Battery status determination

Abstract

An example system includes processing circuitry configured to determine a measured current drain from a battery' of an implantable medical device (IMD) during a first period of time in which the IMD is in a first device state. The processing circuitry- is configured to determine an estimated current drain from the battery- of the IMD during a second, period of time in which the IMD is in a second device state. The processing circuitry- is configured to determine, based on the measured current drain and the estimated current drain, a battery- status of the battery of the IMD. The processing circuitry- is configured to generate, for output, information indicative of the battery- status of the battery of the IMD.

Description

Docket No.: A0010170WO01 / 1123-789WO01 BATTERY STATUS DETERMINATION

[0001] This application claims priority to, and the benefit of, U.S. Provisional Application No.63 / 579,704, filed August 30, 2023, and entitled, “BATTERY STATUS DETERMINATION,” the entire contents of which is incorporated herein by reference. TECHNICAL FIELD

[0002] The disclosure relates to batteries of implantable medical devices. BACKGROUND

[0003] Medical devices may be external or implanted and may be used to monitor patient signals such as cardiac activity, biological impedance and to deliver electrical stimulation therapy to patients via various tissue sites to treat a variety of symptoms or conditions such as chronic pain, tremor, Parkinson’s disease, epilepsy, urinary or fecal incontinence, sexual dysfunction, obesity, or gastroparesis and other conditions. In some examples, medical devices may include a rechargeable electrical power source, or may be powered directly by transmitting energy through tissue. SUMMARY

[0004] In general, the disclosure is directed to devices, systems, and techniques for determining a status of a power source, such as a battery, in an implantable medical device (IMD). More particularly, this disclosure is directed to devices, systems, and techniques for using one or more methods of determining the charge used, such as current drain, from the battery of the IMD during different device states of the IMD. This drain of the battery can be used by the system to determine, or estimate, when recharging will be needed.

[0005] In examples described herein, an IMD is configured to deliver therapy and also withhold therapy during one or more time periods. In some examples, during the time periods where the IMD is configured to deliver therapy, a coulomb counter directly measures current drain from the power source. In some examples, where therapy is withheld (e.g., between periods of therapy delivery), one or more components of the IMD, including the coulomb counter, may be disconnected or partially disconnected from the power source of the IMD. Such a state may be referred to herein as a deep sleep state or a reduced power state. The coulomb counter may be disconnected as part of the deviceDocket No.: A0010170WO01 / 1123-789WO01 mode to conserve power usage, but then the coulomb counter cannot be used to monitor battery usage. The IMD may then be configured to determine an estimated current drain during the deep sleep state or reduced power state. The IMD may operate with reduced power consumption during the deep sleep state or reduced power state.

[0006] Together, the IMD or other device may determine the battery status of the IMD using both the measured current drain from the battery from periods where the IMD is configured to deliver therapy and the estimated current drain from periods during the deep sleep state or reduced power state. The battery status may include an indication of at least one of an amount (e.g., a percentage) of remaining charge, a time until recharge, a recharge interval, an expected date of battery depletion, or an expected date of battery recharge. The IMD may be configured to generate information and / or a notification regarding the battery status. The notification regarding the battery status may be provided through a user interface of an external device, from the IMD itself (e.g., a unique stimulation pattern or device vibration), or another suitable method.

[0007] Due to the combination of measured current drain and the estimated current drain for different periods of time and / or different device states, the IMD may provide a relatively accurate determination of battery status while consuming less power during at least some portion of time. This may extend the time period between battery recharges and extend battery life. Because the time between battery recharge may be long (e.g., on the order of days, months, or years, or longer), the use of both measured current drain and estimated current drain (or some other value associated with battery usage) may provide a relatively accurate estimate of the actual battery status for the device and / or user, and may facilitate planning for when recharge is needed. Further, because current drain of the battery of the IMD may vary between different patients (e.g., because of different therapy schedules) and / or devices, a suitably accurate determination of the battery status using this combination of battery usage techniques may better inform a user of the battery status, and facilitate planning for when recharge is needed.

[0008] In one example, a system includes: processing circuitry configured to: determine a measured current drain from a battery of an implantable medical device (IMD) during a first period of time in which the IMD is in a first device state, determine an estimated current drain from the battery of the IMD during a second period of time in which the IMD is in a second device state, determine, based on the measured currentDocket No.: A0010170WO01 / 1123-789WO01 drain and the estimated current drain, a battery status of the battery of the IMD, and generate, for output, information indicative of the battery status of the battery of the IMD.

[0009] In another example, a method includes: determining, by processing circuitry, a measured current drain from a battery of an implantable medical device (IMD) during a first period of time in which the IMD is in a first device state; determining, by the processing circuitry, an estimated current drain from the battery of the IMD during a second period of time in which the IMD is in a second device state; determining, by the processing circuitry, based on the measured current drain and the estimated current drain, a battery status of the battery of the IMD; and generating for output, by the processing circuitry, information indicative of the battery status of the battery of the IMD.

[0010] In another example, a system includes: therapy generation circuitry configured to delivery electrical stimulation therapy via one or more electrodes; an processing circuitry configured to: receive, from a coulomb counter, a measured current drain from a battery of an implantable medical device (IMD) during a first period of time in which the IMD is in a first device state, access information indicative of a characterized current drain from the battery, receive information indicative of IMD events during a second period of time in which the IMD is in a second device state, and calculate, based on the information indicative of the characterized current drain from the battery and on the information indicative of IMD events, an estimated current drain for the second period of time, determine, based on the measured current drain and the estimated current drain, a battery status of the battery of the IMD, and generate, for output, information indicative of the battery status of the battery of the IMD, wherein information indicative of IMD events comprises a duration of the second period of time the IMD was in the second device state as recorded by a timer, and wherein during the second device state, at least the coulomb counter and the therapy generation circuitry are disconnected from the battery.

[0011] The details of one or more examples of the disclosure are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of the disclosure will be apparent from the description and drawings, and from the claims. BRIEF DESCRIPTION OF DRAWINGSDocket No.: A0010170WO01 / 1123-789WO01

[0012] FIG.1 is a conceptual diagram illustrating a leg having a leadless neurostimulation device implanted near a tibial nerve.

[0013] FIG.2 is a block diagram illustrating example components of the implantable medical device of FIG.1.

[0014] FIG.3 is a block diagram of an example external charging device of FIG 1.

[0015] FIG.4 is a block diagram of an example programmer of FIG 1.

[0016] FIG.5 is a graph illustrating current drain during various devices states of an IMD.

[0017] FIG.6A is a conceptual diagram illustrating an example user interface related to a battery according to this disclosure.

[0018] FIG.6B is a conceptual diagram illustrating an example user interface related to a battery according to this disclosure.

[0019] FIG.6C is a conceptual diagram illustrating an example user interface related to a battery according to this disclosure.

[0020] FIG.6D is a conceptual diagram illustrating an example user interface related to a battery according to this disclosure.

[0021] FIG.7 is a flow chart illustrating an example technique for estimating a battery status of a battery.

[0022] Like reference characters denote like elements throughout the description and figures. DETAILED DESCRIPTION

[0023] This disclosure describes devices, systems, and techniques for determining a status of a power source, such as a rechargeable battery in an implantable medical device (IMD). Some devices may measure battery usage during operation using components such as a coulomb counter. The device may then calculate remaining battery capacity using the output from the coulomb counter to then provide an indication regarding battery level or potential battery recharge intervals. However, reliance on measuring the battery usage may require that the device powers the coulomb counter, for example, at all times. The device may then consumer more power than necessary or prevent battery drain data from being generated during low power modes.

[0024] As described herein, a system may be configured to determine the status of the power source of the IMD using one or more methods of determining current drain fromDocket No.: A0010170WO01 / 1123-789WO01 the battery, or other indication of battery usage or remaining power, of the IMD. For example, using multiple methods of determining current drain from the battery of an IMD may reduce the power being used by the IMD while maintaining a suitably accurate determination of remaining charge in the battery. The amount of remaining charge of the battery may be used in determining when recharging of the power source of the IMD is needed.

[0025] In examples described herein, an IMD includes a rechargeable power source (e.g., a battery), and is configured to deliver therapy and also withhold therapy during one or more time periods. The IMD may be configured in a variety of ways to achieve a suitably accurate determination of a status of the power source (e.g., a battery status) to better inform a user of the status of the power source (e.g., how much charge remains, or the duration of usage left in the battery). In some examples, the IMD is configured to measure current drain from the power source during a first period of time in which the IMD is in a first device state (e.g., while the IMD is configured to electrical stimulation therapy). In some examples, the IMD is configured to estimate current drain from the power source for a second period of time during a second device state (e.g., a deep sleep state). The combination of measured current drain and the estimated current drain for different periods of time and / or different device states may enable a suitably accurate determination of battery status while consuming less power.

[0026] The status of the power source (e.g., the battery status) of the IMD may inform a user of when recharging of the power source (e.g., the battery) is needed. In some examples, the IMD is configured to provide information indicative of the status of power source, which may include an indication of at least one of an amount (e.g., a percentage) of remaining charge, a time until recharge, a recharge interval, an expected date of battery depletion, or an expected date of battery recharge. A suitably accurate determination of the battery status may better inform a user of the battery status, and facilitate planning for when recharge is needed.

[0027] Although the devices, systems, and techniques described herein are described primarily in the context of estimating a status of a power source (e.g., a battery status) of IMDs with rechargeable batteries for a tibial nerve stimulator configured to provide tibial nerve stimulation, the techniques described herein may be applicable to other devices configured for other types of therapy. For example, the techniques of this disclosure may be applicable for other types of devices configured for invasive or noninvasiveDocket No.: A0010170WO01 / 1123-789WO01 neuromodulation for pain relief, muscle activation, and / or other therapeutic benefits. Additionally, the techniques of this disclosure are not limited to rechargeable power sources, but are also applicable to other types of power sources (e.g., non-rechargeable power sources, primary cell, etc.).

[0028] FIG.1 is a conceptual diagram illustrating an example system that includes an implantable medical device and an external charging device that charges a rechargeable power source. The example of system 100 in FIG.1 includes an implantable medical device (IMD) 10, an external computing device 108, a programmer 104 (which may be a patient programmer or a clinician programmer), and a server 112. In other examples, the techniques of this disclosure may be implemented in other battery powered devices, for example, an implantable drug pump.

[0029] External computing device 108 includes one or more charging coils, such as external primary coil 26 or internal primary coil 28. External computing device 108 may be used to program or adjust settings of IMD 10 and may also recharge an electrical energy storage device, such as a battery, of IMD 10. External computing device 108 may also communicate with server 112. In other examples, an external device (e.g., programmer 104) separate from external computing device 108 may communicate with IMD 10 to adjust therapy and / or sensing parameters, download recorded data, or perform other functions.

[0030] Server 112 may be one or more servers in a local network or in a cloud computing environment. Server 112 may be configured to communicate with programmer 104, external computing device 108 and / or IMD 10 via wireless communication through a network access point (not shown in FIG.1) and may be co-located with external computing device 108 and / or programmer 104, or may be located elsewhere, such as in a cloud computing data center.

[0031] The example of FIG.1 is a side view of a patient’s leg showing a leadless neurostimulation IMD 10 near the ankle adjacent to the tibial nerve 102. IMD 10 can be implanted through the patient’s skin and cutaneous fat layer via a small incision 101 (e.g., about one to three centimeters (cm)) above the tibial nerve on a medial aspect of the patient’s ankle. While incision 101 is shown approximately horizontal to the length of the tibial nerve, other incisions or implantation techniques could be used according to physician preference. The example of FIG.1 describes a neurostimulation implantable medical device for tibial nerve stimulation. In other examples, the techniques of thisDocket No.: A0010170WO01 / 1123-789WO01 disclosure may apply to other devices, such as implantable neurostimulation system for use in spinal cord stimulation therapy and deep brain stimulation, as well as to other types of medical devices without limitation.

[0032] IMD 10 may be positioned adjacent to the region defined by flexor digitorum longus and soleus in which tibial nerve 102 is contained and implanted adjacent and proximal to a fascia layer. One or more electrodes of IMD 10 may face toward tibial nerve 102. Though not shown in FIG.1, IMD 10 may also connect to one or more leads comprising one or more electrodes (not shown in FIG.1).

[0033] IMD 10 may be constructed of any polymer, metal, or composite material sufficient to house the components of IMD 10. In some examples, IMD 10 is constructed with a biocompatible housing, such as titanium or stainless steel, or a polymeric material such as silicone or polyurethane, and surgically implanted at a site in patient near the tibial nerve. In other examples, IMD 10 is implanted near the pelvis, abdomen, or buttocks. The housing of IMD 10 may be configured to provide a hermetic seal for components, such as a rechargeable power source. In addition, the housing of IMD 10 may be selected of a material that facilitates receiving energy to charge the rechargeable power source.

[0034] Optional testing of neurostimulation IMD 10 may be performed to determine if IMD 10 has been properly positioned in proximity to tibial nerve 102 to elicit a desired response from an applied electrical stimulation. In an example, IMD 10 is controlled by programmer 104 or external computing device 108 to deliver test stimulation, and one or more indicative responses are monitored, such as toe flexion from simulation of the tibial motor neurons controlling the flexor hallucis brevis or flexor digitorum brevis, or a tingling sensation in the heel or sole of the foot excluding the medial arch. If such testing does not elicit appropriate motor or sensory responses, a clinician or other user may reposition IMD 10 and retest.

