greater than 35 psi (241 kPa)plus some safety margin (e.g., an additional about 1-50 psi (6.9-345 kPa)). The chamber 302 can be made of plastic, metal, a metal alloy, ceramic, and / or a combination thereof. In certain implementations, the chamber 302 can be molded from a thermoplastic polymer and / or a thermoset polymer. In some examples, the chamber 302 can be shaped such that any pressurized working gas contained therein is directed in a particular direction. For example, the chamber 302 can be shaped like a cone having an opening or exit port at the point or narrow end, a tapering cylinder having an opening or exit port at the narrow end, a pyramid having an opening or exit port at one of the points, and other similar shapes that provide one or more geometric features for directed pressurized working gas flow.

[0160] In some implementations, the chamber 302 is made of a clear or transparent material to allow visual monitoring of the contents of the chamber.

[0161] The chamber 302 can be made of a thermoplastic material. For example, the thermoplastic material can be high density polyethylene, low density polyethylene, ultra high-molecular weight polyethylene, polypropylene, nylon, and / or polyethylene terephthalate. Alternatively, it is understood that any viable thermoplastic material may be used. The material may be transparent, opaque, or partially opaque.

[0162] Examples of thermoplastic polymers include polystyrene, polyetherketone, polyetheretherketone, polyetherketoneketone, polyethersulfone, polycarbonate, polyolefin such as polypropylene, polyethylene, or cyclic olefin, polyester such as polyethylene terephthalate or polyethylene naphthalate, polyamide (nylon), or other well-known materials in the plastics art. Amorphous plastics such as amorphous nylon exhibit high transparency and may also be suitable.

[0163] Thermoset resins include epoxy, epoxy novolac, phenolic, polyurethane, and polyimide.

[0164] In some implementations, the chamber 302 can be manufactured from a copolymer such as an ethylene acid copolymer through an injection molding or thermoforming process. For example, the chamber 302 can be manufactured from an ionomer resin of ethylene acid copolymer having a density of approximately 0.94 g / cm3. As such, the tensile strength of the ionomer resin can be configured based upon the thickness of theDocket No. Z2011-7092WO(Z20877WO-01)ionomer resin. An example of a commercially available ionomer resin of ethylene acid copolymer is Surlyn® resin, which is available from DuPont™.

[0165] The thickness of the walls of the chamber 302 can be configured such that the chamber 302 is configured to withstand an applied pressure of greater than, for example, about 100 psi (689.5 kPa). Thus, in some examples, irrespective of the material used, the thickness of the walls may be defined such that the chamber 302 (or of any other design) withstands the expected applied pressure. In certain implementations, the ionomer resin has a thickness of approximately 0.125 inches (0.32 cm) can withstand an applied pressure of approximately 250 psi (1724 kPa).

[0166] In certain implementations, a clear plastic such as polycarbonate or a composite plastic blend (e.g., an ethylene acid copolymer and polycarbonate blend) can be used to manufacture chamber 302 if, for example, the chamber 302 is to be subjected to visual inspection (e.g., to confirm that the chemical reaction has not occurred prior to installation of the pressure source). Depending upon the tensile strength of the blended materials, a thickness for the walls of the chamber 302 can be configured such that the chamber is configured to withstand the applied pressure as described above.

[0167] Additionally, in the present example or one or more other examples, the chamber 302 can be manufactured from a material having a relatively low water vapor transmission rate. The ionomer resin has a water vapor transmission rate of about 0.8 g / 100 in2 / day (0.8 g / 0.065 m2 / day). Using a material with a low permeability such as the ionomer resin can provide an advantage of a longer shelf-life of a chemical engine relative to conventional configurations as the rate of evaporation of any liquid chemicals through the ionomer resin is low.

[0168] In certain implementations, in the present example or one or more other examples, the chamber 302 can be manufactured from a plastic material using an injection molding process. In certain implementations, the chamber 302 can be manufactured from the ionomer resin in a design (e.g., having a specific geometry and wall thickness) capable of both housing enough chemicals as needed for the chemical reaction while still maintaining its structural integrity after the chemical reaction (e.g., the chamber 302 is configured to handle the pressure of the fluid produced as a result of the chemical reaction). In additional implementations, the chamber 302 can be formed by a thermoforming process, or other similar forming process.Docket No. Z2011-7092WO(Z20877WO-01)

[0169] The chamber 302 can also be made from a non-reactive metal such as stainless steel. The stainless steel can be stamped, rolled, or similarly formed to contain the chemical substances and other components related to facilitating the chemical reaction.

[0170] In certain implementations, the chamber 302 can be configured and formed such that it defines at least one working gas release aperture 304 for directing a pressurized working gas (produced by, for example, a chemical reaction within the chamber 302).Depending upon the design of the chemical engine 300, the working gas release aperture 304 can include a valve (e.g., a one-way flow valve) to prevent contamination or foreign chemicals from entering into the chamber 302. In certain implementations, the valve (whether a one-way flow valve or not) can be configured to open at a predetermined pressure (e.g., about 5 psi to 20 psi (34.5 kPa to 138 kPa)) to prevent chemicals from escaping the chamber 302 prior to the chemical reaction. In some examples, the valve can be configured to open at about 10 psi (69 kPa).

[0171] The chemical engine 300 can include a first chemical substance 306 and a second chemical substance 308. The first chemical substance 306 can be a solid base loaded into a first chamber 302 in, for example, a powder or compressed solid form. For example, the solid compressed form can be provided by compressing powdered ingredients. For example, the active chemical ingredient, the solid base in powder form, can be mixed with other inert agents such as fillers and binders to improve compressibility. Example binders and fillers include microcrystalline cellulose (MCC), a binder that compresses chemical ingredients into uniform compressed solid forms with consistent weight and hardness, dibasic calcium phosphate (DCP), a binder with good compressibility that can also be used as a filler to adjust the compressed solid weight, lactose, cellulose, methyl cellulose, polyvinyl pyrrolidine, gelatin, polyvinylpyrrolidone (PVP), hydroxypropyl methylcellulose (HPMC), polyethylene glycol (PEG), and / or starch. In examples, such compressed solids are formed by exerting pressure (e.g., in a range of around 50 to 400 megapascals, MPa) to compact either the active chemical alone or along with other inert agent materials. In examples, if a sufficiently homogenous mix of the components cannot be obtained through simple mixing, the ingredients can be granulated prior to compression to assure an even distribution of the active compound in the final compressed solid form. In examples, prior to pressing into the compressed solid form, granulated powders can be evenly distributed into a die cavity. Once the die cavity is filled with the chemical material, the upper and lower punches of a tablet press can compress the material within the die to form the compressed solid. In an example implementation, the first chamber 302 includes an isolating compartment 310. The secondDocket No. Z2011-7092WG(Z20877WO-01)chemical substance 308 can be contained in the isolating compartment 310. The isolating compartment 310 can be configured to act as a mechanical barrier positioned to provide isolation of the second chemical substance 308 from the first chemical substance 306 until the second chemical substance 308 is released or otherwise mixed with first chemical substance 306, thereby eliminating unwanted and / or untimely reactions. In examples, a chemical substance described herein may not be limited to a single chemical compound but may include two or more chemical compounds.

[0172] The second chemical substance 308 can be a liquid chemical such as an acid. The isolating compartment 310 can be filled with the second chemical substance prior to insertion into the chamber 302. In certain implementations, to facilitate ejection of the second chemical substance 308 from the isolating compartment 310, the second chemical substance 308 can be filled into the isolating compartment 310 such that it is stored in the isolating compartment 310 under pressure at, for example, 15 psi to 35 psi (103 kPa to 241 kPa).

[0173] In some examples, the second chemical substance 308 can be filled into the isolating compartment 310 at about 25 psi (172 kPa). Thus, when the isolating compartment 310 is compromised, the second chemical substance 308 is forcibly released from the isolating compartment 310. In certain implementations, a mechanical chemical reaction initiator includes an external pressure applying device such as a leaf spring or an elastic band that can apply an external pressure to the isolating compartment 310. For example, as shown in FIG. 3, a set of leaf springs 314 can be positioned adjacent to the isolating compartment 310 and be configured to apply an external pushing force against the isolating compartment 310. When the isolating compartment 310 is compromised, the leaf springs 314 can assist in the release of the second chemical substance 308 from the isolating compartment 310.

[0174] In some implementations, the first chemical substance 306 is a metal carbonate or bicarbonate and the second chemical substance 308 is an acid. When the metal carbonate or bicarbonate and the acid mix together, a reaction occurs to produce carbon dioxide, salt, and water.

[0175] The metal carbonate can be any metal carbonate. In some implementations, the metal carbonate is lithium carbonate, sodium carbonate, potassium carbonate, rubidium carbonate, cesium carbonate, beryllium carbonate, magnesium carbonate, calcium carbonate, strontium carbonate, barium carbonate, manganese carbonate, iron carbonate (siderite), cobalt carbonate, nickel carbonate, copper carbonate, zinc carbonate, silver carbonate, cadmium carbonate (otavite), aluminum carbonate, thallium carbonate, lead carbonate, ammonium carbonate, bismuth subcarbonate, lanthanum carbonate, uranyl carbonate, or mixtures thereof.Docket No. Z2011-7092WO(Z20877WO-01)In some implementations, the metal carbonate is sodium carbonate, potassium carbonate, magnesium carbonate, calcium carbonate, copper carbonate, zinc carbonate, ammonium carbonate, or mixtures thereof.

[0176] The metal bicarbonate can be any metal bicarbonate. In some implementations, the metal bicarbonate is lithium bicarbonate, sodium bicarbonate, potassium bicarbonate, cesium bicarbonate, magnesium bicarbonate, calcium bicarbonate, ammonium bicarbonate, or mixtures thereof. In some implementations, the metal bicarbonate is sodium bicarbonate, potassium bicarbonate, magnesium bicarbonate, calcium bicarbonate, ammonium bicarbonate, or mixtures thereof.

[0177] The acid can be any acid in a concentration such that it can react to produce carbon dioxide but can be safely stored in the chamber 302. The acid can be a mineral acid, sulfonic acid, carboxylic acid, halogenated carboxylic acid, or mixtures thereof. In some implementations, the acid is hydrofluoric acid, hydrochloric acid, hydrobromic acid, hydroiodic acid, hypochlorous acid, chlorous acid, chloric acid, perchloric acid, hypobromous acid, bromous acid, bromic acid, perbromic acid, hypoiodous acid, iodous acid, iodic acid, periodic acid, sulfuric acid, nitric acid, phosphoric acid, fluoro sulfuric acid, fluoroantimonic acid, fluoroboric acid, hexafluorophosphoric acid, chromic acid, methanesulfonic acid, ethanesulfonic acid, benzenesulfonic acid, p-toluenesulfonic acid, trifluoromethanesulfonic acid, polystyrene sulfonic acid, acetic acid, citric acid, formic acid, gluconic acid, lactic acid, oxalic acid, tartaric acid fluoroacetic acid, trifluoroacetic acid, chloroacetic acid, dichloroacetic acid, trichloroacetic acid, ascorbic acid, or mixtures thereof. In some implementations, the acid is hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, acetic acid, or mixtures thereof.

[0178] The concentration of the acid can be adjusted by adding a solvent such as water. In some implementations, the concentration of the acid is adjusted such that the pH of the acid is in the range of about 2 to less than 7. In some implementations, acids with a pH of less than 2 can be used in small quantities — e.g., less than 0.1 grams in a chamber having a volume of about 25 cm3.

