Alternating polarity stimulation

Abstract

The present invention relates to alternating polarity focused multi-pole stimulation (FMP) techniques for use with medical devices, such as implantable medical devices. Presented herein is a method comprising: converting an input signal into a plurality of alternating polarity focused multipole stimulation signals; and sequentially delivering the plurality of alternating polarity focused multipolar stimulation signals to a recipient via a first stimulation channel.

Description

Technical Field

[0001] The present invention generally relates to electrical stimulation in implantable medical devices. Background Art

[0002] In recent decades, medical devices have provided a wide range of therapeutic benefits to recipients. Medical devices can include internal or implantable components / devices, external or wearable components / devices, or combinations thereof (e.g., devices having external components that communicate with implantable components). Medical devices, such as traditional hearing aids, partially or fully implantable hearing prostheses (e.g., bone conduction devices, mechanical stimulators, cochlear implants, etc.), pacemakers, defibrillators, functional electrical stimulation devices, and other medical devices, have been successful for many years in performing life-saving and / or lifestyle-improving functions and / or recipient monitoring.

[0003] Over the years, the types of medical devices and the range of functions performed by them have increased. For example, many medical devices sometimes referred to as "implantable medical devices" now typically include one or more instruments, devices, sensors, processors, controllers, or other functional mechanical or electrical components that are permanently or temporarily implanted within a recipient. These functional devices are typically used to diagnose, prevent, monitor, treat, or manage diseases / injuries or their symptoms, or to study, replace, or modify anatomical structures or physiological processes. Many of these functional devices utilize power and / or data received from an external device that is part of or operates in conjunction with the implantable component. Summary of the Invention

[0004] In one aspect, a method is provided. The method includes: converting an input signal into a plurality of alternating polarity focused multipolar stimulation signals; and sequentially delivering the plurality of alternating polarity focused multipolar stimulation signals via a first stimulation channel to a recipient.

[0005] In another aspect, a method is provided. The method includes: receiving an input signal at an implantable medical device system; converting the input signal into a plurality of multipolar stimulation signals; and delivering each of the plurality of multipolar stimulation signals to a recipient of the implantable medical device system using only unipolar stimulation pulses.

[0006] In another aspect, an implantable medical device system is provided. The implantable medical device system includes: one or more input elements configured to receive environmental signals; one or more processors configured to convert a first portion of the environmental signals into control signals representing at least a first multipolar stimulation signal and convert a second portion of the environmental signals into control signals representing at least a second multipolar stimulation signal; and a stimulator unit configured to generate the at least first multipolar stimulation signal and the at least second multipolar stimulation signal from the control signals and sequentially deliver the at least first multipolar stimulation signal and the at least second multipolar stimulation signal to a recipient of the implantable medical device via a selected stimulation channel, wherein the at least first multipolar stimulation signal and the at least second multipolar stimulation signal have opposite polarity attributes.

[0007] In another aspect, one or more non-transitory computer-readable storage media including instructions are provided. The instructions, when executed by a processor, cause the processor to: convert at least a portion of a first sound signal into a first multipolar stimulation signal; cause a stimulator unit to deliver the first multipolar stimulation signal to a recipient via a selected stimulation channel, wherein the first multipolar stimulation signal has a first set of polarity attributes; convert a portion of at least a second sound signal into a second multipolar stimulation signal; and cause the stimulator unit to deliver the second multipolar stimulation signal to the recipient via the selected stimulation channel, wherein the second multipolar stimulation signal has a second set of polarity attributes opposite to the first set of polarity attributes. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Embodiments of the present invention are described herein in connection with the accompanying drawings, in which:

[0009] Figure 1A is a schematic diagram showing a cochlear implant system according to certain embodiments presented herein;

[0010] Figure 1B is a side view of a recipient of a sound processing unit of a cochlear implant system being worn Figure 1A ;

[0011] Figure 1C is Figure 1A a schematic diagram of components of a cochlear implant system;

[0012] Figure 1D is Figure 1A a block diagram of a cochlear implant system;

[0013] Figure 2 is a schematic diagram showing an exemplary biphasic stimulation signal;

[0014] Figure 3is a schematic diagram showing an exemplary single-phase stimulation signal;

[0015] Figure 4 is a schematic diagram showing an exemplary alternating-polarity focused multipolar stimulation signal according to certain embodiments presented herein;

[0016] Figure 5 is another schematic diagram showing an exemplary alternating-polarity focused multipolar stimulation signal according to certain embodiments presented herein;

[0017] Figure 6 is a schematic diagram showing a vestibular nerve stimulator according to certain embodiments presented herein;

[0018] Figure 7 is a schematic diagram showing a retinal prosthesis according to certain embodiments presented herein;

[0019] Figure 8 is a flowchart of a method according to certain embodiments presented herein; and