[0035] Once the clinician or other user has determined IMD 10 is properly positioned to provide an appropriate patient response to delivered stimulation therapy, the housing of device can be secured in place as needed. Securing IMD 10 may be optional as the natural shape of the region in which IMD 10 is implanted, and the shape of IMD 10 itself may have good compatibility with the surrounding tissue thus preventing IMD 10 from shifting or rolling after implantation. In some examples, leadless neurostimulation IMD 10 may further include one or more suture points to help secure IMD 10 to fascia or otherDocket No.: A0010170WO01 / 1123-789WO01 parts of the patient. In some examples, a suture anchor may be included, such as at the distal end of the housing of IMD 10.

[0036] During operation, an electrical stimulation signal may be transmitted between one or more electrodes through the fascia layer. The electrical signal may be used to stimulate tibial nerve 102 which may be useful in the treatment of overactive bladder (OAB) symptoms of urinary urgency, urinary frequency and / or urge incontinence, fecal incontinence, pain or other symptoms.

[0037] In some examples, disease, age, and injury may impair physiological functions of a patient. In one example, bladder dysfunction, such as overactive bladder, urgency, or urinary incontinence, is a problem that may afflict people of all ages, genders, and races. Various muscles, nerves, organs, and conduits within the pelvic floor cooperate to collect, store and release urine. A variety of disorders may compromise urinary tract performance, and contribute to an overactive bladder, urgency, or urinary incontinence that interferes with normal physiological function. System 100 may help relieve some symptoms of some disorders.

[0038] Urinary incontinence may include urge incontinence and stress incontinence. In some examples, urge incontinence may be caused by disorders of peripheral or central nervous systems that control bladder micturition reflexes. Some patients may also suffer from nerve disorders that prevent proper triggering and operation of the bladder, sphincter muscles or nerve disorders that lead to overactive bladder activities or urge incontinence. In some cases, urinary incontinence may be attributed to improper sphincter function, either in the internal urinary sphincter or external urinary sphincter.

[0039] One type of therapy for treating bladder dysfunction includes delivery of electrical stimulation to a target tissue site within a patient to cause a therapeutic effect during delivery of the electrical stimulation. For example, delivery of electrical stimulation from IMD 10 to a target therapy site, e.g., a tissue site that delivers stimulation to modulate activity of a tibial nerve, spinal nerve (e.g., a sacral nerve), a pudendal nerve, dorsal genital nerve, an inferior rectal nerve, a perineal nerve, or branches of any of the aforementioned nerves, may provide a therapeutic effect for bladder dysfunction, such as a desired reduction in frequency of bladder contractions. In some cases, electrical stimulation of the tibial nerve may modulate afferent nerve activities to restore urinary function.Docket No.: A0010170WO01 / 1123-789WO01

[0040] Bladder dysfunction generally refers to a condition of improper functioning of the bladder or urinary tract, and may include, for example, an overactive bladder, urgency, or urinary incontinence. Overactive bladder (OAB) is a patient condition that may include symptoms, such as urgency, with or without urinary incontinence. Urgency is a sudden, compelling urge to urinate, and may often, though not always, be associated with urinary incontinence. Urinary incontinence refers to a condition of involuntary loss of urine, and may include urge incontinence, stress incontinence, or both stress and urge incontinence, which may be referred to as mixed urinary incontinence. As used in this disclosure, the term “urinary incontinence” includes disorders in which urination occurs when not desired, such as stress or urge incontinence. Other bladder dysfunctions may include disorders such as non-obstructive urinary retention.

[0041] In some examples, the techniques described in this disclosure are directed to delivery of neurostimulation therapy in a non-continuous manner which may include on- cycles and off-cycles. For example, an IMD may deliver neurostimulation therapy for a specified period of time followed by a specified period of time when the IMD does not deliver neurostimulation (e.g., withholds delivery of neurostimulation). A period during which stimulation is delivered (an on-cycle) may include on and off periods (e.g., a duty cycle or bursts of pulses) with short inter-pulse durations of time when pulses are not delivered. In some examples, IMD 10 may switch between different operational modes that have different power consumptions for delivery of stimulation and non-delivery of stimulation in order to conserve power when stimulation is not to be delivered.

[0042] The rechargeable power source of IMD 10 may include one or more capacitors, batteries, or other components (e.g., chemical or electrical energy storage devices). Example batteries may include lithium-based batteries, nickel metal-hydride batteries, or other materials. The rechargeable power source may be replenished, refilled, or otherwise capable of increasing the amount of energy stored after energy has been depleted. The energy received from secondary coil 16 may be conditioned and / or transformed by a charging circuit. The charging circuit may then send an electrical signal used to charge the rechargeable power source when the power source is fully depleted or only partially depleted.

[0043] External computing device 108 may be used to recharge the rechargeable power source within IMD 10 implanted in the patient. External computing device 108 may be a hand-held device, a portable device, or a stationary charging system. ExternalDocket No.: A0010170WO01 / 1123-789WO01 computing device 108 may also be referred to as charging device 108 in this disclosure. External computing device 108 may include components necessary to charge IMD 10 through tissue of the patient. External computing device 108 may include an internal primary coil 28 and external primary coil 26. In other examples, external computing device may only include internal primary coil 28 and omit the use of external primary coil 26, or only include external primary coil 26 and omit the use of internal primary coil 28. External computing device 108 may include a housing to enclose operational components such as a processor, memory, user interface, telemetry module, power source, and charging circuit configured to transmit energy to secondary coil 16 via external primary coil 26 and / or internal primary coil 28. Although a user may control the recharging process with a user interface of external computing device 108, external computing device 108 may alternatively be controlled by another device, e.g., programmer 104, a computing device of server 112 such as a tablet computer, laptop or other similar computing device. The second external computing device of server 112 may include a computing device with a touch-screen user interface. In other examples, external computing device 108 may be integrated with an external programmer, such as patient programmer 104, which may be carried by the patient.

[0044] External computing device 108 and IMD 10 may utilize any wireless power transfer techniques that are capable of recharging the power source of IMD 10 when IMD 10 is implanted within the patient. In some examples, system 100 may utilize inductive coupling between internal primary coil 28 and / or external primary coil 26 of external computing device 108 and secondary coils (e.g., secondary coil 16) of IMD 10. In inductive coupling, internal primary coil 28 is placed near implanted IMD 10 such that internal primary coil 28 is aligned with secondary coil 16 of IMD 10. External computing device 108 may then generate an electrical current in internal primary coil 28 based on a selected power level for charging the rechargeable power source of IMD 10. When either internal primary coil 28 or external primary coil 26 are aligned with secondary coil 16, the electrical current in either internal primary coil 28 or external primary coil 26 may magnetically induce an electrical current in secondary coil 16 within IMD 10. Since secondary coil 16 is associated with and electrically coupled to the rechargeable power source, the induced electrical current may be used to increase the voltage, or charge level, of the rechargeable power source. Although inductive coupling is generally describedDocket No.: A0010170WO01 / 1123-789WO01 herein, any type of wireless energy transfer may be used to transfer energy between external computing device 108 and IMD 10.

[0045] External primary coil 26 and / or internal primary coil 28 may include a wound wire (e.g., a coil) (not shown in FIG.1). The coil may be constructed of a wire wound in an in-plane spiral (e.g., a disk-shaped coil). In some examples, this single or even multi- layers spiral of wire may be considered a flexible coil capable of deforming to conform with a non-planar skin surface. The coil may include wires that electrically couple the flexible coil to a power source and a charging module configured to generate an electrical current within the coil. Internal primary coil 28 may be external of the housing of external computing device 108 such that internal primary coil 28 can be placed on the skin of the patient proximal to IMD 10. In some examples, internal primary coil 28 may be disposed on the outside of the housing or even within housing.

[0046] Either external primary coil 26 and / or internal primary coil 28 of system 100 may include a heat sink device (not shown in FIG.1). In the example of system 100, external computing device 108 is the power transmitting unit and IMD 10 is the power receiving unit. IMD 10 may be in a flipped or non-flipped position.

[0047] As noted above, external computing device 108 may also be referred to as recharger 108. Recharger 108 may include a user interface to receive control inputs from a user, such as the patient, medical professional or other caregiver. The user interface of recharger 108 may also provide information to a user. For example, recharger 108 may include a control configured to receive user input (not shown in FIG.1) as well as a set of indicator lights. In some examples the indicator lights may be configured to illuminate the control. The indicator lights may also be configured to output information regarding an operational state of external computing device 108, such as a communication status and wireless power transfer status.

[0048] The processing circuitry determines whether IMD 10 and recharger 108 have established a communication link e.g., via communication circuitry. In response to the processing circuitry determining that recharger 108 and IMD 10 have not established a communication link, the processing circuitry may cause a notification to be generated. Recharger 108 may still wirelessly transfer power to IMD 10, but the notification may signify that recharger 108 is operating in open loop charging mode.

[0049] Processing circuitry of recharger 108 may further determine whether IMD 10 is receiving wireless power. In response to determining that IMD 10 has good powerDocket No.: A0010170WO01 / 1123-789WO01 coupling, such as receiving an amount of wireless power above a power threshold, the processing circuitry may cause a notification to be generated.

[0050] Processing circuitry of system 100, e.g., processing circuitry of recharger 108, processing circuitry of server 112, and / or processing circuitry of IMD 10, may calculate any of the values described herein.

[0051] FIG.2 is a block diagram illustrating example components of the medical device of FIG.1. Implantable medical device (IMD) 210 is an example of IMD 10 described above in relation to FIG.1. In the example illustrated in FIG.2, IMD housing 19 of IMD 210 encloses temperature sensor 39, secondary coil 16, processing circuitry 30, therapy generation and sensing circuitry 34, recharge circuitry 38, memory 32, telemetry circuitry 36, power source 18, switch 33, coulomb counter 35, state control circuitry 31, timer 41, and, in some examples, one or more sensors 37, such as an accelerometer. In other examples, IMD 210 may include a greater or a fewer number of components, e.g., in some examples, IMD 210 may not include temperature sensor 39 or sensors 37. In general, IMD 210 may comprise any suitable arrangement of hardware, alone or in combination with software and / or firmware, to perform the various techniques described herein attributed to IMD 210 and processing circuitry 30, and any equivalents thereof.

[0052] Processing circuitry 30 of IMD 210 may include one or more processors, such as one or more microprocessors, digital signal processors (DSPs), application specific integrated circuits (ASICs), field programmable gate arrays (FPGAs), or any other equivalent integrated or discrete logic circuitry, as well as any combinations of such components. IMD 210 may include a memory 32, such as random access memory (RAM), read only memory (ROM), programmable read only memory (PROM), erasable programmable read only memory (EPROM), electronically erasable programmable read only memory (EEPROM), flash memory, comprising executable instructions for causing the processing circuitry 30 to perform the actions attributed to this circuitry. Moreover, although processing circuitry 30, therapy generation and sensing circuitry 34, recharge circuitry 38, telemetry circuitry 36, temperature sensor 39, state control circuitry 31, coulomb counter 35, switch 33, and timer 41 are described as separate modules, in some examples, some combination of processing circuitry 30, therapy generation and sensing circuitry 34, recharge circuitry 38, telemetry circuitry 36, temperature sensor 39, state control circuitry 31, coulomb counter 35, switch 33, and timer 41 are functionallyDocket No.: A0010170WO01 / 1123-789WO01 integrated. In some examples, processing circuitry 30, therapy generation and sensing circuitry 34, recharge circuitry 38, telemetry circuitry 36, and temperature sensor 39, state control circuitry 31, coulomb counter 35, switch 33, and timer 41 correspond to individual hardware units, such as ASICs, DSPs, FPGAs, or other hardware units. In this disclosure, therapy generation and sensing circuitry 34 may be referred to as therapy generation circuitry 34, for simplicity.

[0053] Memory 32 may store therapy programs or other instructions that specify therapy parameter values for the therapy provided by therapy generation circuitry 34 and IMD 210. In some examples, memory 32 may also store temperature data from temperature sensor 39, instructions for recharging rechargeable power source 18, thresholds, instructions for communication between IMD 210 and an external computing device, or any other instructions required to perform tasks attributed to IMD 210. Memory 32 may be configured to store instructions for communication with and / or controlling one or more temperature sensors of temperature sensor 39. In various examples, memory 32 stores information related to determining the temperature of housing 19 and / or exterior surface(s) of housing 19 of IMD 210 based on temperatures sensed by one or more temperature sensors, such as temperature sensor 39, located within IMD 210.

[0054] For example, memory 32 may store programming settings such as electrical stimulation therapy output magnitude, pulse width, and so on. Memory 32 may determine whether a sensed bioelectrical signal is valid, such as an evoked compound action potential (ECAP) or other signal in response to an output electrical stimulation therapy event. Memory 32 may store programming instructions that when executed by processing circuitry 30 cause processing circuitry 30 to cause therapy generation circuitry 34 to deliver electrical stimulation therapy to a target nerve of a patient.