[0179] For example, the reactants include sodium carbonate of a predetermined concentration and hydrochloric acid of a predetermined concentration. As noted, sodium carbonate can be of a predetermined concentration, including for example, a predetermined concentration in a range of 80%-90% concentration, 90%-95% concentration, or 95%-99% concentration. For example, sodium carbonate of a predetermined concentration in a range of 95%-99% concentration can be caused to react with hydrochloric acid of a predeterminedDocket No. Z2011-7092WO(Z20877WO-01)concentration. For example, hydrochloric acid can be of a predetermined concentration, including, for example, a predetermined concentration in a range of 0.1%- 1% concentration, l%-2% concentration, or 3%-8% concentration.

[0180] For example, the reactants include sodium bicarbonate of a predetermined concentration and citric acid of a predetermined concentration. As noted, sodium bicarbonate can be of a predetermined concentration, including for example, a predetermined concentration in a range of 80%-90% concentration, 90%-95% concentration, or 95%-99% concentration. For example, sodium bicarbonate of a predetermined concentration in a range of 95%-99% concentration can be caused to react with citric acid of a predetermined concentration. For example, citric acid can be of a predetermined concentration, including, for example, a predetermined concentration in a range of 1 %- 10% concentration, 10%-20% concentration, or 20%-50% concentration.

[0181] For example, the reactants can include hydrogen peroxide of a predetermined concentration and sodium hypochlorite of a predetermined concentration. As noted, hydrogen peroxide can be of a predetermined concentration, including for example, a predetermined concentration in a range of 0. l%-5% concentration, 5%-10% concentration, or 10%-20% concentration. For example, hydrogen peroxide of a predetermined concentration in a range of 5%- 10% concentration can be caused to react with sodium hypochlorite of a predetermined concentration. For example, sodium hypochlorite can be of a predetermined concentration, including, for example, a predetermined concentration in a range of l%-5% concentration, 10%-25% concentration, or 25-30% concentration.

[0182] A total volume of the reactants can be in a range from 0.5 cc to 20 cc. For example, a total volume of the reactants can be 0.5 cc. For example, a total volume of the reactants can be 2.0 cc. For example, a total volume of the reactants can be 5 cc. For example, a total volume of the reactants can be 10 cc. For example, a peak pressure of a chemical reaction can be in a range from around 1 psi to around 30 psi (around 6.9 kPa to around 207 kPa). For example, a peak pressure of the chemical reaction can be around 2 psi (13.8 kPa). For example, a peak pressure can be around 5 psi (34.5 kPa). For example, a peak pressure of the chemical reaction can be around 10 psi (69 kPa). For example, a peak pressure of the chemical reaction can be around 12 psi (83 kPa). For example, a peak pressure of the chemical reaction can be around 20 psi (138 kPa). For example, a peak pressure of the chemical reaction can be around 30 psi (207 kPa).Docket No. Z2011-7092WO(Z20877WO-01)

[0183] In some implementations, the chemical engine 300 can include a first chemical substance 306 and a second chemical substance 308, wherein the first chemical substance 306 and the second chemical substance 308 are selected to produce nitrogen gas or oxygen gas.

[0184] To produce oxygen gas, the first chemical substance 306 can be sodium chlorate, potassium perchlorate, potassium permanganate, potassium iodide, or mixtures thereof and the second chemical substance 308 can be hydrogen peroxide, barium peroxide, iron powder, or mixtures thereof. Yeast can be used as the first chemical substance 306 in some implementations. In some implementations, the second chemical substance 308 is hydrogen peroxide. In some implementations, the second chemical substance 308 is hydrogen peroxide and the first chemical substance 306 can be one or a mixture of potassium iodide, yeast, and potassium permanganate.

[0185] To produce nitrogen gas, the first chemical substance 306 can be an ammonium compound and the second chemical substance 308 can be a chemical substance that reacts with the ammonium compound to produce nitrogen gas. Examples of the ammonium compound include ammonium nitrite, ammonium nitrate, ammonium, chloride, ammonium dichromate, ammonium hydroxide, or mixtures thereof. Examples the second chemical substance 308 can be sodium nitrite, potassium nitrite, calcium nitrite, or other nitrite compound.

[0186] Nitrogen gas can also be produced by the reaction of hypochlorites or hypobromites on ammonia, reduction of nitric and / or nitrous oxides, reaction of ammonia gas with a nitrite compound, or combinations of these reactions.

[0187] It should be noted that the quantities provided of the first chemical substance 306 and the second chemical substance 308 can be varied depending upon the size and shape of the chamber 302 and the amount of pressure the chemical substance reaction is configured to produce. For example, to produce a higher pressure than, for example, the implementations as described above, additional quantities of the first chemical substance 306 and the second chemical substance 308 can be used in a similarly shaped chamber 302. In some implementations, more reactive chemicals can be used to produce a pressurized working gas having a higher pressure level.

[0188] The first chemical substance 306 can be added in an amount of about 0.001 grams to about 1000 grams. In some embodiments the first chemical substance 306 can be added in an amount of 0.001 to about 50 wt % of the total amount of the first chemical substance 306 and the second chemical substance 308. The second chemical substance 308 can be added in an amount of about 0.001 grams to about 1000 grams. In some embodiments the secondDocket No. Z2011-7092WG(Z20877WO-01)chemical substance 308 can be added in an amount of 0.001 to about 50 wt % of the total amount of the first chemical substance 306 and the second chemical substance 308.

[0189] In some embodiments, the first chemical substance 306 and the second chemical substance 308 are present in an amount sufficient to produce an amount of carbon dioxide, which produces a pressure of from about 5 psi to about 100 psi (from about 34.5 kPa to about 689 kPa). In some implementations, the pressure is from about 10 psi to about 70 psi (about 69 kPa to about 483 kPa). In some implementations, the pressure is from about 15 psi to about 50 psi (from about 103 kPa to about 345 kPa). In some implementations, the pressure is from about 15 psi to about 35 psi (from about 103 kPa to about 241 kPa).

[0190] In certain implementations, the isolating compartment 310 can be made from a membrane or another material that, in response to applied heat (e.g., via an electric source) or force, can be structurally compromised to release the second chemical substance 308 such that it mixes with the first chemical substance 306. In certain implementations, the isolating compartment 310 can be configured such that it is structurally compromised upon application of heat from one or more heat sources. For example, as shown in FIG. 3, an electric chemical reaction initiator includes a heating element such as resistive wire 312 that can be disposed proximate to, or in contact with the isolating compartment 310, e.g., wrapped around the isolating compartment 310 or otherwise pressed against a portion of the isolating compartment 310. In this implementation, the electric current when applied to the heating element produces heat in response to the applied current. The isolating compartment 310 or at least a portion of the isolating compartment 310 can be formed from a meltable membrane such as a thermoplastic configured to melt at a predetermined melting point. In certain implementations, the isolating compartment 310 or at least a portion of the isolating compartment 310 can be configured to have a melting point of approximately 150°F-230°F (65.6°C-110°C). In certain implementations, the isolating compartment 310 or at least a portion of the isolating compartment 310 can be configured to have a melting point of approximately 230°F-275°F (110°C-135°C). In certain implementations, the isolating compartment 310 or at least a portion of the isolating compartment 310 can be configured to have a melting point of approximately 275°F-800°F (135°C-427°C). In certain implementations, the isolating compartment 310 or at least a portion of the isolating compartment 310 can be manufactured from polyethylene having a melting point of approximately 230°F-275°F (110°C-135°C). In some examples, the isolating compartment 310 or at least a portion of the isolating compartment 310 can be manufactured from a material having a low evaporation permeability (e.g., a material having a low water vaporDocket No. Z2011-7092WO(Z20877WO-01)transmission rating) when compared to conventional thermoplastics. A material with a low evaporation permeability can provide the advantage of an extended shelf life of the pressure source as the second chemical substance 308 is less likely to evaporate or leak from the isolating compartment 310.

[0191] The resistive wire 312 can be constructed from a material that produces heat in response to an applied current. For example, the resistive wire 312 may be configured to produce (e.g., provide) heat at a temperature of between 150°F to 230°F (65.6°C-110°C) in response to the applied current. For example, the resistive wire 312 may be configured to produce heat at a temperature of between 230°F to 275°F (110°C to 135°C) in response to the applied current. For example, the resistive wire 312 may be configured to produce heat at a temperature of between 275°F to 800°F (135°C to 427°C) in response to the applied current. In some examples, the resistive wire 312 comprises nickel chromium, e.g., the resistive wire 312 can be made from nickel chromium wire. The thickness of the resistive wire 312 can be selected such that the temperature of the wire, when an appropriate current is applied, exceeds the melting point of the isolating compartment 310 or at least a portion of the isolating compartment 310. For example, a 20-gauge to a 28-gauge wire can be used, the wire configured to heat to approximately 350°F to 450°F (177°C to 232°C). In certain implementations, a 24-gauge nickel chromium wire having a 0.020-inch (0.05 cm) diameter can heat to 400°F (204°C) at relatively low amperages as compared to a similarly sized copper wire.

[0192] To facilitate mixing of the first chemical substance 306 and the second chemical substance 308, the electric chemical reaction initiator operates by applying an electric current to the resistive wire 312. For example, a controller can send a signal to the electric chemical reaction initiator to initiate generation of the working gas by applying the electric current. The resistive wire 312 can heat up past the melting point of the isolating compartment 310 or at least a portion of the isolating compartment 310, thereby causing a puncturing or rupturing of the isolating compartment 310 and release of the second chemical substance 308 (e.g., through the internal pressure of the second chemical substance 308 within the isolating compartment 310 as described above). The second chemical substance 308 can mix with the first chemical substance 306, thereby producing a pressurized working gas. A chemical reaction initiator includes the resistive wire 312 and associated current supply and is configured to initiate generation of a working gas by causing a chemical reaction involving the first chemical substance 306. In some examples, the chemical reaction initiator subsequently initiates release of the working gas out of the chamber 302 through the workingDocket No. Z2011-7092WO(Z20877WO-01)gas release aperture 304 or causes the at least one chemical substance, such as the first chemical substance 306, and the second chemical substance 308 to come into contact with one another to react and generate the working gas.

[0193] In this disclosure, various chemical reaction initiator systems, devices, apparatus, and / or mechanisms are provided to initiate, e.g., by causing a chemical reaction, the generation of a working gas, and to initiate release of the working fluid or gas from the chemical engine. In some examples, the initiator is an electrical chemical reaction initiator configured to be electrically actuated. In some examples, the initiator is a mechanical chemical reaction initiator configured to be mechanically actuated. In some examples, the initiator is a thermal chemical reaction initiator configured to be thermally actuated. In some examples, the initiator is a magnetic chemical reaction initiator configured to be magnetically actuated. In various configurations disclosure herein, the chemical reaction initiator includes systems, devices, apparatus, and / or mechanisms configured to simultaneously initiate or cause generation of a working fluid or gas from the chemical engine and release of such working fluid or gas from the chemical engine. In various configurations as disclosed herein, the chemical reaction initiator includes systems, devices, apparatus, and / or mechanisms configured to first initiate or cause generation of a working fluid or gas from the chemical engine and then, after the generation of the working fluid or gas, initiate release of such working fluid or gas from the chemical engine.

[0194] As such, in examples, a single system, device, apparatus, and / or mechanism can be provided to both initiate or cause the generation of the working fluid or gas and release such working fluid or gas from the chemical engine. For example, as described in detail below, a puncturing pin and associated actuation device is implemented to initiate or cause a chemical reaction by puncturing or otherwise compromising an isolating compartment housing a chemical thus allowing the chemical to come in contact with a second chemical. As a result, an underlying chemical reaction occurs to initiate or cause the generation of the working fluid or gas. The working gas in this case is automatically guided or directed towards to one or more gel reservoirs, thereby facilitating release of conductive gel stored in the gel reservoirs.

[0195] In some scenarios, a first system, device, apparatus, and / or mechanism can be provided to first initiate or cause the generation of the working fluid or gas and then, after the generation of the working fluid or gas, a second system, device, apparatus, and / or mechanism can be provided initiate release of such working fluid or gas from the chemical engine. For example, as described in detail below, a puncturing pin and associated actuation device isDocket No. Z2011-7092WG(Z20877WO-01)implemented to first initiate or cause a chemical reaction by puncturing or otherwise compromising an isolating compartment housing a chemical thus allowing the chemical to come in contact with a second chemical. As a result, an underlying chemical reaction occurs to initiate or cause the generation of the working fluid or gas. Then, a pressure valve configured to operate at a predetermined pressure or force level (as discussed in detail below) is configured to initiate release of such working fluid or gas from the chemical engine.

[0196] The shape of the chamber 302 can direct the pressurized working gas out of the working gas release aperture 304. The working gas release aperture 304 can be connected to a fluid channel in, for example, the therapy electrode 200 as described above in regard to FIG.2. The pressurized working gas can be directed through the fluid channel to one or more gel reservoirs, thereby facilitating release of conductive gel stored in the gel reservoirs.

[0197] In certain implementations, alternate release methods can be used to puncture or otherwise compromise the isolating compartment 310 and release the second chemical substance 308. For example, a puncturing pin and actuation device (such as a solenoid) can be used to puncture the isolating compartment 310. In certain implementations, the isolating compartment 310 can be configured as a syringe configured to eject a quantity of the second chemical substance 308 in response to, for example, a force pressing against a plunger of the syringe. In some examples, an alternative melting device can be used in place of the resistive wire 312. For example, a small laser can be configured to focus an emitted laser beam or pulse onto the isolating compartment 310 to melt a small portion of the isolating compartment 310.

[0198] Depending upon the resistance of the resistive wire 312, and desired timing for the release of the conductive gel, the medical device controller 120 can be configured to deliver an appropriate electrical signal (e.g., at a high enough current to heat the resistive wire 312) at the appropriate time (e.g., providing for adequate timing for the chemical reaction to occur and for the subsequent release of the conductive gel). In some examples, the chemical engine 300 can also include a localized power source that, in response to the signal from the medical device controller 120, is configured to provide a current to the resistive wire 312, thereby heating the resistive wire 312. A localized power source for powering, at least in part, the chemical reaction initiator may be provided in other examples, such as to actuate a solenoid for puncturing the isolating compartment 310 or to actuate the plunger among others.

[0199] As noted above, in operation, the chemical engine 300 can be integrated into a therapy electrode such as therapy electrode 200 as discussed above, e.g., replacing pressure source 240 as discussed in reference to therapy electrode 200. A controller, such as medicalDocket No. Z2011-7092WG(Z20877WO-01)device controller 120, can be operably connected to the chemical engine. The medical device controller 120 can be configured to provide an electrical signal to the chemical engine 300 prior to delivery of, for example, a therapeutic shock to a patient. The electrical signal can include a current to be directed to the resistive wire 312, thereby heating the resistive wire 312. Once heated, the resistive wire 312 can melt the isolating compartment 310, resulting in the release of the second chemical substance 308 from the isolating compartment 310. The second chemical substance 308 can mix with the first chemical substance 306, causing a chemical reaction. The chemical reaction can produce a pressurized working gas (e.g., pressurized carbon dioxide gas), which is directed through the working gas release aperture 304. The pressurized working gas can flow through the fluid channel 230 to each of the conductive gel reservoirs 210 of a therapy electrode. The pressurized working gas can cause release of the conductive gel contained within the conductive gel reservoirs 210, thereby resulting in the conductive gel flowing through the apertures in the electrically conductive layer of the therapy electrode that is substantially proximate the patient’s body. The medical device controller 120 can then facilitate delivery of the therapeutic shock.

[0200] It should be noted that the arrangement of components as shown in FIG. 3 is by way of example only. For example, the isolating compartment 310 is shown as positioned in the center of the chamber 302 for explanatory purposes only. In certain implementations, the isolating compartment 310 can be positioned against a wall of the chamber 302, at one end of the chamber 302, or at any location within the chamber 302 that still provides for adequate chemical mixing prior to the chemical reaction. Additionally, the chemical engine 300 is shown as having the second chemical substance 308 positioned inside the isolating compartment 310. In other designs, the first chemical substance 306 can be placed within the isolating compartment 310 and the second chemical substance 308 can be arranged solely inside the chamber 302.

[0201] FIG. 4 illustrates a chemical engine 400 configured to produce a pressurized working gas as a result of a chemical reaction. In operation, the chemical engine 400 can be integrated into a therapy electrode such as therapy electrode 200 as discussed above, e.g., replacing pressure source 240 as discussed in reference to therapy electrode 200. A controller, such as medical device controller 120, can be operably connected to the chemical engine 400. The medical device controller 120 can be configured to provide a triggering electrical signal to the chemical engine 400 prior to delivery of, for example, a therapeutic shock to a patient. The electrical signal can be configured to facilitate or otherwise initiate a chemical reaction configured to produce a pressurized working gas. The pressurized workingDocket No. Z2011-7092WO(Z20877WO-01)gas can then be directed through the fluid channel 230 to the conductive gel reservoirs 210, thereby causing release of the conductive gel stored therein.

[0202] The pressurized working gas can include any non-noxious gas. Examples are discussed above.

[0203] The chemical engine 400 can include a first chamber 402 configured to contain the chemicals and other components related to facilitating a chemical reaction. The chamber 402 can be formed such that it can define at least one working gas release aperture 404 for directing a pressurized working gas (produced by, for example, a chemical reaction within the chamber 402). Depending upon the design of the chemical engine 400, the working gas release aperture 404 can include a valve (e.g., a one-way flow valve) to prevent contamination or foreign chemicals from entering into the chamber 402. Similarly, the valve can be configured to open at a predetermined pressure (e.g., 10 psi (69 kPa)) to prevent chemicals from escaping the chamber 402 prior to the chemical reaction.

[0204] As described above in regard to the chamber 302, the first chamber 402 can be made from the same material(s) and has the same characteristics as discussed above with regard to chamber 302.

[0205] The chemical engine 400 can include a first chemical substance 406 and a second chemical substance 408. The first chemical substance 406 may be disposed within a first compartment defined by a portion of an interior volume of the first chamber 402. The first chemical substance 406 can be a metal carbonate or bicarbonate. In some implementations, the first chemical substance 406 can be a solid such as sodium bicarbonate loaded into the chamber 402 in, for example, a powder, or compressed solid form.

[0206] The second chemical substance 408 remains separated from the first chemical substance 406 by, for example, a plunger 410. The second chemical substance 408 may be disposed within a second compartment defined by a second portion of an interior volume of the chamber 402 or of the plunger 410. The ordinal terminology for the first and second compartments is arbitrary and the first compartment may be considered a second compartment while the second compartment may be considered a first compartment. The plunger 410 is configured to push at least one chemical substance, for example, second chemical substance 408 from the first compartment into the second compartment. In some implementations, the second chemical substance 408 is an acid.

[0207] The metal carbonate can be any metal carbonate, as discussed above.

[0208] The metal bicarbonate can be any metal bicarbonate as discussed above.

[0209] The acid can be any acid as discussed above.Docket No. Z2011-7092WG(Z20877WO-01)

[0210] In certain implementations, the plunger 410 can be constructed from a plastic such as polyethylene, or a metal such as stainless steel or aluminum. The plunger 410 may include one or more O-rings 411 positioned to prevent leakage of the second chemical substance 408. In some examples, the one or more O-rings 411 may be configured and arranged to act as a mechanical barrier configured to create a seal between the first chemical substance 406 and the second chemical substance 408. In some implementations, the O-rings 411 can be made from a thermoplastic elastomer such as synthetic rubber. The O-rings 411 can also be sized to produce a friction fit between the plunger 410 and the chamber 402.

[0211] To facilitate movement of the plunger 410, and thus mixing of the first chemical substance 406 and the second chemical substance 408, the plunger 410 can be connected to a mechanically or electrically actuated movement causing device such as a solenoid 412. The solenoid 412 can be configured to exert a pushing force on the plunger 410, thereby moving the plunger 410 toward the first chemical substance 406 (as shown in FIG. 4), causing the release of the second chemical substance 408 into the first chemical substance 406. The second chemical substance 408 can mix with the first chemical substance 406, thereby producing a pressurized working gas. In certain implementations, the shape of the chamber 402 can be configured and designed to direct the pressurized working gas out of the working gas release aperture 404. The working gas release aperture 404 can be connected to a fluid channel in, for example, the therapy electrode 200 as described above in regard to FIG. 2. The pressurized working gas can be directed through the fluid channel to one or more gel reservoirs, thereby facilitating release of conductive gel stored in the gel reservoirs.

[0212] In some examples, a chemical reaction initiator includes the plunger 410, or the combination of the plunger 410 and movement causing device, and is configured to initiate generation of a working gas by causing a chemical reaction involving the first chemical substance 406. In implementations, the chemical reaction initiator initiates release of the working gas out of the chamber 402 through the working gas release aperture 404 or to cause at least one chemical substance, such as the first chemical substance 406, and the second chemical substance 408 to come into contact with one another and generate the working gas.

[0213] Depending upon the electrical requirements of the solenoid 412, and desired timing for the release of the conductive gel, the medical device controller 120 can be configured to deliver an appropriate electrical signal (e.g., at a high enough current to move the solenoid 412) at the appropriate time (e.g., providing for adequate timing for the chemical reaction to occur and for the subsequent release of the conductive gel). In some implementations, the chemical engine 400 can also include a localized power source that, inDocket No. Z2011-7092WO(Z20877WO-01)response to the signal from the medical device controller 120, is configured to provide a current to the solenoid 412, thereby facilitating movement of the solenoid 412.

[0214] As noted above, the chemical engine 400 can be integrated into a therapy electrode such as therapy electrode 200. For example, the chemical engine 400 can replace pressure source 240 as discussed in reference to therapy electrode 200. A controller, such as medical device controller 120, can be operably connected to the chemical engine 400. The medical device controller 120 can be configured to provide an electrical signal to the chemical engine 400 prior to delivery of, for example, a therapeutic shock to a patient. The electrical signal can be directed to the solenoid 412. The solenoid 412 can move the plunger 410 toward, for example, working gas release aperture 404. Such movement of the plunger 410 can result in the second chemical substance 408 being released into the first chemical substance 406.

[0215] The second chemical substance 408 can mix with the first chemical substance 406, causing a chemical reaction. The chemical reaction can produce a pressurized working gas (e.g., pressurized carbon dioxide gas) which can be directed through the working gas release aperture 404. The pressurized working gas can flow through the fluid channel 230 to each of the conductive gel reservoirs 210. The pressurized working gas can facilitate release of the conductive gel contained within the conductive gel reservoirs 210, resulting in the conductive gel flowing through the apertures in the electrically conductive layer that is proximate the patient’s body. The medical device controller 120 can then deliver the therapeutic shock.

[0216] It should be noted that chemical engines 300 and 400 are described above by way of example only. Similarly, the chemicals described in relation to the chemical engines 300 and 400, as well as the resulting chemical reactions and pressurized working gas produced by those reactions are described by way of example only.

[0217] In some implementations, the chemical engine 400 can include a first chemical substance 406 and a second chemical substance 408, wherein the first chemical substance 406 and the second chemical substance 408 are selected to produce nitrogen gas or oxygen gas.