[0055] Therapy generation and sensing circuitry 34 may generate and deliver electrical stimulation under the control of processing circuitry 30. In some examples, processing circuitry 30 controls therapy generation circuitry 34 by accessing memory 32 to selectively access and load at least one of the therapy programs (e.g., stimulation programs) to therapy generation circuitry 34. For example, in operation, processing circuitry 30 may access memory 32 to load one of the therapy programs (e.g., stimulation programs) to therapy generation circuitry 34. In such examples, relevant stimulation parameters may include a voltage amplitude, a current amplitude, a pulse rate, a pulseDocket No.: A0010170WO01 / 1123-789WO01 width, a duty cycle, or the combination of electrodes 17A, 17B, 17C, and 17D (collectively “electrodes 17”) that therapy generation circuitry 34 may use to deliver the electrical stimulation signal as well as sense biological signals. In other examples, IMD 210 may have more or fewer electrodes than the four shown in the example of FIG.2. In some examples, electrodes 17 may be part of or attached to a housing of IMD 210, e.g., a leadless electrode. In other examples, one or more of electrodes 17 may be part of a lead implanted in or attached to a patient to sense biological signals and / or deliver electrical stimulation, as described above in relation to FIG.1.

[0056] In some examples, one or more electrodes 17 connected to therapy generation circuitry 34 may connect to one or more sensing electrodes, e.g., attached to housing of IMD 210. In some examples, electrodes 17 may be configured to detect the evoked motor response caused by the electrical stimulation therapy event, or other bioelectrical signals such as ECAPs, impedance and so on.

[0057] IMD 210 also includes components to receive power to recharge rechargeable power source 18 when rechargeable power source 18 has been at least partially depleted. As shown in FIG.2, IMD 210 includes secondary coil 16 and recharge circuitry 38 coupled to rechargeable power source 18. Recharge circuitry 38 may be configured to charge rechargeable power source 18 with the selected power level determined by either processing circuitry 30 or an external charging device, such as external computing device 108 described above in relation to FIG.1. Recharge circuitry 38 may include any of a variety of charging and / or control circuitry configured to process or convert current induced in secondary coil 16 into charging current to charge power source 18.

[0058] Secondary coil 16 may include a coil of wire or other device capable of inductive coupling with a primary coil disposed external to a patient. Although secondary coil 16 is illustrated as a simple loop of in FIG.2, secondary coil 16 may include multiple turns of conductive wire. Secondary coil 16 may include a winding of wire configured such that an electrical current can be induced within secondary coil 16 from a magnetic field. The induced electrical current may then be used to recharge rechargeable power source 18.

[0059] Recharge circuitry 38 may include one or more circuits that process, filter, convert and / or transform the electrical signal induced in the secondary coil to an electrical signal capable of recharging rechargeable power source 18. For example, in alternating current induction, recharge circuitry 38 may include a half-wave rectifier circuit and / or aDocket No.: A0010170WO01 / 1123-789WO01 full-wave rectifier circuit configured to convert alternating current from the induction to a direct current for rechargeable power source 18. The full-wave rectifier circuit may be more efficient at converting the induced energy for rechargeable power source 18. However, a half-wave rectifier circuit may be used to store energy in rechargeable power source 18 at a slower rate. In some examples, recharge circuitry 38 may include both a full-wave rectifier circuit and a half-wave rectifier circuit such that recharge circuitry 38 may switch between each circuit to control the charging rate of rechargeable power source 18 and temperature of IMD 210.

[0060] Rechargeable power source 18 may include one or more capacitors, batteries, and / or other energy storage devices. Rechargeable power source 18 may deliver operating power to the components of IMD 210. In some examples, rechargeable power source 18 may include a power generation circuit to produce the operating power. Rechargeable power source 18 may be configured to operate through many discharge and recharge cycles. Rechargeable power source 18 may also be configured to provide operational power to IMD 210 during the recharge process. In some examples, rechargeable power source 18 may be constructed with materials to reduce the amount of heat generated during charging. In other examples, IMD 210 may be constructed of materials and / or using structures that may help dissipate generated heat at rechargeable power source 18, recharge circuitry 38, and / or secondary coil 16 over a larger surface area of the housing of IMD 210. In some examples, power source 18 includes a non-rechargeable power source.

[0061] Although rechargeable power source 18, recharge circuitry 38, and secondary coil 16 are shown as contained within the housing of IMD 210, in alternative implementations, at least one of these components may be disposed outside of the housing. For example, in some implementations, secondary coil 16 may be disposed outside of the housing of IMD 210 to facilitate better coupling between secondary coil 16 and the primary coil of external charging device. In other examples, power source 18 may be a primary power cell and IMD 210 may not include recharge circuitry 38 and secondary coil 16.

[0062] Processing circuitry 30 may also control the exchange of information with an external computing device using telemetry circuitry 36. Telemetry circuitry 36 may be configured for wireless communication using radio frequency (RF) protocols, such as Bluetooth, including Bluetooth low energy (BLE), or similar RF protocols, as well as using inductive communication protocols. Telemetry circuitry 36 may include one orDocket No.: A0010170WO01 / 1123-789WO01 more antennas configured to communicate with an external charging device (e.g., external computing device 108 of FIG.1). Processing circuitry 30 may transmit operational information and receive therapy programs or therapy parameter adjustments via telemetry circuitry 36. Also, in some examples, IMD 210 may communicate with other implanted devices, such as stimulators, control devices, or sensors, via telemetry circuitry 36. In addition, telemetry circuitry 36 may be configured to control the exchange of information related to sensed and / or determined temperature data, for example temperatures sensed by and / or determined from temperatures sensed using temperature sensor 39. In some examples, telemetry circuitry 36 may communicate using inductive communication, and in other examples, telemetry circuitry 36 may communicate using RF frequencies separate from the frequencies used for inductive charging.

[0063] In some examples, processing circuitry 30 may transmit, via control of telemetry circuitry 36, additional information to external charging device related to the operation of rechargeable power source 18. For example, processing circuitry 30 may control telemetry circuitry 36 to transmit indications that rechargeable power source 18 is completely charged, rechargeable power source 18 is fully discharged, the amount of charging current output by recharge circuitry 38 e.g., to power source 18, or any other charge status of rechargeable power source 18. In some examples, processing circuitry 30 may use telemetry circuitry 36 to transmit instructions to external charging device, including instructions regarding further control of the charging session, for example instructions to lower the power level or to terminate the charging session, based on the determined temperature of IMD housing 19.

[0064] Processing circuitry 30 may also transmit information to external charging device that indicates any problems or errors with rechargeable power source 18 that may prevent rechargeable power source 18 from providing operational power to the components of IMD 210. In various examples, processing circuitry 30 may receive, through telemetry circuitry 36, instructions for algorithms, including formulas and / or values for constants to be used in the formulas, that may be used to determine the temperature of the housing 19 and / or exterior surface(s) of housing 19 of IMD 210 based on temperatures sensed by temperature sensor 39 located within IMD 210 during and after a recharging session performed on rechargeable power source 18.

[0065] IMD 210 also includes components for determining a status of power source 18. For example, in examples where power source 18 includes a battery, IMD 210 mayDocket No.: A0010170WO01 / 1123-789WO01 include components for determining (e.g., measuring, estimating, receiving, etc.) information related to a battery status or battery charge or activity (e.g., an amount of current drain from the battery, an amount of charge remaining in the battery, etc.). Components of IMD 210 for determining information related to the battery status include coulomb counter 35, switch 33, timer 41, and state control circuitry 31. Coulomb counter 35, switch 33, timer 41, and state control circuitry 31 may be used alone and / or in connection with other components of IMD 210, including processing circuitry 30.

[0066] In some examples, IMD 210 is configured to transition between different operational states. For example, processing circuitry 30 and / or state control circuitry 31 are configured to transition IMD 210 between different operational states where different components of IMD 210 are powered and operational. In a first device state (e.g., a therapy state or operational state) and / or during a first period of time, IMD 210 may be configured to deliver electrical stimulation therapy. Specifically, in the first device state, IMD 210 may be actually delivering therapy, or the components needed for IMD 210 to deliver therapy are receiving power but not actually delivering therapy (e.g., a device “standby” state). In a second device state, therapy is withheld or otherwise not scheduled, and IMD 210 may have one or more components disconnected or partially disconnected from power source 18 or otherwise in a state for consuming less power (e.g., a deep sleep state, a reduced power state, etc.). Processing circuitry 30 and / or state control circuitry 31 may also be configured to determine whether IMD 210 is in a given operational states. For example, processing circuitry 30 and / or state control circuitry 31 are configured to perform certain functions depending on whether IMD 210 is in a particular operational state (e.g., the first device state or the second devices state).

[0067] In some examples, IMD 210 uses one or more methods or combinations of components to determine the status of power source 18 of IMD 210 during different operational states. Using multiple methods of determining the status of power source 18 may optimize power loss from power source 18 while still maintaining a reliable determination of the status of power source 18.

[0068] In some examples, coulomb counter 35 is be configured to measure current drain from power source 18 (e.g., a battery) of IMD 210. Coulomb counter 35 may be configured to measure current drain during at least a first period of time in which the IMD is in a first device state (e.g., while the IMD is delivering electrical stimulation therapy via electrodes 17 or at least powered “on” and configured to delivery electricalDocket No.: A0010170WO01 / 1123-789WO01 stimulation therapy such as the “standby” state mentioned above). In some examples, coulomb counter 35 measures current drain directly from power source 18 (e.g., a battery) of IMD 210 during the first period of time. Coulomb counter 35 may output real-time current measurements that processing circuitry 30 uses to calculate a cumulative current used during a period of this may be part of or equal to the first period of time. In other examples, coulomb counter 35 may output an average current and / or cumulative current over a period of time to processing circuitry 30 for determining the current drain during the first period of time. Because coulomb counter 35 directly measures current drain from power source 18 (e.g., a battery), the measured current may be more accurate as compared to other methods of determining current drain (e.g., methods involving indirect measurement and / or estimation of current drain). Processing circuitry 30 may be configured to receive the measured current drain, or one or more values indicative of the measure current drain, from coulomb counter 35.

[0069] In some examples, IMD 210 is configured to deliver electrical stimulation therapy according to one or more therapy programs (e.g., stimulation programs). In some examples, therapy programs include unique therapy parameters (e.g., duration, amplitude, frequency, and / or pulse width) for each therapy program. In some examples in which IMD 210 delivers electrical stimulation at different times with more than one therapy program (e.g., at least a first therapy program and a second therapy program), processing circuitry 30 is configured to receive and / or store values associated with current drain for multiple instances of therapy delivery in which each instances of therapy delivery can be associated with a different therapy program (e.g., at least a first therapy program and a second therapy program).

[0070] In some examples, processing circuitry 30 is configured to determine the current drain from power source 18 by using, or at least partially using, one or more stored values (e.g., via a lookup table). For example, processing circuitry 30 may be configured to access (via memory 32, programmer 104, or server 112 etc.) one or more stored values related to or indicative of the measured current drain during at least a first period of time in which the IMD is in a first device state (e.g., while the IMD is delivering electrical stimulation therapy via electrodes 17 or at least powered “on” and configured to delivery electrical stimulation therapy such as the “standby” state mentioned above). In some examples, the stored values related to or indicative of the measured current drain may enable IMD 210, via processing circuitry 30, to confirm orDocket No.: A0010170WO01 / 1123-789WO01 supplement the measured current drain via coulomb counter 35. A hybrid approach may include using measured values of current drain in combination with stored values. Values for determining current drain for the first period of time in which IMD 210 is in the first device state may include one or more of a stimulation amplitude, duration, pulse width, and / or other relevant parameters. In this manner, processing circuitry 30 may be configured to use the measured current drain at certain times and / or known stimulation output and the stored values to calculate current drain for IMD 210 during the first device state.

[0071] As another example, IMD 210 may additionally or alternatively use more energy-efficient methods for estimating a battery status during a second period of time in which IMD 210 is in a second devices state (e.g., a deep sleep state). In some examples, high-power circuitry or components of IMD 210 may be disconnected from power source during the second device state, which may include one or more of a deep sleep state or a reduced power state. For example, state control circuitry 31 may be configured to disconnect coulomb counter 35 from power source 18 (e.g., the battery) via switch 33 (e.g., a circuitry switch). State control circuitry 31 may, in some examples, disconnect coulomb counter 35 from power source 18 by opening switch 33. In this way, IMD 210 may be able to conserve power during the second devices state because certain electrical components, including coulomb counter 35, are disconnected from power source 18. However, disconnecting coulomb counter 35 from power source 18 also disables coulomb counter 35 from directly measuring current drain during the second devices state (e.g., a deep sleep state). In some examples, it should be noted that coulomb counter 35 may be connected in order to measure current drain from power source 18 during at least a portion of the second devices state (e.g., a deep sleep state). Processing circuitry 30 may control state control circuity 31 to operate switch 33, or processing circuitry 30 may directly control switch 33 in other examples.