[0218] To produce oxygen gas, the first chemical substance 406 can be sodium chlorate, potassium perchlorate, potassium permanganate, potassium iodide, or mixtures thereof and the second chemical substance 408 can be hydrogen peroxide, barium peroxide, iron powder, or mixtures thereof. Yeast can be used as the first chemical substance 406 in some implementations. In some implementations, the second chemical substance 408 is hydrogen peroxide. In some implementations, the second chemical substance 408 is hydrogen peroxideDocket No. Z2011-7092WO(Z20877WO-01)and the first chemical substance 406 can be one or a mixture of potassium iodide, yeast, and potassium permanganate.

[0219] To produce nitrogen gas, the first chemical substance 406 can be an ammonium compound and the second chemical substance 408 can be a chemical substance that reacts with the ammonium compound to produce nitrogen gas. Examples of the ammonium compound include ammonium nitrite, ammonium nitrate, ammonium, chloride, ammonium dichromate, ammonium hydroxide, or mixtures thereof. Examples the second chemical substance 408 can be sodium nitrite, potassium nitrite, calcium nitrite, or other nitrite compound.

[0220] Nitrogen gas can also be produced by the reaction of hypochlorites or hypobromites on ammonia, reduction of nitric and / or nitrous oxides, reaction of ammonia gas with a nitrite compound, or combinations of these reactions.

[0221] As described above, a chemical engine can include two or more chemicals configured to mix such that a resulting reaction produces an amount of pressurized working gas such as carbon dioxide.

[0222] The pressurized working gas can include any non-noxious gas. Examples are discussed above.

[0223] In some implementations, the pressurized working gas is produced from mixing a first chemical substance and a second chemical substance to produce carbon dioxide, where the first chemical substance is a metal carbonate or bicarbonate and the second chemical substance is an acid. The reaction of the metal carbonate or bicarbonate with the acid produces safe byproducts including salt, water, and carbon dioxide as shown below in reaction (1):

[0224] Metal Carbonate or Bicarbonate+Acid^Salt+Water+Carbon Dioxide (1)

[0225] For example, the chemical reaction can include mixing an acid such as citric or acetic acid with a basic solid such as sodium bicarbonate to produce carbon dioxide gas with water, and sodium acetate. A specific chemical reaction example of reaction (1) is shown below in reaction (2):

[0226] NaHCO3+CH3COOH^CO2+H2O+CH3COONa (2)Docket No. Z2011-7092WO(Z20877WO-01)

[0227] The base can be added in an amount of about 0.001 grams to about 1000 grams. In some embodiments the base can be added in an amount of 0.001 to about 50 wt % of the total amount of the base and the acid. The acid can be added in an amount of about 0.001 grams to about 1000 grams. In some embodiments the acid can be added in an amount of 0.001 to about 50 wt % of the total amount of the base and the acid.

[0228] In certain implementations, the first chemical substance or the second chemical substance can be a limiting agent. For example, a specific quantity of the first chemical substance can be determined that, upon reaction, will produce an appropriate amount of pressurized working gas. An amount of the second chemical substance can be determined that would fully react with the specific quantity of the first chemical. In certain embodiments, an additional buffer amount of the second chemical substance can be included. For example, an additional 5-25% of the second chemical substance can be included. In such an example, the first chemical substance would act as a limiting agent as the first chemical substance would fully react with the second chemical substance (with an amount of excess second chemical substance remaining, i.e., the additional buffer).

[0229] In some embodiments, the base and the acid are present in an amount sufficient to produce an amount of carbon dioxide, which produces a pressure of from about 5 psi to about 100 psi (about 34.5 kPa to about 689 kPa). In some implementations, the pressure is from about 10 psi to about 70 psi (about 69 kPa to about 483 kPa). In some implementations, the pressure is from about 15 psi to about 50 psi (about 103 kPa to about 345 kPa). In some implementations, the pressure is from about 15 psi to about 35 psi (about 103 kPa to about 241 kPa).

[0230] As noted above, a specific amount of pressurized working gas can be created during the chemical reaction, the pressurized working gas being directed to individual gel reservoirs of a therapy electrode to facilitate release of conductive gel stored therein. For example, the pressurized working gas can be configured to fill an internal volume of 25 cm3to a pressure of approximately 50 psi (345 kPa) (e.g., a 35 psi (241 kPa) pressure to facilitate release of the conductive gel from the gel reservoirs plus a 15 psi (103 kPa) safety buffer to account for any unreacted chemicals or other potential complications during the chemical reaction). In the above example chemical reaction, the resulting pressurized working gas is carbon dioxide, which has a molar mass of 44.0095 g / mol at room temperature (e.g., approximately 295 K). As such, based upon the desired pressure (50 psi (345 kPa) at standard atmospheric pressure), the internal volume (25 cm3), and the molar mass of the carbonDocket No. Z2011-7092WG(Z20877WO-01)dioxide, an amount of carbon dioxide to be produced during the chemical reaction can be calculated using the ideal gas law:

[0231] pV=nRT (3)

[0232] where p is the pressure, V is the volume, n is the number of moles of the gas (represented as mass / mass of 1 mole), R is the ideal gas constant (8.31446 J K-1mol-1), and T is the temperature at the time of reaction (e.g., approximately 295 K or room temperature). As noted above, the pressure includes a safety buffer. This buffer can also be used to account for any changes in temperature during the reaction.

[0233] Substituting the values as noted above into the ideal gas law, the resulting equation is:

[0234] (50 psi (345 kPa) at 1 atm)(25 cm3)=(mass of C02 / 44.0095 g / mol)(8.31441 J K-1moF1)(295 K).

[0235] Converting both pressure and volume to appropriate units (Pascal and cubic meters respectively) results in:

[0236] (344737.86 Pa)(0.000025 m3)=(mass of C02 / 44.0095 g / mol)(8.31446 J K-1moF1)(295 K).

[0237] Solving the above equation gives a mass of 0.15 g of CO2to be produced. Such a mass of CO2will result in the desired 50 psi (345 kPa) in the internal volume of 25 cm3. CO2has a density of about 1.98 g / L in its gaseous state. As such, the above equation results in 0.075 liters of CO2. Thus, a chemical reaction that produces 0.075 liters of CO2will result in a 50 psi (345 kPa) pressure in the internal volume of 25 cm3.

[0238] In the chemical engine of FIG. 3, when the controller, e.g., medical device controller 120, triggers a release of the conductive gel, the wire 312 can be heated, thereby causing a structural compromise of the isolating compartment 310 (e.g., the wire 312 melts a hole in isolating compartment 310). The second chemical substance 308, for example, acetic acid can then be released from the isolating compartment 310. In certain implementations, leaf springs 314 (or other external pressure applying device) can provide an external force against the isolating compartment 310, causing quicker release of the acetic acid. The acetic acid can then mix with the first chemical substance 306, for example, sodium bicarbonate in the chamber 302, causing creation of the carbon dioxide gas. The carbon dioxide gas can be directed out of the chamber 302 via the working gas release aperture 304. The carbon dioxideDocket No. Z2011-7092WO(Z20877WO-01)gas can then be directed by one or more fluid conduits, such as fluid channel 230, to the gel reservoirs of a therapy electrode.

[0239] In certain implementations, the speed of the reaction can be an important consideration. For example, in a wearable defibrillator, when a treatment shock is imminent, it may be desirable to have the conductive gel deploy as quickly as possible. In such an implementation, the amounts of the chemicals can be changed to produce a quicker reaction. For example, the amounts of sodium bicarbonate and acetic acid can be increased. In certain implementations, a chemical engine can include between 0.50 grams and 2.5 grams of sodium bicarbonate. Similarly, a chemical engine can include between 0.40 grams and 2.2 grams of acetic acid. In a particular example, a chemical engine can include 1.5 grams of sodium bicarbonate and 0.50 grams of acetic acid. As the acetic acid is used in a liquid state, a lower ratio (as compared to the total amount of chemicals used in the reaction) of acetic acid can be used as compared to the ratio of the solid sodium bicarbonate. By including a higher ratio of the sodium bicarbonate, the chances are increased that the acetic acid will fully react with the sodium bicarbonate, thereby maximizing the amount of carbon dioxide gas that can be produced by the amount of acetic acid used. Any excess sodium bicarbonate will remain in the chemical engine in an unreacted state.

[0240] As noted above, the internal volume that the pressurized working gas is intended to fill can vary between implementations as well. For example, as noted above, the total internal volume can vary between 10-50 cm3. When the internal volume is less than the volume as used in the above calculations (25 cm3), the amount of the individual chemicals can be reduced as a lesser amount of pressurized working gas may be used. Conversely, when the internal volume is greater than the volume as used in the above calculations, the amount of the individual chemicals can be increased as a greater amount of pressurized working gas may be used. For example, a pressure source can include between 0.25 grams and 5 grams of sodium bicarbonate. Similarly, a chemical engine can include between 0.15 and 4 grams of acetic acid.

[0241] In addition to changing the quantities of the chemicals used, changing the chemicals reacting with one another to produce a different gas can be used to control both the volume of gas produced and speed of a reaction. Instead of producing carbon dioxide, as discussed above, oxygen or nitrogen can be generated from a chemical reaction.

[0242] In some implementations, the chemical engine 300 can include a first chemical substance 306 and a second chemical substance 308, wherein the first chemical substance 306 and the second chemical substance 308 are selected to produce nitrogen gas or oxygen gas.Docket No. Z2011-7092WO(Z20877WO-01)

[0243] To produce oxygen gas, the first chemical substance 306 can be sodium chlorate, potassium perchlorate, potassium permanganate, potassium iodide, or mixtures thereof and the second chemical substance 308 can be hydrogen peroxide, barium peroxide, iron powder, or mixtures thereof. Yeast can be used as the first chemical substance 306 in some implementations. In some implementations, the second chemical substance 308 is hydrogen peroxide. In some implementations, the second chemical substance 308 is hydrogen peroxide and the first chemical substance 306 can be one or a mixture of potassium iodide, yeast, and potassium permanganate.

[0244] To produce nitrogen gas, the first chemical substance 306 can be an ammonium compound and the second chemical substance 308 can be a chemical substance that reacts with the ammonium compound to produce nitrogen gas. Examples of the ammonium compound include ammonium nitrite, ammonium nitrate, ammonium, chloride, ammonium dichromate, ammonium hydroxide, or mixtures thereof. Examples the second chemical substance 308 can be sodium nitrite, potassium nitrite, calcium nitrite, or other nitrite compound.

[0245] Nitrogen gas can also be produced by the reaction of hypochlorites or hypobromites on ammonia, reduction of nitric and / or nitrous oxides, reaction of ammonia gas with a nitrite compound, or combinations of these reactions.

[0246] For example, the chemical reaction can include mixing an aqueous peroxide such as hydrogen peroxide with a metallic salt such as potassium iodide to produce oxygen gas. Such a reaction results in the catalyzed decomposition of the hydrogen peroxide to produce water and oxygen gas. Specifically, the hydrogen peroxide reacts with iodide ions from the potassium iodide to produce the oxygen gas. For example, the reactions can be represented as:

[0247] H2O2+r^H2O+IO- (4)

[0248] H2O2+IO-^H2O+O2+F (5)

[0249] where H2O2is hydrogen peroxide, T is an iodide ion, H2O is water, IO is a hypoiodite ion, and O2is oxygen gas.

[0250] As noted above, a specific amount of pressurized working gas can be created during the chemical reaction, the pressurized working gas being directed to individual gel reservoirs of a therapy electrode to facilitate release of conductive gel stored therein. For example, the pressurized working gas can be configured to fill an internal volume of 10 cm3Docket No. Z2011-7092WO(Z20877WO-01)to a pressure of approximately 50 psi (345 kPa) (e.g., a 35 psi (241 kPa) pressure to facilitate release of the conductive gel from the gel reservoirs plus a 15 psi (103 kPa) safety buffer to account for any unreacted chemicals or other potential complications during the chemical reaction). In the above example chemical reaction, the resulting pressurized working gas is oxygen gas, which has a molar mass of 32.00 g / mol at room temperature (e.g., approximately 295 K). As such, based upon the desired pressure (50 psi (345 kPa) at standard atmospheric pressure), the internal volume (25 cm3), and the molar mass of the oxygen, an amount of oxygen to be produced during the chemical reaction can be calculated using the ideal gas law.

[0251] Substituting the values as noted above into the ideal gas law, the resulting equation is:

[0252] (50 psi (345 kPa) at 1 atm)(25 cm3)=(mass of 02 / 32.00 g / mol)(8.31441 J K-1mol’1)(295 K).

[0253] Converting both pressure and volume to appropriate units (Pascal and cubic meters respectively) results in:

[0254] (344737 Pa)(0.000025 m3)=(mass of 02 / 32.00 g / mol)(8.31441 J K-1mol’1)(295 K).

[0255] Solving the above equation gives a mass of 0.11 g of O2to be produced. Such a mass of O2will result in the desired 50 psi (345 kPa) in the internal volume of 25 cm3. O2has a density of 1.43 g / L in its gaseous state. As such, the above equation results in 0.077 liters of O2. Thus, a chemical reaction that produces 0.077 liters of O2will result in a 50 psi (345 kPa) pressure in the internal volume of 25 cm3.

[0256] The amount of hydrogen peroxide and potassium iodide to include can be determined based upon the resulting amount of O2produced. As noted above, 0.11 g of O2produces a pressure that will result in release of the conductive gel from the conductive gel reservoirs of a therapy electrode as described above. As noted above, O2has a molar mass of 32.00 g / mol. As such, 0.11 g equals approximately 0.0046 moles of O2. As such, approximately 0.0046 moles of both potassium iodide and hydrogen peroxide should be included in the reaction. Hydrogen peroxide has a molar mass of 34.015 g / mol. As such, approximately 0.0046 moles of hydrogen peroxide is 0.16 grams. Potassium iodide has a molar mass of 166.00 g / mol. As such, approximately 0.0046 moles of potassium iodide is 0.76 grams. As such, to produce 0.11 grams of O2, at least 0.16 grams of hydrogen peroxide should fully react with 0.76 grams of potassium iodide.

[0257] Thus, in certain implementations of the chemical engines 300 and 400 as described above, approximately 0.76 grams of potassium iodide (e.g., in a powdered form)Docket No. Z2011-7092WG(Z20877WO-01)can be used for the first chemical, and approximately 0.16 grams of hydrogen peroxide can be used for the second chemical. Thus, in a particular example referring to chemical engine 300 as shown in FIG. 3, approximately 0.76 grams of powdered potassium iodide can be loaded into the chamber 302. Similarly, approximately 0.16 grams of hydrogen peroxide can be loaded into isolating compartment 310.

[0258] In the chemical engine of FIG. 3, when the controller, e.g., medical device controller 120, triggers a release of the conductive gel, the wire 312 can be heated, thereby causing a structural compromise of the isolating compartment 310 (e.g., the wire 312 melts a hole in isolating compartment 310). The hydrogen peroxide can then be released from the isolating compartment 310. In certain implementations, leaf springs 314 can provide an external force against the isolating compartment 310, causing quicker release of the hydrogen peroxide. The hydrogen peroxide can then mix with the potassium iodide in the chamber 302, causing catalytic decomposition of the hydrogen peroxide into water and oxygen gas. The oxygen gas can be directed out of the chamber 302 via the working gas release aperture 304. The oxygen gas can then be directed by one or more fluid conduits of a therapy electrode, such as fluid channel 230, to the gel reservoirs.

[0259] As described above, the speed of the reaction can be an important consideration. To adjust the reaction speed, the amounts of hydrogen peroxide and potassium iodide can be increased. In certain implementations, a chemical engine can include between 0.20 grams and 2.5 grams of hydrogen peroxide. Similarly, a chemical engine can include between 0.80 grams and 5.0 grams of potassium iodide. In a particular example, a chemical engine can include 0.5 grams of hydrogen peroxide and 1.50 grams of potassium iodide.

[0260] Chemical engines as disclosed herein generate and provide a pressurized working gas for use in causing the release of conductive gel from a therapy electrode as described above prior to administering electrical therapy to a patient. In some embodiments, depending upon the particular types and amounts of chemical substances utilized to react and generate the pressurized working gas, portions of one or more of the chemical substances may remain unreacted or may produce a reaction product other than the pressurized working gas. It has been found desirable that in operation substances other than the pressurized working gas, for example, unreacted chemical substances or non-gaseous reaction products be prevented from exiting a chemical engine. Accordingly, chemical engines as disclosed herein may be provided with one or more forms of chemical substance arrest material. The chemical substance arrest material may be configured to retain the unreacted chemical substance(s) orDocket No. Z2011-7092WG(Z20877WO-01)non-gaseous reaction products thereby preventing the unreacted chemical substance(s) or non-gaseous reaction products from passing out of the chemical engine.

[0261] One example of a chemical engine including a chemical substance arrest material is illustrated in FIG. 5. The chemical engine illustrated in FIG. 5 is a modification to chemical engine 300 illustrated in FIG. 3 and is thus given the indicator number 300’. The chemical engine 300’ includes a first chamber 302 as described with respect to chemical engine 300 that is configured to contain at least one chemical substance, for example, first chemical substance 306 and second chemical substance 308. The isolating compartment 310 housing the second chemical substance 308 may be considered a first compartment while the volume within the first chamber 302 housing the first chemical substance 306 may be considered a second compartment.

[0262] A second chamber 316 is coupled to the first chamber 302. A chemical substance arrest material 318 is configured to be disposed within the second chamber 316 and is illustrated as being disposed within the second chamber 316.

[0263] The chemical substance arrest material 318 may be selected based on the types and quantities of reactant chemical substances 306, 308 in the chemical engine 300’ and their associated reaction products. For example, if one or both of the reactant chemical substances 306, 308 or a reaction product thereof is a liquid, the chemical substance arrest material 318 may be a material configured to absorb the one or both of the reactant chemical substances 306, 308 or the reaction product thereof. In such implementations, the chemical substance arrest material 318 may comprise or consist of, for example, natural sponge, synthetic sponge, silica gel particles, cotton, or a combination of any of the foregoing. In some implementations, the chemical substance arrest material 318 may comprise or consist of any other suitable material that may absorb the particular liquid reactant chemical substance(s) or reaction product.

[0264] If at least one of the reactant chemical substances 306, 308 or a reaction product thereof is a solid, for example, in the form of solid particulates, the chemical substance arrest material 318 may include or consist of a filter configured to retain the at least one chemical substance or reaction product. In such implementations, the chemical substance arrest material 318 may include or consist of a particle filter, for example, a screen, a membrane filter, or other suitable form of particle filter.

[0265] In some examples, if at least one of the reactant chemical substances 306, 308 or a reaction product thereof has a non-neutral pH, the chemical substance arrest material 318 may include or consist of a neutralization agent configured to neutralize the pH of the at leastDocket No. Z2011-7092WG(Z20877WO-01)one of the reactant chemical substances 306, 308 or the reaction product thereof. For example, in such implementations, the chemical substance arrest material 318 can include an acid or a buffer if one or more of the chemical substances or reaction product has a basic pH or may include a base or a buffer if one or more of the chemical substances or reaction product has an acidic pH.

[0266] A working gas release aperture 320 is defined in wall of the second chamber 316. The working gas release aperture 304 defined in a wall of the first chamber 302 may thus be considered a first working gas release aperture 304 while the working gas release aperture 320 defined in the wall of the second chamber 316 may be considered a second working gas release aperture 320. The conductive gel receptacles 210 of a therapy electrode may be in fluid communication with the second working gas release aperture 320 and the chemical engine 300’ may be configured to cause the generated working gas to pass through both the first working gas release aperture 304 and the second working gas release aperture 320.

[0267] Another embodiment of a chemical engine 400’, illustrated in FIG. 6 is a modification to the chemical engine 400 of FIG. 4. The chemical engine 400 has been modified to result in the chemical engine 400’ in a similar manner as chemical engine 300 is modified to result in chemical engine 300’. In chemical engine 400’ chamber 402 may be considered a first chamber to which a second chamber 416, including a chemical substance arrest material 418 configured to be disposed within the second chamber 416, is coupled. The chemical substance arrest material 418 may have any of the compositions, properties, or functions discussed above with respect to chemical substance arrest material 318. The working gas release aperture 404 defined in the wall of the first chamber 402 may be considered a first working gas release aperture 404, while aperture 420 defined in the wall of the second chamber 416 may be considered a second working gas release aperture.

[0268] Another embodiment of a chemical engine 700 is illustrated in FIG. 7. The chemical engine 700 includes a first chamber 702 that includes a first compartment 724 housing at least one chemical substance, for example, a first chemical substance 706, and a second compartment 726 housing a second chemical substance 708. An orifice or aperture 728 is defined in a wall separating the first compartment 724 from the second compartment 726. A second chamber 716 is coupled to the first chamber 702. The second chamber 716 houses a chemical substance arrest material 718 that may have any of the compositions, properties, or functions discussed above with respect to chemical substance arrest materials 318 or 418. A first working gas release aperture 704 is defined in a wall common to and separating the first chamber 702 and the second chamber 716. A second working gas releaseDocket No. Z2011-7092WG(Z20877WO-01)aperture 720 is defined in another wall of the second chamber 716 opposite the wall including the first working gas release aperture 704. A rupturable seal 722 obstructs the first working gas release aperture 704. A rupturable barrier 723 obstructs the orifice 728 separating the two compartments 724, 726. A mechanical chemical reaction initiator 730 includes a plunger 710 and a spring 712 biasing the plunger 710 into the first compartment 724. The rupturable barrier 723 between the first compartment 724 and the second compartment 726 is configured to separate the at least one chemical substance 706 from the second chemical substance 708 prior to an action taken by the chemical reaction initiator 730. The plunger 710 is restrained by a meltable wire 732, for example a nickel chromium wire, that may melt and release the plunger 710 to be propelled into the first compartment 724 by the spring 712 responsive to sufficient current passed through the meltable wire 732 from electrical leads 734. The chemical reaction initiator 730 is configured to break the rupturable barrier 723 between the first compartment 724 and the second compartment 726 by applying pressure to one of the at least one chemical substance 706 or the second chemical substance 708, specifically to the at least one chemical substance 706 in the embodiment of FIG. 7. The plunger 710 may then push the first chemical substance 706 from the first compartment 724 into the second compartment 726 to react with the second chemical substance 708. The first and second chemical substances 706, 708 may be any of the chemical substances discussed above that may react with one another to form a pressurized working gas. The movement causing device of the present example, as provided by the spring 712 and the meltable wire 732, may be applied to other embodiments.