[0072] In some examples, one or more components of IMD 210 (e.g., processing circuitry 30, alone in combination with other components) may be configured to estimate current drain from power source 18 (e.g., battery) of IMD 210 for a second period of time during the second device state. As discussed above, this second period of time may include the coulomb counter 35 being disconnected and not available to measure the current drain from power source 18. For example, where a coulomb counter 35 does not measure current drain from power source 18, one or more techniques may be used toDocket No.: A0010170WO01 / 1123-789WO01 estimate the current drain from power source 18. In some examples, processing circuitry 30, alone or in combination with other components, are configured to determine (e.g., calculate) an estimated current drain based on at least information indicative of a characterized current drain and information indicative of IMD 210 events. The information indicative of the characterized current drain, as well as information indicative of IMD 210 events, may enable IMD 210 to estimate (e.g., via a calculation) current drain from power source 18 (e.g., battery) during the second devices state (e.g., a deep sleep state). For example, the information indicative of the characterized current drain includes an amount of current drain per unit of time (e.g., amperes per hour), such that processing circuitry 30 determines current drain during the second devices state (e.g., a deep sleep state) based on the amount of time spent in the second device state and this expected, or estimated, current drain or other indication of battery usage. In some examples, processing circuitry 30 accesses information indicative of the characterized current drain from memory 32, programmer 104, server 112, or another suitable component. Processing circuitry 30 may be configured to receive information indicative of IMD 210 events from timer 41. To determine the estimated current drain during the second device state, processing circuitry 30 may be configured to access a lookup table, wherein the lookup table correlates at least the information indicative of IMD 210 events and the information indicative of the characterized current drain from power source 18.

[0073] In some examples, the information indicative of the characterized current drain used to estimate the status of power source 18 includes one or more stored values (e.g., stored in memory 32, or available via a lookup table). For example, a characterized current drain of IMD 210 during a the second devices state (e.g., a deep sleep state) may be determined prior to implant in a patient (e.g., during manufacturing), and stored for later use and / or retrieval. The characterized current drain may indicate an amount of current drain per period of time while IMD 210 is the second devices state (e.g., a deep sleep state). In some examples, the characterized current drain during the second devices state (e.g., a deep sleep state) is not device specific. For example, the characterized current drain may be the same value and / or calculation (e.g., an average or mean) for a given model of stimulator, and not otherwise be tested for a given device. Information indicative of the characterized current drain may include information from multiple devices (e.g., multiple implanted devices in multiple different patients). In other examples, the characterized current drain during the second devices state (e.g., a deepDocket No.: A0010170WO01 / 1123-789WO01 sleep state) includes at least some device-specific component. For example, a current drain during the second devices state (e.g., a deep sleep state) is measured for each device to serve at least in part as the characterized current drain. As another example, a current drain during the second devices state (e.g., a deep sleep state) is measured for a given device prior to implant to serve at least in part as the characterized current drain for a group and / or batch of devices. In some examples, the characterized current drain parameters are not updated (e.g., not updated after implant in a patient). However, in other examples, the characterized current drain may be updated (e.g., based on user input, or dynamically). For example, the calculation of the estimated current drain based on the characterized current drain during the second devices state (e.g., a deep sleep state) may dynamically change based on actually measured voltage and / or current of power source 18. In some examples, the calculation of the estimated current drain based on the characterized current drain may dynamically change as a function of the overall capacity of power source 18, if the overall capacity of power source 18 changes over time.

[0074] In some examples, timer 41 is configured to provide information indicative of IMD 210 events, which may facilitate and / or enable determination of an estimated current drain during the second devices state (e.g., a deep sleep state). In some examples, timer 41 includes a real-time clock. In examples where timer 41 includes a real time clock, timer 41 may be configured to provide processing circuitry 30, and processing circuitry 30 may be configured to receive, one or more timestamps. The one or more timestamps may indicate when IMD 210 transitions between device states (e.g., between the first device state and the second devices state). Additionally or alternatively, timer 41 includes an oscillator, wherein timer 41 may be configured to provide to processing circuitry 30, a number (e.g., a count) of oscillations. Processing circuitry 30 may be configured to receive, from timer 41, the number of oscillations and calculate a time period based on the number of oscillations. In some examples, timer 41 includes an oscillator and a counter, wherein timer 41 is configured to calculate one or more durations of time based on a number of oscillations counted by the counter.

[0075] Timer 41 may remain powered and operational during at least the second devices state (e.g., a deep sleep state), but may also remain operation during the first device state (e.g., when IMD 210 is configured to deliver therapy). In some examples, timer 41 records the duration of time IMD 210 is in the second devices state (e.g., a deep sleep state). Additionally, or alternatively, timer 41 records when IMD 210 transitionsDocket No.: A0010170WO01 / 1123-789WO01 between the first device state (e.g., when IMD 210 is configured to deliver therapy) and the second devices state (e.g., a deep sleep state) and vice versa. For example, timer 41 records one or more timestamps of at least one of IMD 210 entering or exiting the second device state. In this way, timer 41 may provide a processor, such as processing circuitry 30, with timestamps of when IMD 210 transitions between the first device state (e.g., when IMD 210 is configured to deliver therapy) and the second devices state (e.g., a deep sleep state), which may enable processing circuitry 30 to determine (e.g., calculate) the duration of time spent in the first device state or the second device.

[0076] Although timer 41 provides information indicative of IMD 210 events in the example of FIG.2, another suitable component may provide information indicative of IMD 210 events. For example, an external device (e.g., external computing device 108, programmer 104, and / or server 112 of FIG.1) to IMD 210 may record information indicative of IMD 210 events. For example, external computing device 108, programmer 104, and / or server 112 records the duration of time IMD 210 is in the second devices state (e.g., a deep sleep state). The external device (e.g., external computing device 108, programmer 104, and / or server 112 of FIG.1) may be configured to send the information indicative of IMD 210 events to IMD 210.

[0077] In addition, or alternative, to the methods of determining a current drain from power source 18 and / or a status of power source 18 noted above, IMD 210, via processing circuitry 30, may be configured to measure a voltage of power source 18 (e.g., a battery) as part of determining the battery status or battery usages. For example, to determine an estimated current drain from power source 18 (in addition to or as an alternative to the methods noted above), processing circuitry 30 may be configured to measure a voltage of power source 18 during at least one of the first device state (e.g., when IMD 210 is configured to deliver therapy) and the second devices state (e.g., a deep sleep state). The measured voltage may be an alternate way to determine a status of power source 18, or may supplement any of the methods describe above for determining a status of power source 18. For example, IMD 210, via processing circuitry 30, may be configured to measure the voltage of power source 18 (e.g., a battery) upon transitioning between the first device state (e.g., when IMD 210 is configured to deliver therapy) and the second devices state (e.g., a deep sleep state) and vice versa. In some examples, IMD 210 may only use a measured voltage for determining a current drain from power source 18 and / or a status of power source 18 during the beginning of the battery and / or deviceDocket No.: A0010170WO01 / 1123-789WO01 life and / or during the end of the battery and / or device life (e.g., where the voltage curve is not flat).

[0078] While this disclosure primarily describes IMD 210 as configured to operate in at least one of the first device state (e.g., when IMD 210 is configured to deliver therapy) and the second devices state (e.g., a deep sleep state), it is understood that IMD 210 can be configured to operate in additional and / or alternative devices states. In some examples, IMD 210 includes multiple device states in which IMD 210 is configured to deliver therapy (e.g., a first device state in which IMD 210 is configured to deliver therapy according to a first therapy program and a third device state in which IMD 210 is configured to deliver therapy according to a second therapy program different from the first therapy program). Processing circuitry 30 can be configured to determine a current drain from power source 18 and / or a status of power source 18 for any or all of the operational states of IMD 210 (e.g., which can include one, two, three, four, five or more device states, which can each include associated periods of time). In some examples, processing circuitry 30 is configured to determine a measured current drain from power source 18 for a first instance (e.g., first period of time) of therapy delivery and a second instance (e.g., second period of time) of therapy delivery, wherein the first instance of therapy delivery is associated with a first therapy program having a first set of therapy parameters (e.g., a first therapy program) and the second instance of therapy delivery is associated with a second set of therapy parameters (e.g., a second therapy program) different from the second set of therapy parameters. In some examples, the second instance of therapy delivery can be associated with a third period of time where a second period of time is associated with a relatively lower power device state (e.g., deep sleep state as discussed in this disclosure). In some examples, processing circuitry 30 is configured to determine an aggregate measured current drain based on at least a first measured current drain associated with therapy delivery according to a first therapy program (e.g., a first set of therapy parameters) and a second measured current drain associated with therapy delivery according to a second therapy program (e.g., having a second set of therapy parameters different from the first set of therapy parameters). Further, processing circuitry 30 can be configured to determine measured current drain for any number of instances of therapy delivery associated with a unique set of therapy parameters (e.g., unique therapy programs).Docket No.: A0010170WO01 / 1123-789WO01

[0079] In some examples, state control circuitry 31 is configured to remove, or prevent, power normally provided by power source 18 from various components of IMD 210. In some examples, processing circuitry 30 is configured to determine whether IMD 210 is in the first device state (e.g., when IMD 210 is configured to deliver therapy) or the second devices state (e.g., a deep sleep state) and vice versa. In response to determining IMD 210 is in the first device state and / or the second device state, IMD 210, via processing circuitry 30, may be configured to cause state control circuitry 31 and / or switch 33 to perform operations. For example, state control circuitry 31 may be configured to remove and / or partially remove power from one or more of processing circuitry 30, therapy generation and sensing circuitry 34, and / or coulomb counter 35, as well as other components of IMD 210, when IMD 210 transitions to and / or is in the second devices state (e.g., a deep sleep state). State control circuitry 31 may also be configured to restore power to such components upon exiting the second devices state. Switch 33 may be configured to, when IMD 210 transitions to and / or is in the second devices state (e.g., a deep sleep state), prevent power from power source 18 from powering components of IMD 210 (e.g., processing circuitry 30, therapy generation and sensing circuitry 34, and / or coulomb counter 35, as well as other components of IMD 210). For example, during the second device state, state control circuitry 31 and / or processing circuitry 30 may control switch 33 to open such that at least coulomb counter 35 and / or therapy generation circuitry 34 are disconnected from power source 18 (e.g., a battery). Although not shown in the example of FIG.2, coulomb counter 35 may be positioned between power source 18 and any electrical components operable in the first device state or to otherwise measure the current flowing to these electrical components.

[0080] IMD 210, via processing circuitry 30, may be configured to determine a status of power source 18 (e.g., a battery status, in examples where power source 18 includes at least a battery). The determination of the status of power source 18 (e.g., a battery status) may be based on the measured current drain and the estimated current drain of the battery of the IMD for different respective periods of time. For example, processing circuitry 30, is configured to determine a current drain from power source 18 based on and / or include the aggregate of at least the measured current drain from power source 18 during the first device state (e.g., when IMD 210 is configured to deliver therapy) and the estimated current drain during the second device state (e.g., a deep sleep state). Processing circuitry 30 may be configured to determine or update a status of power source 18 constantly or atDocket No.: A0010170WO01 / 1123-789WO01 one or more intervals (e.g., periodically). For example, processing circuitry 30 may be configured to automatically update (e.g., without a user prompt) the status of power source 18 (e.g., battery status) in response to IMD 210 exiting the second device state (e.g., a deep sleep state). Processing circuitry 30 may be configured to not update the status of power source 18 while in the second device state. In this way, because a low amount of charge may be lost during the second device state (e.g., a deep sleep state), IMD 210 may further conserve power by not directly measuring the status of power source 18 while in the second device state, such as via a coulomb counter. The determined status of power source 18 may be provided to the user (e.g., a patient or clinician). Because the time between battery recharge may be long (e.g., on the order of days, months, or years, or longer), a suitably accurate determination of battery status may better inform a user of the battery status, and facilitate planning for when recharge is needed.

[0081] Processing circuitry 30 may also be configured to determine the status of power source 18 and / or generate information indicative of the status of power source 18 based, at least in part, on recharge session information. A recharge session may include a period of time where power source 18 is connected to a recharging device (e.g., external charging device 208 of FIG.3) and / or otherwise recharging power source 18. For example, processing circuitry 30 may be configured to update the status of power source 18 based on information related to a recharge session (e.g., amount of time spent in a recharge session or amount of charge gained during a recharge session). In some examples, processing circuitry 30 is configured to update the status of power source 18 based at least partly on the amount of time spent in a recharge session, and / or the amount of charge gained during a recharge session. For example, an estimated date of charge depletion or date of next recharge may be updated to a date farther in the future after a recharge session. Memory 32 may be configured to store the information related to the recharge session (e.g., amount of time spent in a recharge session or amount of charge gained during a recharge session). Additionally, or alternatively, information related to the recharge session may be stored in another external device (e.g., external computing device 108, programmer 104, or server 112, as shown in FIG.1).