[0269] In another embodiment of a chemical engine as disclosed herein one of the reactant chemical substances is a liquid that is releasably housed in a syringe until the chemical reaction is to be performed. As illustrated in FIG. 8, chemical engine 800 includes a chemical reaction initiator 830 in the form of a syringe and an actuator 832 such as a solenoid. The first chemical substance 806 is releasably housed in the barrel of the syringe, so the barrel of the syringe is both part of the chemical reaction initiator and defines the first compartment 824. The needle of the syringe extends into the second compartment 826 which houses the second chemical substance 808. The first chemical substance 806 may be or may include any of the liquid chemical reactants discussed above and the second chemical substance 808 may be or may include any of the liquid or solid chemical reactants discussed above. The first chamber 802 includes the second compartment 826 and the syringe and actuator 832 as well as any housing for same if present. A second chamber 816 housing the chemical substance arrest material 818 is coupled to the first chamber 802, specifically to theDocket No. Z2011-7092WG(Z20877WO-01)second compartment 826. The chemical substance arrest material 818 may be any form of chemical substance arrest material as discussed above and may be selected based on the one or more chemicals selected for the first chemical substance 806 and second chemical substance 808. In use, the first chemical substance 806 is introduced into the second compartment 826 by the syringe where the first chemical substance 806 contacts and reacts with the second chemical substance 808 to form a pressurized working gas. The pressurized working gas exits the chemical engine 800 through a working gas release aperture 804 that is in fluid communication with a fluid channel 230 and conductive gel reservoirs 210 of a therapy electrode 200 such as that illustrated in FIG. 2. A rupturable seal 822 may be provided to obstruct the working gas release aperture 804 prior to the generation of the pressurized working gas to prevent the second chemical substance 808 from prematurely exiting the chemical engine 800. The rupturable seal 822 may be ruptured by the generated pressurized working gas. In contrast to the chemical engines 300’, 400’, and 700 discussed above, the pressurized working gas does not flow through the second chamber 816. The second chamber 816 is coupled to a wall of the second compartment 826 other than the wall in which the working gas release aperture 804 is defined. The second chamber 816 is fluid communication with the interior of the second compartment 826 via an aperture 836 defined in a wall separating the internal volumes of the second chamber 816 and second compartment 826 from one another. Unreacted chemical substances 806, 808 or non-gaseous byproducts of the chemical reaction between the chemical substances 806, 808 may be pushed into the second compartment 826 by the pressurized working gas, fall into the second compartment 826 by the force of gravity, and / or be wicked into the second compartment by the chemical substance arrest material 818 and may be absorbed by, trapped in, or otherwise be retained within the second compartment 826 by the chemical substance arrest material 818.

[0270] In an embodiment of a chemical engine as disclosed herein in which one of the reactant chemical substances is a solid, for example, in the form of a powder or as a granular material, the mechanical chemical reaction initiator may include a screw pump. As illustrated in FIG. 9, chemical engine 900 includes a mechanical chemical reaction initiator 930 in the form of a screw and an actuator 932 such as an electric motor. The screw extends into a housing defining the first compartment 924 that houses the solid first chemical substance 906. Upon actuation of electric motor 932, the screw turns and pushes the first chemical substance out of the first compartment 924, through an aperture 938 in a wall separating the first compartment 924 and into the second compartment 926 in which the first chemical substance 906 contacts and reacts with the second chemical substance 908. In some embodiments aDocket No. Z2011-7092WG(Z20877WO-01)rupturable barrier 923 obstructs the aperture 938 to prevent premature contact and reaction between the first and second chemical substances 906, 908. The first chemical substance 906 may be or may include any of the solid chemical reactants discussed above and the second chemical substance 908 may be or may include any of the liquid or solid chemical reactants discussed above. The first chamber 902 includes the second compartment 926 and the screw and actuator / electric motor 932 as well as any housing for same if present. A second chamber 916 housing the chemical substance arrest material 918 is coupled to the first chamber 902, specifically to the second compartment 926. The chemical substance arrest material 918 may be any form of chemical substance arrest material as discussed above and may be selected based on the one or more chemicals selected for the first chemical substance 906 and second chemical substance 908. Reaction between the first chemical substance 906 and second chemical substance 908 generates a pressurized working gas. The pressurized working gas exits the chemical engine 900 through a working gas release aperture 904 that is in fluid communication with a fluid channel 230 and conductive gel reservoirs 210 of a therapy electrode 200 such as that illustrated in FIG. 2. A rupturable seal 922 may be provided to obstruct the working gas release aperture 904 prior to the generation of the pressurized working gas to prevent the second chemical substance 908 from prematurely exiting the chemical engine 900. The rupturable seal 922 may be ruptured by the generated pressurized working gas. In contrast to the chemical engines 300’, 400’, and 700 discussed above, and like the chemical engine 800, the pressurized working gas does not flow through the second chamber 916. The second chamber 916 is coupled to a wall of the second compartment 926 other than the wall in which the working gas release aperture 904 is defined. The second chamber 916 is fluid communication with the interior of the second compartment 926 via an aperture 936 defined in a wall separating the internal volumes of the second chamber 916 and second compartment 926 from one another. Unreacted chemical substances 906, 908 or non-gaseous byproducts of the chemical reaction between the chemical substances 906, 908 may be pushed into the second chamber 916 by the pressurized working gas, fall into the second chamber 916 by the force of gravity, and / or be wicked into the second chamber 916 by the chemical substance arrest material 918 and may be absorbed by, trapped in, or otherwise be retained within the second chamber 916 by the chemical substance arrest material 918 .

[0271] In an embodiment of a chemical engine as disclosed herein in which one of the reactant chemical substances is a liquid, the chemical engine may be thermally activated and the chemical reaction initiator may include a source of heat, for example a wire that heats responsive to the passage of current therethrough. As illustrated in FIG. 10A, chemicalDocket No. Z2011-7092WG(Z20877WO-01)engine 1000 includes a chemical reaction initiator 1030 in the form of an electrical resistance heater 1038, for example, a length of resistive wire that heats responsive to passage of a current therethrough. The electrical resistance heater 1038 is disposed within a housing defining the first compartment 1024 that houses the first chemical substance 1006 which may be or may include any of the liquid chemical reactants described above. The chemical resistance heater is in thermal contact with the first chemical substance 1006. In some embodiments, the electrical resistance heater 1038 may include a protective coating to prevent attack by the first chemical substance 1006. Alternatively, the electrical resistance heater 1038 may surround the first compartment 1024 or be embedded in a wall of the first compartment 1024 and be in indirect thermal contact with the first chemical substance 1006. Upon passage of current through the electrical resistance heater 1038, the electrical resistance heater 1038 heats up and in turn heats the first chemical substance 1006. The first chemical substance 1006 expands as it is heated and the pressure of the first chemical substance 1006 increases because it is sealed in a fixed volume in the first compartment by a rupturable barrier 1023 covering an aperture in a wall of the first compartment 1024 separating the first compartment 1024 from the second compartment 1026. Once the first chemical substance 1006 heats sufficiently so that it builds up sufficient pressure to rupture the rupturable barrier 1023 covering the aperture in the wall of the first compartment 1024 it escapes through the aperture in the wall separating the first compartment 1024 and the second compartment 1026 and contacts and reacts with the second chemical substance 1008 in the second compartment 1026. The second chemical substance 1008 may be or may include any of the liquid or solid chemical reactants discussed above. The first chamber 1002 includes the first compartment 1024 and the second compartment 1026. A second chamber 1016 housing the chemical substance arrest material 1018 is coupled to the first chamber 1002, specifically to the second compartment 1026. The chemical substance arrest material 1018 may be any form of chemical substance arrest material as discussed above and may be selected based on the one or more chemicals selected for the first chemical substance 1006 and second chemical substance 1008. Reaction between the first chemical substance 1006 and second chemical substance 1008 generates a pressurized working gas. The pressurized working gas exits the chemical engine 1000 through a working gas release aperture 1004 that is in fluid communication with a fluid channel 230 and conductive gel reservoirs 210 of a therapy electrode 200 such as that illustrated in FIG. 2. A second rupturable seal 1022 may be provided to obstruct the working gas release aperture 1004 prior to the generation of the pressurized working gas to prevent the second chemical substance 1008 from prematurelyDocket No. Z2011-7092WG(Z20877WO-01)exiting the chemical engine 1000. The second rupturable seal 1022 may be ruptured by the generated pressurized working gas. As in the chemical engines 800, 900 the pressurized working gas does not flow through the second chamber 1016. The second chamber 1016 is coupled to a wall of the second compartment 1026 other than the wall in which the working gas release aperture 1004 is defined. The second chamber 1016 is fluid communication with the interior of the second compartment 1026 via an aperture 1036 defined in a wall separating the internal volumes of the second chamber 1016 and second compartment 1026 from one another. Unreacted chemical substances 1006, 1008 or non-gaseous byproducts of the chemical reaction between the chemical substances 1006, 1008 may be pushed into the second compartment 1026 by the pressurized working gas, fall into the second compartment 1026 by the force of gravity, and / or be wicked into the second compartment by the chemical substance arrest material 1018 and may be absorbed by, trapped in, or otherwise be retained within the second compartment 1026 by the chemical substance arrest material 1018.

[0272] A variation of the chemical engine 1000 is illustrated in FIG. 10B, indicated generally at 1000’. In chemical engine 1000’, instead of heating the first chemical substance 1006 to cause it to expand and rupture the barrier 1023 between the first compartment 1024 and the second compartment 1026, the electrical resistance heater 1038 is used to heat a working fluid 1040, for example, a liquid also disposed within the first compartment 1024. Heating of the working fluid 1040 causes the working fluid 1040 to expand and push a plunger 1042 against the first chemical substance 1006. This causes the pressure of the first chemical substance 1006 to increase until it breaks the barrier 1023 between the first compartment 1024 and the second compartment 1026 and enters the second compartment 1026 to react with the second chemical substance 1008 and produce the pressurized working gas as described above. In this example, the chemical reaction initiator 1030 includes the combination of the electrical resistance heater 1038, working fluid 1040, and plunger 1042. In scenarios, this example may be advantageous in that there is less concern regarding the first chemical substance 1006 attacking the electrical resistance heater 1038. Further, if the working fluid 1040 has a greater coefficient of thermal expansion than the first chemical substance 1006, less heat / energy may be utilized to cause a similar increase in pressure of the first chemical substance 1006 than if the first chemical substance 1006 was heated directly. The combination of the electrical resistance heater 1038, working fluid 1040, and plunger 1042 acting as an actuator may be applied in other embodiments.

[0273] A variation of the chemical engine 1000’ is illustrated in FIG. 10C, indicated generally at 1000”. In chemical engine 1000”, instead of causing movement of the plungerDocket No. Z2011-7092WG(Z20877WO-01)1042 and pressurization of the first chemical substance 1006 by heating a working fluid 1040 as in chemical engine 100’, the plungerl024 may be caused to move and pressurize the first chemical substance 1006 to cause it to rupture the barrier 1023 between the first compartment 1024 and the second compartment 1026 by the use of an electromagnetic force. The plunger 1024 may be formed from or include a ferromagnetic or ferrimagnetic material, for example, iron, nickel, or cobalt or oxides thereof. An electromagnet 1044 may be provided that creates a magnetic field that pulls the plunger 1024 against the first chemical substance to cause an increase in pressure in the first chemical substance 1006 until the barrier 1023 between the first compartment 1024 and the second compartment 1026 ruptures and the first and second chemical substances come into contact and react to generate the pressurized working fluid. In chemical engine 1000” the combination of the electromagnet 1044 and plunger 1042 may be considered components of the chemical reaction initiator 1030. Chemical engine 1000” may be said to be magnetically actuated.

[0274] In other embodiments, a chemical engine may be actuated by breaking a barrier separating a first compartment containing at least a first chemical substance and second compartment containing at least a second chemical substance by an action taken directly on the barrier by a chemical reaction initiator. Illustrated in FIG. 11A is a chemical engine 1100 in which the chemical reaction initiator 1130 includes a line or cable 1148 having an end coupled to a barrier 1123 separating a first compartment 1124 containing at least a first chemical substance 1106 from a second compartment 1126 containing at least a second chemical substance 1108. The other end of the line or cable 1148 is connected to a tension generator 1146, for example, an electric motor, solenoid, spring, or other apparatus configured to pull on the line or cable 1148. The tension generator 1146 pulls on the line or cable 1148 which in turn applies tension to the barrier 1123 separating the first compartment 1124 from the second compartment 1126. This tension may cause the barrier 1123 to mechanically break or, in embodiments in which the barrier 1123 separating the first compartment 1124 from the second compartment 1126 is removably disposed between the first compartment 1124 and the second compartment 1126, the tension may displace the barrier 1123 from between the first compartment 1124 and the second compartment 1126 thereby providing for the at least one first chemical substance 1106 and the at least one second chemical substance 1108 to come into contact with one another in either or both of the first compartment 1124 or the second compartment 1126 and generate the working gas.Elements 1102, 1116, 1118, 1136, 1104, and element 1122 covering aperture 1104 may have the same structures and functions as corresponding elements 1002, 1016, 1018, 1036, 1004,Docket No. Z2011-7092WG(Z20877WO-01)and element 1022 covering aperture 1004 as described above with reference to chemical engines 1000, 1000’, and 1000”.

[0275] In a variation of the chemical engine 1100, instead of mechanically breaking, rupturing, or displacing the barrier 1123 between the first compartment 1124 and the second compartment 1126, the barrier 1123 between the first compartment 1124 and the second compartment 1126, or at least a portion thereof may be melted to provide for the at least one first chemical substance 1106 and the at least one second chemical substance 1108 to come into contact with one another in either of both of the first compartment 1124 or the second compartment 1126 and generate the working gas. As illustrated in FIG. 11B, chemical engine 1100’ may include a current source 1150, which may be included the medical device controller 120 of the medical device 100. To initiate contact and reaction between the at least one first chemical substance 1106 and the at least one second chemical substance 1108, the current source 1150 applies a current through electrical lines 1152 to an electrical heater 1154 located proximate to, in contact with, or embedded within the barrier 1123 between the first compartment 1124 and the second compartment 1126 to melt the barrier 1123. The barrier 1123 between the first compartment 1124 and the second compartment 1126 may be formed from or include a material that melts at a relatively low temperature, for example, wax or a polymer with a low melting point. Alternatively, the barrier 1123 between the first compartment 1124 and the second compartment 1126 may be formed of or include a thin metal foil and the current may be applied directly through the thin metal foil to melt the barrier 1123 between the first compartment 1124 and the second compartment 1126. The current source 1150, electrical lines 1152, and electrical heater 1154 (or the barrier 1123 between the first compartment 1124 and the second compartment 1126) may be considered components of the chemical reaction initiator 1130.

[0276] In chemical engines 800 - 1100’ the second compartment housing the chemical substance arrest material is illustrated coupled to the second chamber, but not in the path of the pressurized working gas generated by reaction between the first and second chemical substances. Any of these embodiments may be modified such that the second compartment housing the chemical substance arrest material is coupled to the second chamber in the path of the pressurized working gas generated by reaction between the first and second chemical substances and including a second gas release aperture such as is illustrated with respect to any of chemical engines 300’, 400’, or 700.

[0277] In further embodiments the second compartment housing the chemical substance arrest material may not only be coupled to the first compartment including the first andDocket No. Z2011-7092WO(Z20877WO-01)second chambers housing the reactant chemical substances, but may at least partially surround the first compartment. As shown in the example of FIG. 12, chemical engine 1200 includes a first compartment 1202, including the first and second chambers 1224, 1226 separated by a rupturable barrier 1223 and housing the reactant chemical substances 1206, 1208, that is surrounded by a second compartment 1216 housing the chemical substance arrest material 1218. The reactant chemical substances 1206, 1208 and chemical substance arrest material 1218 may have any of the compositions or properties of the reactant chemical substances and chemical substance arrest materials discussed above. The second chamber includes a first working gas release aperture 1204, optionally obstructed by a rupturable seal 1222. The second compartment 1216 includes a second working gas release aperture 1220. In use, working gas generated by a reaction between the reactant chemical substances 1206, 1208 passes through the first working gas release aperture 1204 and into the second compartment 1216 where particulates or liquid droplets that may be carried by the working gas are retained by the chemical substance arrest material 1218. The particle and liquid free working gas then exits the second working gas release aperture 1220 and is directed into a fluid channel 230 and conductive gel reservoirs 210 of a therapy electrode 200 such as that illustrated in FIG. 2. Solid or liquid substances entrained in the generated working gas or that may leak from portions of the chemical engine are absorbed or otherwise retained in the chemical substance arrest material 1218 in the second compartment 1216.

[0278] In one or more examples, the pressurized working gas acts directly on the gel in the gel reservoirs such that the working gas physically contacts the gel. In other examples, a diaphragm or other barrier may be present in the gel reservoirs such that the pressurized working gas acts to eject the conductive gel by hydraulic pressure but with a barrier therebetween configured to prevent physical contact between the working gas and the gel.

[0279] Although the patient matter contained herein has been described in detail for the purpose of illustration, it is to be understood that such detail is solely for that purpose and that the present disclosure is not limited to the disclosed embodiments, but, on the contrary, is intended to cover modifications and equivalent arrangements that are within the spirit and scope of the appended claims. For example, it is to be understood that the present disclosure contemplates that, to the extent possible, one or more features of any embodiment can be combined with one or more features of any other embodiment.

[0280] Other examples are within the scope and spirit of the description and claims.Additionally, certain functions described above can be implemented using software, hardware, firmware, hardwiring, or combinations of any of these. Features implementingDocket No. Z2011-7092WO(Z20877WO-01)functions can also be physically located at various positions, including being distributed such that portions of functions are implemented at different physical locations.

Claims

Docket No. Z2011-7092WO(Z20877WO-01)What is claimed is:CLAIMS1. A therapy electrode system for use in delivering electrical therapy, comprising:a conductive gel deployment chemical engine comprising:a first chamber configured to contain at least one chemical substance, a first working gas release aperture defined in a wall of the first chamber; a second chamber coupled to the first chamber, anda chemical substance arrest material configured to be disposed within the second chamber, the chemical substance arrest material configured to retain the at least one chemical substance thereby preventing the at least one chemical substance from passing out of the chemical engine, anda chemical reaction initiator configured toinitiate generation of a working gas by causing a chemical reaction involving the at least one chemical substance, andinitiate release of the working gas out of the first chamber through the first working gas release aperture while the at least one chemical substance is being retained within the chemical engine; anda conductive gel receptacle in fluid communication with the first working gas release aperture of the chemical engine, the conductive gel receptacle configured to contain conductive gel to be released onto a body of a patient prior to delivering the electrical therapy to the patient, and to release the conductive gel responsive to the release of the working gas.

2. The system of claim 1, further comprising a rupturable seal obstructing the first working gas release aperture that is configured to rupture responsive to pressure applied to the rupturable seal by the working gas.

3. The system of claim 1, wherein the at least one chemical substance comprises a liquid and the chemical substance arrest material is configured to absorb the at least one chemical substance.

4. The system of claim 1, wherein the at least one chemical substance comprises a solid and the chemical substance arrest material includes a filter configured to retain the at least one chemical substance.Docket No. Z2011-7092WO(Z20877WO-01)5. The system of claim 4, wherein the filter is a particle filter.

6. The system of claim 5, wherein the filter is a membrane filter.

7. The system of claim 1, wherein the at least one chemical substance has a non-neutral pH and the chemical substance arrest material includes a neutralization agent configured to neutralize the pH of at least one chemical substance.

8. The system of claim 1, wherein the first chamber comprisesa first compartment; anda second compartment, the first compartment configured to contain the at least one chemical substance, the second compartment configured to contain at least a second chemical substance configured to cause the chemical reaction responsive to contacting the at least one chemical substance.

9. The system of claim 8, wherein the chemical reaction initiator is configured to cause the at least one chemical substance and the second chemical substance to come into contact with one another and generate the working gas.

10. The system of claim 9, wherein the chemical reaction initiator comprises a plunger configured to push the at least one chemical substance from the first compartment into the second compartment.

11. The system of claim 9, wherein at least one of the at least one chemical substance or the second chemical substance is a liquid, and the chemical reaction initiator comprises a syringe configured to releasably house at least one of the at least one chemical substance or the second chemical substance.

12. The system of claim 9, wherein the chemical reaction initiator includes a screw pump.

13. The system of claim 9, wherein the chemical reaction initiator is thermally actuated.Docket No. Z2011-7092WO(Z20877WO-01)14. The system of claim 9, wherein the chemical reaction initiator is mechanically actuated.

15. The system of claim 9, wherein the chemical reaction initiator is electrically actuated.

16. The system of claim 9, wherein the chemical reaction initiator is magnetically actuated.

17. The system of claim 8, further comprising a rupturable barrier between the first compartment and second compartment configured to separate the at least one chemical substance from the second chemical substance prior to an action taken by the chemical reaction initiator.

18. The system of claim 17, wherein the chemical reaction initiator is configured to break the rupturable barrier by applying pressure to one of the at least one chemical substance or the second chemical substance.

19. The system of claim 17, wherein the chemical reaction initiator is configured to break the rupturable barrier by an action performed directly on the rupturable barrier.

20. The system of claim 19, wherein the action performed directly on the rupturable barrier includes mechanically breaking the rupturable barrier.

21. The system of claim 19, wherein the action performed directly on the rupturable barrier includes melting a portion of the rupturable barrier.

22. The system of claim 9, further comprising a barrier removably disposed between the first compartment and the second compartment, the chemical reaction initiator configured to displace the barrier from between the first compartment and the second compartment thereby providing for the at least one chemical substance and the second chemical substance to come into contact with one another and generate the working gas.

23. The system of claim 1, wherein a second working gas release aperture is defined in a wall of the second chamber, the conductive gel receptacle being in fluid communication withDocket No. Z2011-7092WO(Z20877WO-01)the second working gas release aperture, the chemical engine configured to cause the generated working gas to pass through both the first working gas release aperture and the second working gas release aperture.

24. The system of claim 23, wherein the second chamber at least partially surrounds the first chamber.

25. The system of claim 1, wherein the second chamber at least partially surrounds the first chamber.

26. A therapy electrode system for use in delivering electrical therapy, comprising:a chemical engine comprising:a first chamber configured to contain at least two chemical substances, a first working gas release aperture defined in a wall of the first chamber; a second chamber coupled to the first chamber, anda chemical substance arrest material configured to be disposed within the second chamber and to prevent the at least two chemical substances from passing out of the chemical engine, anda chemical reaction initiator configured to initiate generation of a working gas by causing a chemical reaction involving the at least two chemical substances, the first chamber configured to guide the generated working gas through the first working gas release aperture while the at least two chemical substances are retained within the chemical engine; anda conductive gel receptacle in fluid communication with the first working gas release aperture of the chemical engine, the conductive gel receptacle configured to contain conductive gel to be released onto a body of a patient prior to delivering the electrical therapy to the patient, and to release the conductive gel responsive to release of the working gas.

27. The system of claim 26, wherein the at least two chemical substances are retained within the chemical engine at least in part by the chemical substance arrest material.

28. The system of claim 26, wherein the generated working gas is guided by an arrangement of the second chamber while the at least two chemical substances are retained within theDocket No. Z2011-7092WO(Z20877WO-01)chemical engine by a relative arrangement of the first working gas release aperture and the second chamber.

29. The system of claim 26, further comprising a rupturable seal obstructing the first working gas release aperture that is configured to rupture responsive to pressure applied to the rupturable seal by the working gas.

30. The system of claim 26, wherein at least one of the at least two chemical substances comprises a liquid and the chemical substance arrest material is configured to absorb at least one of the at least two chemical substances.