[0082] In some examples, IMD 210, via processing circuitry 30, may be configured to perform diagnostic operations related to power source 18. For example, processing circuitry 30 may compare the determined status of power source 18 (e.g., an amount ofDocket No.: A0010170WO01 / 1123-789WO01 current drain from the battery, an amount of charge remaining in the battery, etc.) against an expected value (e.g., a threshold and / or another value). The diagnostic operations, including the comparison of the determined status of power source 18 against the expected value, may indicate and / or confirm an accuracy of the determination of the determined status of power source 18. In some examples, the diagnostic operations may indicate and / or confirm an accuracy of the estimated current drain from power source 18 (e.g., battery) of IMD 210 for the second period of time during the second device state, which may include one or more of a deep sleep state or reduced power state. IMD 210 may perform the diagnostic operations when IMD 210 transitions between the first device state (e.g., when IMD 210 is configured to deliver therapy) and the second devices state (e.g., a deep sleep state) and vice versa. IMD 210 may be configured to store information (e.g., diagnostic information) related to diagnostic operations (e.g., in an event log). IMD 210 may be configured to provide an alert, notification, and / or other stored information (e.g., via an event log) related to the diagnostic operations.

[0083] IMD 210, via processing circuitry 30, may be configured to generate, for output, information indicative of the status of power source 18 (e.g., a battery status, in examples where power source 18 includes at least a battery). Information indicative of the status of power source 18 (e.g., a battery status) may include an indication of at least one of an amount (e.g., a percentage) of remaining charge, a time until recharge, a recharge interval, a date of charge depletion, an expected date of battery depletion, or an expected date of battery recharge. In some examples, IMD 210, via processing circuitry 30, may be configured generate for output information indicative of the status of power source 18 at pre-determined events (e.g., battery percentage thresholds of remaining charge, such as 20 percent, 10 percent, etc.). The information indicative of the status of power source 18 may be updated automatically on a periodic basis, after one or more events (e.g., a recharge session, the start or end of a therapy session, etc.), or upon interrogation of IMD 210 by an external device (e.g., programmer 104, external computing device 108, or server 112).

[0084] Information indicative of the status of power source 18 (e.g., a battery status) may be generated from a model using one or more inputs. For example, a processing circuitry 30 may predict or estimate a recharge interval based on a model. In some examples, information indicative of the status of power source 18 incorporates information of past use or predicted future use of IMD 210. For example, IMD 210 mayDocket No.: A0010170WO01 / 1123-789WO01 be configured to access one or more therapy schedules or other predicted future use to determine (e.g., estimate or predict) the status of power source 18. In this way, IMD 210 may also use past current drain (e.g., measured or estimated) as well as expected future current drain (e.g., from a therapy schedule) to indicate a time until recharge is needed, a recharge interval, a date of charge depletion, an expected date of battery depletion, or an expected date of when battery recharge is needed. As discussed previously, IMD 210 may be configured to use recharge session information (e.g., amount of time spent in a recharge session or amount of charge gained during a recharge session) to generate information indicative of the status of power source 18.

[0085] In some examples, notifications regarding the status of power source 18 may inform a user of information indicative of the status of power source 18 (e.g., a battery status). For example, processing circuitry 30 may be configured to generate a notification when a charge of power source 18 drops below a predefined threshold, or when another user defined event has occurred. For example, a user may specify a time threshold since the last recharge session to cause processing circuitry 30 to provide a notification or prompt to recharge power source 18 after the time threshold has elapsed. Similarly, a user may specify a maximum recharge time to cause processing circuitry 30 to provide a notification or prompt to recharge once the time needed to recharge power source 18 reaches the user-specified maximum recharge time.

[0086] In some examples, processing circuitry 30 is configured to generate one or more of a visual, audio, tactile, haptic feedback, or related notification regarding the status of power source 18. Processing circuitry 30 may be configured to output a notification or information regarding the status of power source 18 via programmer 104 or external computing device 108 (e.g., via user interface 54 of external charging device 208 or via user interface 86 of programmer 204, shown in FIG.3 and FIG.4 respectively). In some examples, a notification or information regarding the status of power source 18 includes an estimated date of charge depletion and or an amount of time remaining until the charge level of power source 18 is depleted and / or depleted below a level needed for proper functioning of IMD 210. In some examples, a notification or information regarding the status of power source 18 includes one or more prompts (e.g., one-time, or at an interval) to a user to recharge power source 18. Processing circuitry 30 may be configured to provide a haptic feedback notification (e.g., a vibration) via IMD 210 while implanted in a patient to alert the patient of the status of power source 18. ForDocket No.: A0010170WO01 / 1123-789WO01 example, processing circuitry 30 may be configured to cause IMD 210 to vibrate in a predetermined pattern of pulses to alert a patient of a low level of charge, prompt recharging, or provide other information related to the status of power source 18 (e.g., the battery). IMD 210 may vibrate before or after a stimulation session, or periodically (e.g., daily) to provide a notification related to the status of power source 18. Processing circuitry 30 may be configured to cause a IMD 210 to output a stimulation-based notification (e.g., a unique stimulation profile via electrodes 17 or stimulation at the subcutaneous pocket containing the housing of IMD 210) to alert the patient of the status of power source 18. For example, processing circuitry 30 may be configured to cause IMD 210 to generate a unique predetermined stimulation pattern to alert a patient of a low level of charge, prompt recharging, provide other information related to the status of power source 18 (e.g., the battery). In some examples, processing circuitry 30 may be configured to alert a patient, clinician, or other user of the status of power source 18 via programmer 104 (in examples where programmer 104 includes a clinician programmer), via external computing device 108, via server 112, and / or via another suitable method. Visual alerts may include where a light source on IMD 210 (e.g., a light-emitting diode (LED)) emits light to provide a notification related to the status of power source 18. Alerts regarding the status of power source 18 to a patient, clinician, or other user may additionally or alternatively include one or more of a text-message, automated phone call, email, or notification through a mobile-device application.

[0087] In examples where a stimulation-based notification (e.g., a unique stimulation pattern) is used to inform a user of the status of power source 18, one or more parameters may be configured by the clinician and / or the patient. The unique stimulation pattern may include intervals of stimulation, increasing or decreasing rates of pulses, or varying amplitudes of stimulation. As an example, processing circuitry 30 may be configured to cause IMD 210 to provide a stimulation pattern of 1 second on, 2 seconds off, then 1 second on, 1 second off, then 1 second on, 0.5 seconds off, followed by a ramp down after the scheduled therapy session is delivered. A patient may be trained to the unique stimulation pattern, or another source of information (e.g., a device label, or user interface) may inform a patient to be aware of the unique stimulation pattern (e.g., such as for recharging power source 18). In some examples, the clinician and / or the patient sets a perception threshold for a recharge reminder. In some examples, the clinician and / or patient can select whether and / or when the stimulation-based notification is given. ForDocket No.: A0010170WO01 / 1123-789WO01 example, the clinician and / or patient may set the stimulation-based notification to occur before or after a stimulation session, or at another time. As another example, the clinician and / or patient may set the stimulation-based notification to occur on a unique schedule. Besides informing the user of the status of power source 18, a unique stimulation-based notification may be used to alert the patient to perform another task (e.g., open a device application, check the status of IMD 210, recharge power source 18, etc.).

[0088] FIG.3 is a block diagram of an example an external computing device of FIG. 1. External charging device 208 in of FIG.3 is an example of external computing device 108 described above in relation to FIG.1. In some examples, external charging device 208 may be described as a hand-held device, in other examples, external charging device 208 may be a larger or a non-portable device. In addition, in other examples, external charging device 208 may be included as part of an external programmer or include functionality of an external programmer. As shown in the example of FIG.3, external charging device 208 includes a housing 24 connected to a charging head 226. Housing 24 encloses components such as a primary processing circuitry 50, memory 52, user interface 54, telemetry circuitry 56, control 62, one or more sets of indicator lights 64, audio output circuitry 70, haptic output circuitry 72 and power source 60. Charging head 226 may include charging circuitry 58, temperature sensor 59, and external primary coil 48. Charging head 226 and / or external primary coil 48 may be an example of external primary coil 26 as shown in FIG.1. Housing 24 is electrically coupled to charging head 226 via a cable. Housing 24 may also include charging circuitry 68 and internal primary coil 228, which is an example of internal primary coil 28 described above in relation to FIG.1.

[0089] In some examples, separate charging head 226 may facilitate positioning of external primary coil 48 over secondary coil 16 of IMD 10 (as shown in FIG. 1) or IMD 210 (as shown in FIG.2). In some examples, charging circuitry 68 and / or internal primary coil 228 may be integrated within housing 24. In other examples, external charging device 208 may not include charging head 226. Memory 52 may store instructions that, when executed by primary processing circuitry 50, causes primary processing circuitry 50 and external charging device 208 to provide the functionality ascribed to external charging device 208 throughout this disclosure, and / or any equivalents thereof. External primary coil 48 and internal primary coil 228 may also be referred to as an antenna. In some examples, external charging device 208 may includeDocket No.: A0010170WO01 / 1123-789WO01 secondary processing circuitry 40, which may control telemetry circuitry 56, as well as perform other functions. Some other functions may include error checking of the operation of primary processing circuitry 50.

[0090] External charging device 208 may also include one or more temperature sensors, illustrated as temperature sensor 59 within charging head 226, similar to temperature sensor 39 of FIG.2. As shown in FIG.3, temperature sensor 59 may be disposed within charging head 226. In other examples, one or more temperature sensors of temperature sensor 59 may be disposed within housing 24. For example, charging head 226 may include one or more temperature sensors positioned and configured to sense the temperature of external primary coil 48 and / or a surface of the housing of charging head 226. In some examples, external charging device 208 may not include temperature sensor 59.

[0091] In general, external charging device 208 comprises any suitable arrangement of hardware, alone or in combination with software and / or firmware, to perform the techniques ascribed to external charging device 208, and primary processing circuitry 50, user interface 54, telemetry circuitry 56, and charging circuitry 68 of external charging device 208, and / or any equivalents thereof. In various examples, external charging device 208 may include one or more processors, such as one or more microprocessors, DSPs, ASICs, FPGAs, or any other equivalent integrated or discrete logic circuitry, as well as any combinations of such components. External charging device 208 also, in various examples, may include a memory 52, such as RAM, ROM, PROM, EPROM, EEPROM, flash memory, a hard disk, a CD-ROM, comprising executable instructions for causing the one or more processors to perform the actions attributed to them. Moreover, although primary processing circuitry 50, telemetry circuitry 56, charging circuitry 68, and temperature sensor 59 are described as separate modules, in some examples, primary processing circuitry 50, telemetry circuitry 56, charging circuitry 68, and / or temperature sensor 59 are functionally integrated. In some examples, primary processing circuitry 50, telemetry circuitry 56, charging circuitry 68, and / or temperature sensor 59 correspond to individual hardware units, such as ASICs, DSPs, FPGAs, or other hardware units.

[0092] Memory 52 may store instructions that, when executed by primary processing circuitry 50, cause primary processing circuitry 50 and external charging device 208 to provide the functionality ascribed to external charging device 208 throughout this disclosure, and / or any equivalents thereof. For example, memory 52 may includeDocket No.: A0010170WO01 / 1123-789WO01 instructions that cause primary processing circuitry 50 to control the power level used to charge IMD 210 in response to the determined temperatures for the housing / external surface(s) of IMD 210, as communicated from IMD 210, or instructions for any other functionality. Memory 52 may include a record of selected power levels, sensed temperatures, determined temperatures, or any other data related to charging rechargeable power source 18, described above in relation to FIG.2. Memory 52 may store instructions that when executed by primary processing circuitry 50 may control the operation of indicator lights 64 as described above in relation to FIG.1. Primary processing circuitry 50 may determine one or more operational states, e.g., of external charging device 208 and selectively control indicator lights 64 based on the operational state.

[0093] Primary processing circuitry 50 may, when requested, transmit any stored data in memory 52 to another computing device for review or further processing, such as to server 112 depicted in FIG.1. Primary processing circuitry 50 may be configured to access memory, such as memory 32 of IMD 10 and / or memory 52 of external charging device 208, to retrieve information comprising instructions, formulas, and determined values for one or more constants.

[0094] User interface 54 may include buttons, such as control 62 or a keypad, lights, such as indicator lights 64, a speaker for voice commands, a display, such as a liquid crystal display (LCD), light-emitting diode (LED), or cathode ray tube (CRT). In some examples, the display may be a touch screen. Control 62 may be implemented as any type of component that may receive user input and provide an indication of the user input to primary processing circuitry 50. Control 62 may be a knob, switch, button and so on. As discussed in this disclosure, primary processing circuitry 50 may present and receive information relating to the charging and / or the status of rechargeable power source 18 (e.g., a battery) of IMD 210 via user interface 54. For example, user interface 54 may indicate when charging is occurring, quality of the alignment between internal primary coil 228 or external primary coil 48 and secondary coil 16 of IMD 210, the selected power level, current charge level of rechargeable power source 18, duration of the current recharge session, anticipated remaining time of the charging session, sensed temperatures, or any other information. Primary processing circuitry 50 may receive some of the information displayed on user interface 54 from IMD 210 in some examples. In some examples, user interface 54 may provide an indication to the user of the status of power source 18 of IMD 210. For example, user interface 54 may provide information indicativeDocket No.: A0010170WO01 / 1123-789WO01 of the status of power source 18 (e.g., a battery status) including an indication of at least one of an amount (e.g., a percentage) of remaining charge, a time until recharge, a recharge interval, an expected date of battery depletion, or an expected date of battery recharge.

[0095] User interface 54 may also receive user input via user interface 54. The input may be, for example, in the form of pressing a button on a keypad or selecting an icon from a touch screen. The input may change programmed settings, start or stop therapy, request starting or stopping a recharge session, a desired level of charging, or one or more statistics related to charging rechargeable power source 18 (e.g., the cumulative thermal dose). In this manner, user interface 54 may allow the user to view information related to the operation of IMD 210. For example, control 62 may provide an input to primary processing circuitry 50 to cause primary processing circuitry 50 to start or stop delivery of wireless power to the power receiving device, e.g., IMD 10 or IMD 210 described above in relation to FIGS.1 and 2.

[0096] Charging circuitry 58 may include one or more circuits that generate an electrical signal, and an electrical current, within external primary coil 48. Charging circuitry 58 may generate an alternating current of specified amplitude and frequency in some examples. In other examples, charging circuitry 58 may generate a direct current. In any case, charging circuitry 58 may be capable of generating electrical signals, and subsequent magnetic fields, to transmit various levels of power to IMD 210. In this manner, charging circuitry 58 may be configured to charge rechargeable power source 18 of IMD 210 with the selected power level.

[0097] Power source 60 may deliver operating power to the components of external charging device 208. Power source 60 may also deliver the operating power to drive external primary coil 48 during the charging process. Power source 60 may include a battery and a power generation circuit to produce the operating power. In some examples, a battery of power source 60 may be rechargeable to allow extended portable operation. In other examples, power source 60 may draw power from a wired voltage source such as a consumer or commercial power outlet.

[0098] Telemetry circuitry 56 supports wireless communication between IMD 210 and external charging device 208 under the control of primary processing circuitry 50. Telemetry circuitry 56 may also be configured to communicate with another computing device via wireless communication techniques, or direct communication through a wiredDocket No.: A0010170WO01 / 1123-789WO01 connection. In some examples, telemetry circuitry 56 may be substantially similar to telemetry circuitry 36 of IMD 210 described herein, providing wireless communication via an RF or proximal inductive medium. In some examples, telemetry circuitry 56 includes an antenna 57, which may take on a variety of forms, such as an internal or external antenna. Although telemetry circuitry 56 and telemetry circuitry 36 may each include dedicated antennas for communications between these devices, telemetry circuitry 56 and telemetry circuitry 36 may instead, or additionally, be configured to utilize inductive coupling from internal primary coil 228 and / or external primary coil 48 to transfer data.

[0099] Examples of local wireless communication techniques that may be employed to facilitate communication between external charging device 208 and IMD 210 include radio frequency and / or inductive communication according to any of a variety of standard or proprietary telemetry protocols, or according to other telemetry protocols such as the Institute of Electrical and Electronics Engineers (IEEE) 802.11x or Bluetooth specification sets. In this manner, other external devices may be capable of communicating with external charging device 208 without needing to establish a secure wireless connection.

[0100] In operation, primary processing circuitry 50, and / or secondary processing circuitry 40, may control one or more sets of indicator lights 64 to provide information to a user about communication, charging efficiency, therapy status of the IMD and so on. For example, primary processing circuitry 50 may determine whether communication circuitry, e.g., telemetry circuitry 56, has established a communication link with a power receiving device (e.g., IMD 10 or IMD 210 depicted in FIGS.1 and 2). Primary processing circuitry 50 may also determine whether the power receiving device (e.g., IMD 10 or IMD 210) is receiving wireless power, e.g., via charging circuitry 68 and internal primary coil 228, or charging circuitry 58 and external primary coil 48.

[0101] Primary processing circuitry 50 may use any one or more system metrics to determine power transfer to IMD 210. In some examples, IMD 210 may send a signal indicating an amount of current output by the recharge circuitry of IMD 210. In other examples, primary processing circuitry 50 may calculate other system metrics, such as alignment of internal primary coil 228 to secondary coil 16 of IMD 210 using any of several techniques, including heat calculations, temperature measurements, detection of metal, and so on. Primary processing circuitry 50 may compare any of the calculatedDocket No.: A0010170WO01 / 1123-789WO01 power transfer, power efficiency, alignment, IMD 210 current, etc. to a threshold stored at memory 52. When above the threshold, primary processing circuitry 50 may cause indicator lights 64 to output a signal.

[0102] In some examples, primary processing circuitry 50 of external charging device 208 may be configured to determine the operational states of IMD 210. In some examples, primary processing circuitry 50 of external charging device 208 is configured to determine whether IMD 210 is in the first device state (e.g., when IMD 210 is configured to deliver therapy) and / or the second devices state (e.g., a deep sleep state). Primary processing circuitry 50 of external charging device 208 may determine the operational state of IMD 210 instead of or in addition to processing circuitry 30 of IMD 210 as described above. Further, primary processing circuitry 50 of external charging device 208 may be configured to perform any of the functions related to determining a status of power source 18 of IMD 210, as well as additionally or alternatively determining a status of power source 60 of external charging device 208.

[0103] In some examples, primary processing circuitry 50 may control haptic output circuitry 72 to provide a tactile sensation above the patient’s perception level. For example, haptic output circuitry may vibrate or provide some similar tactile sensation. In some examples, primary processing circuitry 50 may control haptic output circuitry 72 to vibrate at a constant level for a specified duration, may output a pattern of vibration, or some similar haptic feedback for the patient. In some examples, the haptic feedback may indicate poor coupling, and the haptic feedback may fade as the coupling improves, e.g., the power receiving device is receiving wireless power above the first threshold. In this manner, the patient may receive feedback without the need to view user interface 54 of external charging device 208, or the user interface of some other device, e.g., a smart phone, tablet and so on. As discussed above, primary processing circuitry 50 may be configured to provide similar notifications or outputs related to the determination of the status of power source 18 of IMD 210. For example, primary processing circuitry 50 may control haptic output circuitry 72 to vibrate in a specific pattern to indicate to and / or alert the patient of the status of power source 18 of IMD 210.

[0104] FIG.4 is a block diagram of an example programmer of FIG.1. Programmer 204 may be a device for inputting information relating to a patient, receiving information from IMD 210, and updating IMD 210. In some examples, such as where programmer 204 is a patient programmer, programmer 204 can be a wearable communication device,Docket No.: A0010170WO01 / 1123-789WO01 with a therapy request input integrated into a key fob or a wristwatch, handheld computing device, smart phone, computer workstation, or networked computing device. Practically, programmer 204 can be a bring-your-own device provided by the patient, or provided by the healthcare provider in connection with the implantable device.

[0105] In some examples, such as where programmer 204 is physician / clinician programmer, programmer 204 is a tablet computing device that is preloaded with a specific application to interface with IMD 210. The physician or clinician may interact with programmer 204 for programming IMD 210. As described in more detail, the physician or clinician may utilize examples of a workflow to program IMD 210, as well as view information about the usage of IMD 210.

[0106] Programmer 204 generally comprises a processing circuitry 82, a memory 84, a user interface 86, communications circuitry 88, and a power source 90. Processing circuitry 82 can be any programmable device that accepts digital data as input, is configured to process the input according to instructions or algorithms, and provides results as outputs. In an example, processing circuitry 82 can be a central processing unit (CPU) configured to carry out the instructions of a computer program. Processing circuitry 82 is therefore configured to perform at least basic arithmetical, logical, and input / output operations. In one or more examples, processing circuitry 82 corresponds to individual hardware units, such as microprocessors, ASICs, DSPs, FPGAs, or other hardware units. In other examples, processing circuitry 82 can correspond to multiple individual hardware units, such as microprocessors, ASICs, DSPs, FPGAs, or other hardware units.

[0107] Memory 84 can comprise volatile or non-volatile memory as required by processing circuitry 82 to not only provide space to execute the instructions or algorithms, but to provide the space to store the instructions themselves. In one or more examples, volatile memory can include random access memory (RAM), dynamic random-access memory (DRAM), or static random access memory (SRAM), for example. In one or more examples, non-volatile memory can include read-only memory, flash memory, ferroelectric RAM, hard disk, floppy disk, magnetic tape, or optical disc storage, for example. The foregoing lists in no way limit the type of memory that can be used.

[0108] User interface 86 can include a button or keypad, lights, a speaker for voice commands, a knob able to turn, a display, such as a liquid crystal display (LCD), light- emitting diode (LED), or cathode ray tube (CRT). In some examples, the display may be aDocket No.: A0010170WO01 / 1123-789WO01 touch screen. Processing circuitry 82 can present and receive information relating to electrical stimulation and resulting therapeutic effects via user interface 86. For example, processing circuitry 82 can receive patient input via user interface 86. The input can be, for example, in the form of pressing a button on a keypad or selecting an icon from a touch screen. Processing circuitry 82 can also present information to the patient in the form of alerts related to delivery of the electrical stimulation to a patient or a caregiver via user interface 86. In some examples, user interface 86 may provide an indication to the user of the status of power source 18 of IMD 210. For example, user interface 86 may provide information indicative of the status of power source 18 (e.g., a battery status) including an indication of at least one of an amount (e.g., a percentage) of remaining charge, a time until recharge, a recharge interval, an expected date (e.g., including month, day, and year) of battery depletion, or an expected date (e.g., including month, day, and year) of battery recharge.

[0109] Communications circuity 88 is configured to interface with IMD 210 and optionally, server 112 (FIG.1). Communications circuity 88 supports wireless communication between IMD 210 and, optionally, between server 112 and programmer 204 under the control of processing circuitry 82. Communications circuity 88 can also be configured to communicate with another computing device via wireless communication techniques, or direct communication through a wired connection. Communications circuity 88 can provide wireless communication via an RF or proximal inductive medium. In some examples, communications circuity 88 can include an antenna, which may take on a variety of forms, such as an internal or external antenna.

[0110] Examples of local wireless communication techniques that may be employed to facilitate communication between programmer 204 and another computing device include RF communication according to the 802.11 or Bluetooth specification sets, infrared communication, e.g., according to the Infrared Data Association (IrDA) standard, or other standard or proprietary telemetry protocols. In this manner, other external devices may be capable of communicating with programmer 204 without needing to establish a secure wireless connection.

[0111] Power source 90 delivers operating power to the components of programmer 204. Power source 90 can include a battery and a power generation circuit to produce the operating power. In some examples, the battery may be rechargeable by for example, an exterior power source.Docket No.: A0010170WO01 / 1123-789WO01

[0112] Accordingly, as described, programmer 204 allows the user (e.g., patient, caretaker, clinician, physician) to program a therapy schedule and adjust therapy parameters (e.g., amplitude, frequency, and / or pulse width). A therapy schedule may include a frequency and duration of stimulation therapy based on certain time intervals (e.g., times of the day, amount of days between therapy sessions, particular dates and / or days of the week for therapy sessions, total duration and / or number of therapy sessions, etc.). Programmer 204 can communicate with IMD 210 to update the functionality of IMD 210.

[0113] In some examples, programmer 204 is configured to perform one or more of the functions related to determining a status of power source 18 (e.g., a battery status) of IMD 210, as described above. For example, programmer 204, via processing circuitry 82, may be configured to estimate of the status of power source 18 for one or more periods of time and / or one or more devices states of IMD 210. In some examples, programmer 204 is configured to track and / or estimate the status of power source 18 (e.g., a battery status) even when not connected to IMD 210. Programmer 204 may provide notifications related to an expected status of power source 18 of IMD 210. IMD 210 may provide updated information related to the status of power source 18 to programmer 204.

[0114] FIG.5 is a graph 500 illustrating an example current drain during various device states of IMD 10 or IMD 210 over a period of time, and is described in relation to the components of IMD 210 from FIG.2. In the example of FIG.5, line 502 represents the level of current being supplied or discharged by a battery (e.g., power source 18 of FIG.2) to electrical components of IMD 210 over time. As illustrated, the amount of current supplied by a battery (e.g., power source 18 of FIG.2) may vary depend on one or more operations states of a device (e.g., IMD 210 of FIG.2). For example, a device operational state, such as a first device state, includes where the IMD 210 may be actually delivering therapy (time period 504A in the example of FIG.5), or where the components needed for IMD 210 to deliver therapy are receiving power but not actually delivering therapy (e.g., a device “standby” state) (time period 504B in the example of FIG.5). Together, time period 504A and 504B represent where IMD 210 is in the first device state, described above in connection with FIG.2. As another example, a device state may include where IMD 210 may have one or more components disconnected or partially disconnected from power source 18 or otherwise consuming less power (e.g., a deep sleep state) (time period 506 in the example of FIG.5). Time period 506 represents where IMDDocket No.: A0010170WO01 / 1123-789WO01 210 is in the second device state, described above in connection with FIG.2. In the second device state, very few components may be operational, such as just enough to track time or schedule for the next time to exit the second device state and re-enter the first device state for delivering therapy or performing other operations during which the current drain can again be measured.