31. The system of claim 26, wherein the chemical substance arrest material includes a filter configured to retain at least one of the at least two chemical substances.

32. The system of claim 31, wherein the filter is a particle filter.

33. The system of claim 32, wherein the filter is a membrane filter.

34. The system of claim 31, wherein the filter is permeable to the working gas but impermeable to liquids.

35. The system of claim 26, wherein at least one of the at least two chemical substances has a non-neutral pH and the chemical substance arrest material includes a neutralization agent configured to neutralize the pH of the at least one of the at least two chemical substances.

36. The system of claim 26, wherein the first chamber includes:a first compartment; anda second compartment, the first compartment configured to contain a first of the at least two chemical substances, the second compartment configured to contain a second of the at least two chemical substances, the second of the at least two chemical substances configured to cause the chemical reaction responsive to contacting the first of the at least two chemical substances.Docket No. Z2011-7092WO(Z20877WO-01)37. The system of claim 36, wherein the chemical reaction initiator is configured to cause the first of the at least two chemical substances and the second of the at least two chemical substances to come into contact with one another and generate the working gas.

38. The system of claim 37, wherein the chemical reaction initiator includes a plunger configured to push the first of the at least two chemical substances from the first compartment into the second compartment.

39. The system of claim 37, wherein at least one of the at least two chemical substances is a liquid, and the chemical reaction initiator includes a syringe configured to releasably house the at least one of the of the at least two chemical substances.

40. The system of claim 37, wherein the chemical reaction initiator includes a screw pump.

41. The system of claim 37, wherein the chemical reaction initiator is thermally actuated.

42. The system of claim 37, wherein the chemical reaction initiator is mechanically actuated.

43. The system of claim 37, wherein the chemical reaction initiator is electrically actuated.

44. The system of claim 37, wherein the chemical reaction initiator is magnetically actuated.

45. The system of claim 36, further comprising a rupturable barrier between the first compartment and second compartment configured to separate the at least two chemical substances from one another prior to an action taken by the chemical reaction initiator.

46. The system of claim 45, wherein the chemical reaction initiator is configured to break the rupturable barrier by applying pressure to one of the at least two chemical substances.Docket No. Z2011-7092WO(Z20877WO-01)47. The system of claim 45, wherein the chemical reaction initiator is configured to break the rupturable barrier by an action performed directly on the rupturable barrier.

48. The system of claim 47, wherein the action performed directly on the rupturable barrier includes mechanically breaking the rupturable barrier.

49. The system of claim 47, wherein the action performed directly on the rupturable barrier includes melting a portion of the rupturable barrier.

50. The system of claim 37, further comprising a barrier removably disposed between the first compartment and the second compartment, the chemical reaction initiator configured to displace the barrier from between the first compartment and the second compartment thereby providing for the at least two chemical substances to come into contact with one another and generate the working gas51. The system of claim 26, wherein a second working gas release aperture is defined in a wall of the second chamber, the conductive gel receptacle being in fluid communication with the second working gas release aperture, the chemical engine configured to cause the generated working gas to pass through both the first working gas release aperture and the second working gas release aperture.

52. The system of claim 51, wherein the second chamber at least partially surrounds the first chamber.

53. The system of claim 26, wherein the second chamber at least partially surrounds the first chamber.

54. The system of claim 26, wherein the at least two chemical substances include at least three chemical substances.Docket No. Z2011-7092WO(Z20877WO-01)55. A therapy electrode system for use in delivering electrical therapy, comprising:a conductive gel deployment chemical engine comprising:a first chamber configured to contain at least one chemical substance, a first working gas release aperture defined in a wall of the first chamber; a second chamber coupled to the first chamber, anda chemical substance arrest material configured to be disposed within the second chamber, the chemical substance arrest material configured to retain the at least one chemical substance thereby preventing the at least one chemical substance from passing out of the chemical engine, andan electric chemical reaction initiator configured toinitiate generation of a working gas by applying an electric current to cause a chemical reaction involving the at least one chemical substance, and initiate release of the working gas out of the first chamber through the first working gas release aperture while the at least one chemical substance is being retained within the chemical engine; anda conductive gel receptacle in fluid communication with the first working gas release aperture of the chemical engine, the conductive gel receptacle configured to contain conductive gel to be released onto a body of a patient prior to delivering the electrical therapy to the patient, and to release the conductive gel responsive to the release of the working gas.

56. The system of claim 55, further comprising a rupturable seal obstructing the first working gas release aperture that is configured to rupture responsive to pressure applied to the rupturable seal by the working gas.

57. The system of claim 55, wherein the at least one chemical substance comprises a liquid and the chemical substance arrest material is configured to absorb the at least one chemical substance.

58. The system of claim 55, wherein the at least one chemical substance comprises a solid and the chemical substance arrest material includes a filter configured to retain the at least one chemical substance.

59. The system of claim 55, wherein the first chamber comprisesa first compartment; andDocket No. Z2011-7092WO(Z20877WO-01)a second compartment, the first compartment configured to contain the at least one chemical substance, the second compartment configured to contain at least a second chemical substance configured to cause the chemical reaction responsive to contacting the at least one chemical substance.

60. The system of claim 59, wherein the electric chemical reaction initiator is configured to apply the electric current to cause the at least one chemical substance and the second chemical substance to come into contact with one another and generate the working gas.

61. The system of claim 55, wherein the electric chemical reaction initiator is configured to apply the electric current to produce heat in response to the electric current.

62. The system of claim 55, wherein the electric chemical reaction initiator is configured to apply the electric current to a heating element.

63. The system of claim 55, wherein the electric chemical reaction initiator is configured to apply the electric current to a resistive wire.

64. The system of claim 63, wherein the resistive wire comprises nickel chromium.

65. The system of claim 63, wherein the electric current is configured to heat the resistive wire to between 150°F and 230°F, or between 230°F and 275°F, or between 275°F and 800°F.

66. The system of claim 63, further comprising an isolating compartment configured to contain at least a second chemical substance, and wherein the resistive wire is configured to melt the isolating compartment or a portion of the isolating compartment thereby releasing the second chemical substance to come into contact with the at least one chemical substance and generate the working gas.

67. The system of claim 66, wherein the isolating compartment or a portion of the isolating compartment is configured to melt at a predetermined melting point.

68. The system of claim 67, wherein the predetermined melting point is between 150°F and 230°F, or between 230°F and 275°F, or between 275°F and 800°F.Docket No. Z2011-7092WO(Z20877WO-01)69. The system of claim 63, further comprising a meltable membrane, and wherein the resistive wire is configured to melt the meltable membrane thereby releasing a second chemical substance to come into contact with the at least one chemical substance and generate the working gas.

70. The system of claim 63, wherein the electric current is configured to heat the resistive wire to between 350°F and 450°F.

71. The system of claim 55, wherein the working gas comprises a pressurized working gas released at between 5 to 100 psi.

72. The system of claim 55, wherein the working gas comprises a pressurized working gas released at between 15 to 35 psi.

73. The system of claim 59, wherein the chemical substance arrest material is configured to absorb one or both of the at least one chemical substance and the second chemical substance.

74. The system of claim 55, wherein the chemical substance arrest material comprises natural sponge, or synthetic sponge, or silica gel particles, or cotton material.

75. The system of claim 55, wherein the chemical substance arrest material comprises a particle filter.

76. The system of claim 55, wherein the chemical substance arrest material comprises a screen.

77. The system of claim 55, wherein the chemical substance arrest material comprises a membrane filter.

78. The system of claim 59, wherein the chemical substance arrest material comprises neutralization agent configured to neutralize a pH of one or both of the at least one chemicalDocket No. Z2011-7092WO(Z20877WO-01)substance and the at least second chemical substance, or a reaction product of the chemical reaction.

79. A therapy electrode system for use in delivering electrical therapy, comprising:a conductive gel deployment chemical engine comprising:a first chamber configured to contain at least one chemical substance, a first working gas release aperture defined in a wall of the first chamber; a second chamber coupled to the first chamber, anda chemical substance arrest material configured to be disposed within the second chamber, the chemical substance arrest material configured to retain the at least one chemical substance thereby preventing the at least one chemical substance from passing out of the chemical engine, anda mechanical chemical reaction initiator configured toinitiate generation of a working gas by mechanically actuating the chemical engine to cause a chemical reaction involving the at least one chemical substance, andinitiate release of the working gas out of the first chamber through the first working gas release aperture while the at least one chemical substance is being retained within the chemical engine; anda conductive gel receptacle in fluid communication with the first working gas release aperture of the chemical engine, the conductive gel receptacle configured to contain conductive gel to be released onto a body of a patient prior to delivering the electrical therapy to the patient, and to release the conductive gel responsive to the release of the working gas.

80. The system of claim 79, further comprising a rupturable seal obstructing the first working gas release aperture that is configured to rupture responsive to pressure applied to the rupturable seal by the working gas.

81. The system of claim 79, wherein the at least one chemical substance comprises a liquid and the chemical substance arrest material is configured to absorb the at least one chemical substance.Docket No. Z2011-7092WO(Z20877WO-01)82. The system of claim 79, wherein the at least one chemical substance comprises a solid and the chemical substance arrest material includes a filter configured to retain the at least one chemical substance.

83. The system of claim 79, wherein the first chamber comprisesa first compartment; anda second compartment, the first compartment configured to contain the at least one chemical substance, the second compartment configured to contain at least a second chemical substance configured to cause the chemical reaction responsive to contacting the at least one chemical substance.

84. The system of claim 83, further comprising a rupturable barrier between the first compartment and second compartment, and wherein the mechanical chemical reaction initiator is configured to mechanically actuate the chemical engine by breaking the rupturable barrier.

85. The system of claim 84, wherein the mechanical chemical reaction initiator is configured to break the rupturable barrier by applying pressure to one of the at least one chemical substance or the second chemical substance.

86. The system of claim 84, wherein the mechanical chemical reaction initiator is configured to break the rupturable barrier by an action performed directly on the rupturable barrier.

87. The system of claim 79, wherein the working gas comprises a pressurized working gas released at between 5 to 100 psi.

88. The system of claim 79, wherein the working gas comprises a pressurized working gas released at between 15 to 35 psi.

89. The system of claim 79, wherein the chemical substance arrest material is configured to absorb one or both of the at least one chemical substance and the at least second chemical substance.Docket No. Z2011-7092WO(Z20877WO-01)90. The system of claim 79, wherein the chemical substance arrest material comprises natural sponge, or synthetic sponge, or silica gel particles, or cotton material.

91. The system of claim 79, wherein the chemical substance arrest material comprises a particle filter.

92. The system of claim 79, wherein the chemical substance arrest material comprises a screen.

93. The system of claim 79, wherein the chemical substance arrest material comprises a membrane filter.

94. The system of claim 79, wherein the chemical substance arrest material comprises neutralization agent configured to neutralize a pH of one or both of the at least one chemical substance and the second chemical substance, or a reaction product of the chemical reaction.

95. The system of claim 83, wherein the mechanical chemical reaction initiator comprises a plunger configured to push the at least one chemical substance from the first compartment into the second compartment.

96. The system of claim 83, wherein at least one of the at least one chemical substance or the second chemical substance is a liquid, and the mechanical chemical reaction initiator comprises a syringe configured to releasably house at least one of the at least one chemical substance or the second chemical substance.

97. The system of claim 83, wherein the mechanical chemical reaction initiator includes a screw pump.

98. The systems of any of claims 1, 26, 55, and 79, wherein the chemical reaction has a peak pressure of between 1 psi and 10 psi.

99. The systems of any of claims 1, 26, 55, and 79, wherein the chemical reaction has a peak pressure of between 10 psi and 20 psi.

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