[0115] In the example of FIG.5, a device (e.g., IMD 210) is configured to draw a different (e.g., higher) current level from a power source (e.g., power source 18) during the first period of time in which IMD 210 in a first device state (e.g., time periods 504A and 504B, collectively the first period of time) as compared to the second period of time in which IMD 210 is in the second device state (e.g., time period 506). For example, during time period 504A, when IMD 210 is delivering therapy, such as one or more pulses of electrical stimulation therapy, IMD 210 may draw (and power source 18 may provide) a peak current level 512 and an average current level 514. Peak current level 512 may be a maximum current delivered during electrical stimulation (e.g., a maximum amplitude of a pulse of electrical stimulation), such as 1 to 20 milliamps or about 1 to about 20 milliamps. Average current level 514 may represent the average current level over a period of stimulation (e.g., time period 504A), such as 10 microamps to 1000 microamps or about 10 microamps to about 1000 microamps. Between periods (e.g., pulses) of electrical stimulation, IMD may draw a baseline current level 516. Additionally, where the components needed for IMD 210 to deliver therapy are receiving power but not actually delivering therapy (e.g., a device “standby” state and / or where IMD 210 performs certain administrative operations) (time period 504B in the example of FIG.5), IMD 210 may draw baseline current level 516. During time period 506, when IMD 210 is in the second device state (e.g., a deep sleep state), IMD may draw a reduced current level 518. In some examples, reduced current level 518 is less than baseline current level 516, such that IMD 210 uses less power during the second devices state (e.g., a deep sleep state) as compared to the first device state. In some examples, reduced current level 518 is about 140 nanoamps. The periods of reduced current draw during different periods shown in FIG.5 may enable IMD 210 to conserve power from power source 18 during different periods of time. In some examples, IMD 210 may have temporary periods of time during which the current draw in time period 504 may be less than the current draw during some or all of time period 506.Docket No.: A0010170WO01 / 1123-789WO01

[0116] The example of FIG.5 shows periods of stimulation, standby, deep sleep state and / or reduced power to illustrate current draw over different periods of time. In some examples, IMD 210 automatically cycles between periods of therapy delivery (e.g., one or more time periods such as time period 504A) and periods where components needed for IMD 210 to deliver therapy are receiving power but not actually delivering therapy (e.g., a device “standby” state) (time period 504B in the example of FIG.5). In some examples, IMD 210 automatically transitions to periods of deep sleep state or reduced power state (e.g., time period 506) based on one or more therapy schedules or one of more device schedules. However, IMD 210 may also be configured to transition between different periods (e.g., time period 504A, time period 504B, and time period 506) in response to user input.

[0117] FIG.6A is a conceptual diagram illustrating an example user interface 600 related to a rechargeable battery according to this disclosure. User interface 600 may include a screen 602 with various boxes or areas that displays relevant information related to a device, such as IMD 10 or IMD 210. User interface 600 may be an example of user interface 54 of external charging device 208 as shown in FIG.3, user interface 86 of programmer 204 as shown in FIG.4 (which may be a patient programmer or a clinician programmer), or another suitable device. User interface 600 may provide a user with information about a battery of a device, and will be discussed in connection with power source 18 of IMD 210 from FIG.2. Although user interface 600 may have static boxes to display information related to power source 18, one or more pop-up boxes, tabs, or other types of alerts are contemplated.

[0118] In the example of FIG.6A, user interface 600 provides a user (which may be a patient, a clinician, or another suitable user), with information related to the status of a power source. For example, screen 602 includes box 640A showing information related to a status of power source 18 of IMD 210. Box 640A may include an indication of the status of power source 18 of IMD 210, including various charts, graphs, colors, numerical, or pictorial indications of the status of power source 18 of IMD 210. For example, box 640A includes a charge indication 642 (represented as a numerical percentage of charge remaining). In some examples, box 640A includes a date and / or interval of an expected next recharge (e.g., when power source 18 of IMD 210 needs to be recharged). Additionally, box 640A may include one or more options (e.g., buttons, toggles, or another suitable mechanism) for a user to access information related to powerDocket No.: A0010170WO01 / 1123-789WO01 source 18. For example, box 640A includes a button 644 to prompt a calculation of the estimated recharge interval (which may be a time until recharge, or an expected date of battery recharge, as discussed in connection with FIG.2). In some examples, including examples using a non-rechargeable power source, button 644 may prompt a calculation of an expected date (e.g., including month, day, and year) of battery depletion. In this way, while IMD 210 may automatically update estimates of the status of power source 18 and / or estimate recharge date at one or more intervals, user interface 600 enables a user to “refresh” or “update” such determinations. As discussed above, such determinations may be based on and / or include the aggregate of at least the measured current drain from power source 18 during the first device state (e.g., when IMD 210 is configured to deliver therapy) and the estimated current drain during the second device state (e.g., a deep sleep state). In some examples screen 602 includes box 630, which may provide an indication of when the user and / or the device last “refreshed” or “updated” the determination of power source 18 (e.g., a battery status). In some examples, one or more notifications may be generated on screen 602 related to power source 18, such as periodic notifications or prompts for a user to recharge power source 18. For example, in response to power source 18 dropping below a predefined threshold, screen 602 may include one or more prompts or reminders to recharge power source 18.

[0119] FIG.6B is a conceptual diagram illustrating an example part of a user interface, such as user interface 600 of FIG.6A. In the example of FIG.6B, a box 640B includes a charge indication 648, which is represented as a graph of battery charge versus time. Charge indication 648 may include information related to an actual charge consumption (e.g., measurements or estimates) over time, as well as, in some examples, a prediction of a future charge consumption. For example, a future charge consumption may take into account a therapy schedule to predict an estimated current drain and / or date of expected recharge. The system may update this estimate based on actual measurements as IMD 210 functions. Although the examples of FIG.6A and 6B illustrate various ways to display information related to the state of a power source (e.g., power source 18 of IMD 210), other ways of displaying information may be used instead of, or in addition to, the examples shown. Box 640B includes a button 644 to prompt a calculation of the estimated recharge interval (which may be a time until recharge, or an expected date of battery recharge, as discussed in connection with FIG.2).Docket No.: A0010170WO01 / 1123-789WO01

[0120] FIG.6C is a conceptual diagram illustrating an example part of a user interface, such as user interface 600 of FIG.6A. In the example of FIG.6C, a box 640C includes an indication of a date of charge depletion 650. The date of charge depletion 650 may be a day, date, or other indicator of when power source 18 of IMD 210 is depleted and / or depleted below a predetermined level, which could be a level that provides some reserve operational battery capacity or the level needed for proper functioning of IMD 210. This predetermined level may correspond to a voltage level of the battery. In some examples, the date of charge depletion 650 may be the same as the date and / or interval of an expected next recharge (e.g., when power source 18 of IMD 210 needs to be recharged). For example, where a user only desires to recharge at long intervals and / or only when power source 18 is depleted or nearly depleted, the date of charge depletion 650 may be the same as the date and / or interval of an expected next recharge. However, in some examples, the date of charge depletion 650 may be different from the date and / or interval of an expected next recharge (e.g., when power source 18 of IMD 210 needs to be recharged). For example, a user may desire to set a recharge interval and / or date of recharge before the charge depletion date. In some examples, the recharge interval may include a period of time before of the charge depletion date. As an illustrative example, processing circuitry 30 of IMD 210 may be configured to set a monthly recharge interval, while the charge depletion date is several months away.

[0121] FIG.6D is a conceptual diagram illustrating an example user interface 660 related to a rechargeable battery according to this disclosure. User interface 660 may include a screen 662 with various boxes or areas that displays relevant information related to a device, such as IMD 10 or IMD 210. User interface 660 may be an example of user interface 54 of external charging device 208 as shown in FIG.3, user interface 86 of programmer 204 as shown in FIG.4 (which may be a patient programmer or a clinician programmer), or another suitable device. User interface 660 may provide a user with information about a battery of a device, and will be discussed in connection with power source 18 of IMD 210 from FIG.2. Although user interface 660 may have static boxes to display information related to power source 18, one or more pop-up boxes, tabs, or other types of alerts are contemplated.

[0122] In the example of FIG.6D, user interface 660 provides a user (which may be a patient, a clinician, or another suitable user), with information related to the status of a power source. For example, screen 662 includes box 680 showing information related to aDocket No.: A0010170WO01 / 1123-789WO01 status of power source 18 of IMD 210. Box 680 may include an indication of the status of power source 18 of IMD 210, including various charts, graphs, colors, numerical, or pictorial indications of the status of power source 18 of IMD 210. For example, box 680 includes a charge indication 682 (represented as a numerical percentage of charge remaining). In some examples, box 680 includes a date and / or interval of an expected next recharge (e.g., when power source 18 of IMD 210 needs to be recharged). Additionally, box 680 may include one or more options (e.g., buttons, toggles, or another suitable mechanism) for a user to access information related to power source 18. For example, box 680 includes a button 684 to prompt a calculation of the estimated recharge interval (which may be a time until recharge, or an expected date of battery recharge, as discussed in connection with FIG.2). In some examples, including examples using a non- rechargeable power source, button 684 may prompt a calculation of an expected date of battery depletion. In this way, while IMD 210 may automatically update estimates of the status of power source 18 and / or estimate recharge date at one or more intervals, user interface 660 enables a user to “refresh” or “update” such determinations. As discussed above, such determinations may be based on and / or include the aggregate of at least the measured current drain from power source 18 during the first device state (e.g., when IMD 210 is configured to deliver therapy) and the estimated current drain during the second device state (e.g., a deep sleep state). In some examples screen 662 includes box 670, which may provide an indication of when the user and / or the device last “refreshed” or “updated” the determination of power source 18 (e.g., a battery status). In some examples, one or more notifications may be generated on screen 662 related to power source 18, such as periodic notifications or prompts for a user to recharge power source 18. For example, in response to power source 18 dropping below a predefined threshold, screen 662 may include one or more prompts or reminders to recharge power source 18.

[0123] FIG.7 is a flow chart illustrating an example technique for estimating a battery status of a battery. The example technique of FIG.7 is discussed in relation to the components of IMD 210 as discussed in connection with FIG.2, but may be used with any of the devices of this disclosure (e.g., IMD 10 of FIG.1).

[0124] Processing circuitry 30 may determine a measured current drain from the battery (e.g., power source 18) of IMD 210 during a first period of time in which the IMD is in a first device state (702). In some examples, during the first device state and / or during the first period of time, the IMD is configured to deliver electrical stimulationDocket No.: A0010170WO01 / 1123-789WO01 therapy, monitor patient physiological parameters, or both. During the first device state and / or during the first period of time, coulomb counter 35 measures current drain from the battery (e.g., power source 18) of IMD 210 in the first device state, and / or provide the measured current drain to processing circuitry 30. Processing circuitry 30 may receive, from timer 41, information indicative of IMD events, including a time spent in the first device state, a time spent in the second device state, or one or more timestamps of at least one of IMD 210 entering or exiting the second device state. Processing circuitry 30 may determine (e.g., calculate) the duration of time spent in the first device state or the second device state.

[0125] Processing circuitry 30 may determine an estimated current drain from the battery (e.g., power source 18) of IMD 210 during a second period of time in which IMD 210 is in a second device state (704) during which the current drain or other battery usage cannot be directly measured (e.g., coulomb counter 35 is disconnected). In some examples, processing circuitry 30 accesses information indicative of a characterized current drain from the battery (e.g., power source 18) for the determination of the estimated current drain from the battery (e.g., power source 18) of IMD 210. For example, processing circuitry 30 may access one or more stored values (e.g., stored in memory 32, or available via a lookup table) indicative of the characterized current drain of IMD 210 during a the second devices state (e.g., a deep sleep state). In some examples, information indicative of characterized current drain from the battery (e.g., power source 18) is determined prior to implantation of IMD 210 into the patient.

[0126] In some examples, processing circuitry 30 receives information indicative of IMD 210 events during the second period of time for the determination of the estimated current drain from the battery (e.g., power source 18) of IMD 210. For example, processing circuitry 30 receives information (e.g., a duration of time IMD 210 was in the second device state or one or more timestamps of IMD 210 entering or exiting the second device state) from timer 41. In some examples, timer 41 includes a real-time clock. In some examples, timer 41 includes an oscillator. In some examples, timer 41 includes an oscillator and a counter for counting oscillations from the oscillator. However, in some examples, processing circuitry 30 may additionally or alternatively include the counter. Timer 41 may remain powered during the second device state. In some examples, processing circuitry 30 calculates, based on the information indicative of the characterized current drain from the battery and on the information indicative of IMD 210Docket No.: A0010170WO01 / 1123-789WO01 events, the estimated current drain for the second period of time. For example, where the characterized current drain includes an amount of current drain per unit of time (e.g., amperes per hour), processing circuitry 30 determines current drain during the second devices state (e.g., a deep sleep state) based on the amount of time spent in the second device state.

[0127] Processing circuitry 30 may determine, based on the measured current drain and the estimated current drain, a battery status of the battery (e.g., power source 18) of IMD 210 (706). For example, processing circuitry 30 determines a current drain from power source 18 over a period time based on the aggregate of at least the measured current drain from power source 18 during the first device state (e.g., when IMD 210 is configured to deliver therapy) and an estimated current drain during the second device state (e.g., a deep sleep state).

[0128] Processing circuitry 30 may generate for output information indicative of the battery status of the battery (e.g., power source 18) of IMD 210 (708). The battery status may include at least one of a percentage of remaining charge, a time until recharge, a recharge interval, an expected date of battery depletion, or an expected date of battery recharge. In some examples, information indicative of the battery status of IMD 210 includes a notification regarding the battery status. In some examples, processing circuitry 30 generates one or more of a visual, audio, tactile, haptic feedback, or related notification regarding the status of power source 18.

[0129] In some examples, processing circuitry 30 updates the battery status in response to IMD 210 exiting the second device state. For example, processing circuitry 30 may automatically update (e.g., without a user prompt) the determination of the status of power source 18 (e.g., battery status) in response to IMD 210 exiting the second device state (e.g., a deep sleep state).

[0130] This disclosure includes the following non-limiting examples.

[0131] Example 1: A system comprising: processing circuitry configured to: determine a measured current drain from a battery of an implantable medical device (IMD) during a first period of time in which the IMD is in a first device state, determine an estimated current drain from the battery of the IMD during a second period of time in which the IMD is in a second device state, determine, based on the measured current drain and the estimated current drain, a battery status of the battery of the IMD, and generate, for output, information indicative of the battery status of the battery of the IMD.Docket No.: A0010170WO01 / 1123-789WO01

[0132] Example 2: The system of example 1, wherein to determine the estimated current drain, the processing circuitry is configured to: access information indicative of a characterized current drain from the battery, receive information indicative of IMD events that occurred during the second period of time, and calculate, based on the information indicative of the characterized current drain from the battery and on the information indicative of IMD events, the estimated current drain for the second period of time.

[0133] Example 3: The system of example 2, wherein information indicative of the characterized current drain from the battery is determined prior to implantation of the IMD into a patient.

[0134] Example 4: The system of any of examples 2 to 3, wherein information indicative of IMD events comprises one or more timestamps of at least one of the IMD entering or exiting the second device state.

[0135] Example 5: The system of any of examples 2 to 4, wherein information indicative of IMD events comprises a duration of the second period of time the IMD was in the second device state.

[0136] Example 6: The system of claim 5, wherein during the second device state, a timer records the duration of the second period of time the IMD was in the second devices state.

[0137] Example 7: The system of claim 6, wherein the timer comprises at least one of a real-time clock or an oscillator.

[0138] Example 8: The system of any of examples 1 to 7, wherein during the first device state, the IMD is configured to deliver electrical stimulation therapy.

[0139] Example 9: The system of any of examples 1 to 8, wherein information indicative of the battery status of the IMD comprises at least one of a percentage of remaining charge, a time until recharge, an expected date of battery depletion, or an expected date of battery recharge.

[0140] Example 10: The system of any of examples 1 to 9, wherein information indicative of the battery status of the IMD comprises a notification regarding the battery status.

[0141] Example 11: The system of any of examples 1 to 10, further comprising a coulomb counter, wherein the coulomb counter of the IMD measures current drain from the battery of the IMD in the first device state.Docket No.: A0010170WO01 / 1123-789WO01

[0142] Example 12: The system of any example 11, wherein the system further comprises therapy generation circuitry, and wherein during the second device state, at least the coulomb counter and the therapy generation circuitry are disconnected from the battery.

[0143] Example 13: The system of example 12, wherein during the second device state, the processing circuitry is configured to control the IMD to open a switch such that at least the coulomb counter and the therapy generation circuitry are disconnected from the battery.

[0144] Example 14: The system of any of examples 1 to 13, wherein the processing circuitry is further configured to update the battery status in response to the IMD exiting the second device state.

[0145] Example 15: The system of any of examples 1 to 14, wherein to determine the estimated current drain, the processing circuitry is configured to measure a voltage of the battery.

[0146] Example 16: The system of any of examples 2 to 15, wherein to determine the estimated current drain, the processing circuitry is configured to access a lookup table, wherein the lookup table correlates at least the information indicative of IMD events and the information indicative of the characterized current drain from the battery.

[0147] Example 17: The system of any of examples 1 to 16, wherein to generate, for output, information indicative of the battery status of the battery of the IMD, the processing circuitry is configured to provide at least one of a stimulation-based notification or a haptic feedback notification to the patient.

[0148] Example 18: The system of any of examples 1 to 17, wherein the processing circuitry is further configured to periodically update the battery status of the battery of the IMD.

[0149] Example 19: A method comprising: determining, by processing circuitry, a measured current drain from a battery of an implantable medical device (IMD) during a first period of time in which the IMD is in a first device state; determining, by the processing circuitry, an estimated current drain from the battery of the IMD during a second period of time in which the IMD is in a second device state; determining, by the processing circuitry, based on the measured current drain and the estimated current drain, a battery status of the battery of the IMD; and generating for output, by the processing circuitry, information indicative of the battery status of the battery of the IMD.Docket No.: A0010170WO01 / 1123-789WO01

[0150] Example 20: The method of example 19, wherein determining the estimated current drain comprises: accessing, by the processing circuitry, information indicative of a characterized current drain from the battery; receiving, by the processing circuitry, receive information indicative of IMD events that occurred during the second period of time; and calculating, by the processing circuitry, based on the information indicative of the characterized current drain from the battery and on the information indicative of IMD events, the estimated current drain for the second period of time.

[0151] Example 21: The method of example 20, wherein information indicative of the characterized current drain from the battery is determined prior to implantation of the IMD into a patient.

[0152] Example 22: The method of any of examples 20 to 21, wherein information indicative of IMD events comprises one or more timestamps of at least one of the IMD entering or exiting the second device state.

[0153] Example 23: The method of any of example 20 to 22, wherein information indicative of IMD events comprises a duration of the second period of time the IMD was in the second device state.

[0154] Example 24: The method of examples 23, wherein during the second device state, a timer records the duration of the second period of time the IMD was in the second devices state.

[0155] Example 25: The method of example 24, wherein the timer comprises at least one of a real-time clock or an oscillator.

[0156] Example 26: The method of any of examples 19 to 25, wherein during the first device state, the IMD is configured to deliver electrical stimulation therapy.

[0157] Example 27: The method of any of examples 19 to 26, wherein information indicative of the battery status of the IMD comprises at least one of a percentage of remaining charge, a time until recharge, an expected date of battery depletion, or an expected date of battery recharge.

[0158] Example 28: The method of any of examples 19 to 27, wherein information indicative of the battery status of the IMD comprises a notification regarding the battery status.

[0159] Example 29: The method of any of examples 19 to 28, wherein a coulomb counter of the IMD measures current drain from the battery of the IMD in the first device state.Docket No.: A0010170WO01 / 1123-789WO01

[0160] Example 30: The method of any of examples 19 to 29, wherein during the second device state, at least the coulomb counter and the therapy generation circuitry are disconnected from the battery.

[0161] Example 31: The method of any of examples 19 to 30, further comprising controlling, during the second device state, the IMD to open a switch is opened such that at least the coulomb counter and the therapy generation circuitry are disconnected from the battery.

[0162] Example 32: The method of any of examples 19 to 31, further comprising: updating, by the processing circuitry, the battery status in response to the IMD exiting the second devices state.

[0163] Example 33: A system comprising: therapy generation circuitry configured to delivery electrical stimulation therapy via one or more electrodes; an processing circuitry configured to: receive, from a coulomb counter, a measured current drain from a battery of an implantable medical device (IMD) during a first period of time in which the IMD is in a first device state, access information indicative of a characterized current drain from the battery, receive information indicative of IMD events that occurred during a second period of time in which the IMD is in a second device state, and calculate, based on the information indicative of the characterized current drain from the battery and on the information indicative of IMD events, an estimated current drain for the second period of time, determine, based on the measured current drain and the estimated current drain, a battery status of the battery of the IMD, and generate, for output, information indicative of the battery status of the battery of the IMD, wherein information indicative of IMD events comprises a duration of the second period of time the IMD was in the second device state as recorded by a timer, and wherein during the second device state, at least the coulomb counter and the therapy generation circuitry are disconnected from the battery.

[0164] Example 34: The system of example 33, wherein during the second device state, the processing circuitry is configured to control the IMD to open a switch such that at least the coulomb counter and the therapy generation circuitry are disconnected from the battery.

[0165] Example 35: A computer-readable medium comprising instructions that, when executed, control processing circuitry to: determine a measured current drain from a battery of an implantable medical device (IMD) during a first period of time in which theDocket No.: A0010170WO01 / 1123-789WO01 IMD is in a first device state, determine an estimated current drain from the battery of the IMD during a second period of time in which the IMD is in a second device state, determine, based on the measured current drain and the estimated current drain, a battery status of the battery of the IMD, and generate, for output, information indicative of the battery status of the battery of the IMD.

[0166] Example 36: The system of any of examples 1 to 18, wherein the measured current drain is a first measured current drain associated with therapy delivery according to a first program, and wherein the processing circuitry is further configured to: determine a second measured current drain from the battery of the IMD during a third time period in which the IMD is in a third device state, wherein the second measured current drain is associated with therapy delivery according to a second therapy program different from the first therapy program.

[0167] Example 37: The method of any of examples 19 to 31, wherein the measured current drain is a first measured current drain associated with therapy delivery according to a first program, and wherein the method further includes: determining, by the processing circuitry, a second measured current drain from the battery of the IMD during a third time period in which the IMD is in a third device state, wherein the second measured current drain is associated with therapy delivery according to a second therapy program different from the first therapy program.

[0168] The techniques described in this disclosure may be implemented, at least in part, in hardware, software, firmware or any combination thereof. For example, various aspects of the described techniques may be implemented within one or more processors, such as fixed function processing circuitry and / or programmable processing circuitry, including one or more microprocessors, digital signal processors (DSPs), application specific integrated circuits (ASICs), field programmable gate arrays (FPGAs), or any other equivalent integrated or discrete logic circuitry, as well as any combinations of such components. The term “processor” or “processing circuitry” may generally refer to any of the foregoing logic circuitry, alone or in combination with other logic circuitry, or any other equivalent circuitry. A control unit comprising hardware may also perform one or more of the techniques of this disclosure.

[0169] Such hardware, software, and firmware may be implemented within the same device or within separate devices to support the various operations and functions described in this disclosure. In addition, any of the described units, modules orDocket No.: A0010170WO01 / 1123-789WO01 components may be implemented together or separately as discrete but interoperable logic devices. Depiction of different features as modules or units is intended to highlight different functional aspects and does not necessarily imply that such modules or units must be realized by separate hardware or software components. Rather, functionality associated with one or more modules or units may be performed by separate hardware or software components, or integrated within common or separate hardware or software components.

Claims

Docket No.: A0010170WO01 / 1123-789WO01 WHAT IS CLAIMED IS:

1. A system comprising: processing circuitry configured to: determine a measured current drain from a battery of an implantable medical device (IMD) during a first period of time in which the IMD is in a first device state, determine an estimated current drain from the battery of the IMD during a second period of time in which the IMD is in a second device state, determine, based on the measured current drain and the estimated current drain, a battery status of the battery of the IMD, and generate, for output, information indicative of the battery status of the battery of the IMD.

2. The system of claim 1, wherein to determine the estimated current drain, the processing circuitry is configured to: access information indicative of a characterized current drain from the battery, receive information indicative of IMD events that occurred during the second period of time, and calculate, based on the information indicative of the characterized current drain from the battery and on the information indicative of IMD events, the estimated current drain for the second period of time.

3. The system of claim 2, wherein information indicative of the characterized current drain from the battery is determined prior to implantation of the IMD into a patient.

4. The system of any of claims 2 or 3, wherein information indicative of IMD events comprises one or more timestamps of at least one of the IMD entering or exiting the second device state.Docket No.: A0010170WO01 / 1123-789WO01 5. The system of any of claims 2 through 4, wherein the information indicative of IMD events comprises a duration of the second period of time the IMD was in the second device state.

6. The system of claim 5, wherein during the second device state, a timer records the duration of the second period of time the IMD was in the second devices state.

7. The system of claim 6, wherein the timer comprises at least one of a real-time clock or an oscillator.

8. The system of any of claims 1 through 7, wherein during the first device state, the IMD is configured to deliver electrical stimulation therapy.

9. The system of any of claims 1 through 8, wherein information indicative of the battery status of the IMD comprises at least one of a percentage of remaining charge, a time until recharge, an expected date of battery depletion, or an expected date of battery recharge.

10. The system of any of claims 1 through 6, further comprising a coulomb counter, wherein the coulomb counter of the IMD measures current drain from the battery of the IMD in the first device state.

11. The system of claim 10, further comprising therapy generation circuitry, wherein during the second device state, at least the coulomb counter and the therapy generation circuitry are disconnected from the battery.

12. The system of claim 11, wherein during the second device state, the processing circuitry is configured to control the IMD to open a switch such that at least the coulomb counter and the therapy generation circuitry are disconnected from the battery.

13. The system of any of claims 1 through 12, wherein the processing circuitry is further configured to update the battery status in response to the IMD exiting the second device state.Docket No.: A0010170WO01 / 1123-789WO01 14. The system of any of claims 2 through 13, wherein to determine the estimated current drain, the processing circuitry is configured to access a lookup table, wherein the lookup table correlates at least the information indicative of IMD events and the information indicative of the characterized current drain from the battery.

15. The system of any of claims 1 through 14, wherein to generate, for output, information indicative of the battery status of the battery of the IMD, the processing circuitry is configured to provide at least one of a stimulation-based notification or a haptic feedback notification to the patient.

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