[0020] Figure 9 is a flowchart of another method according to certain embodiments presented herein. DETAILED DESCRIPTION

[0021] Presented herein are alternating-polarity focused multipolar (FMP) stimulation techniques for use with medical devices (e.g., implantable medical devices). For ease of description only, the alternating-polarity focused multipolar stimulation techniques presented herein are described primarily with reference to a particular implantable medical device system, namely a cochlear implant system. However, it should be understood that the techniques presented herein can also be implemented by other types of implantable medical devices, non-implantable medical devices, and / or other stimulation devices. For example, the alternating-polarity focused multipolar stimulation techniques can be implemented by other auditory prostheses or systems including other auditory prostheses (e.g., middle ear auditory prostheses, bone conduction devices, direct acoustic stimulators, electroacoustic prostheses, auditory brain stimulators, etc.). The techniques presented herein can also be used with tinnitus treatment devices, vestibular devices (e.g., vestibular implants), visual devices (i.e., bionic eyes), sensors, pacemakers, drug delivery systems, defibrillators, functional electrical stimulation devices, catheters, seizure devices (e.g., devices for monitoring and / or treating seizure events), sleep apnea devices, electroporation devices, and the like.

[0022] Figures 1A-1D is a diagram showing an exemplary cochlear implant system 102 configured to implement certain embodiments of the techniques presented herein. The cochlear implant system 102 includes an external component 104 / implantable component 112. In Figures 1A-1D the example, the implantable component is sometimes referred to as a "cochlear implant". Figure 1Ais a schematic diagram showing an implantable component 112 in the head 141 of an implant recipient, while Figure 1B is a schematic diagram of an external component 104 worn on the head 141 of the recipient. Figure 1C is another schematic diagram of the cochlear implant system 102, while Figure 1D is a block diagram showing additional details of the cochlear implant system 102. For ease of description, Figures 1A-1D will generally be described together.

[0023] As noted, the cochlear implant system 102 includes an external component 104 configured to be directly or indirectly attached to the recipient's body, and an implantable component 112 configured to be implanted in the recipient. In Figures 1A-1D example, the external component 104 includes a sound processing unit 106, and the implantable component 112 includes an internal coil 114, a stimulator unit 142, and an elongated stimulation assembly 116 configured to be implanted in the recipient's cochlea.

[0024] In Figures 1A-1D example, the sound processing unit 106 is an off-the-ear (OTE) sound processing unit, sometimes referred to herein as an OTE component, which is configured to send data and power to the implantable component 112. Generally, the OTE sound processing unit is a component having a generally cylindrical housing 105 and configured to be magnetically coupled to the recipient's head (e.g., including an integrated magnet configured to be magnetically coupled to a magnet in the implantable component 112). The OTE sound processing unit 106 also includes an integrated external coil 108 configured to be inductively coupled to the implantable coil 114.

[0025] It should be understood that the OTE sound processing unit 106 is merely illustrative of an external device that can operate with the implantable component 112. For example, in an alternative example, the external component may include a behind-the-ear (BTE) sound processing unit or a micro-BTE sound processing unit and a separate external component. Generally, the BTE sound processing unit includes a housing shaped to be worn on the recipient's outer ear and connected to a separate external coil via a cable assembly (cable), where the external coil is configured to be inductively coupled to the implantable coil 114. It should also be understood that alternative external components may be located in the recipient's ear canal, worn on the body, etc.

[0026] Figures 1A-1DFIG. shows that the cochlear implant system 102 includes an arrangement of external components. However, it should be appreciated that embodiments of the present invention may be implemented in a cochlear implant system having an alternative arrangement. For example, the embodiments presented herein may be implemented by a fully implantable cochlear implant or other fully implantable medical device. A fully implantable medical device is a device in which all components are configured to be implanted under the skin / tissue of a recipient. Since all components are implantable, a fully implantable medical device operates without an external device for at least a limited period of time. The external device may be used, for example, to charge an internal power source (battery).

[0027] Returning to Figures 1A-1D a specific example of Figure 1D FIG. shows that the OTE sound processing unit 106 includes one or more input devices 113 configured to receive input signals (such as sound signals or data signals). The one or more input devices 113 include one or more sound input devices 118 (such as microphones, audio input ports, pickup coils, etc.), one or more auxiliary input devices 119 (such as audio ports, such as direct audio input (DAI), data ports, such as universal serial bus (USB) ports, cable ports, etc.), and a wireless transmitter / receiver (transceiver) 120. However, it should be understood that the one or more input devices 113 may include additional types of input devices and / or fewer input devices (for example, the wireless transceiver 120 and / or one or more auxiliary input devices 119 may be omitted).

[0028] The OTE sound processing unit 106 also includes an external coil 108, a charging coil 121, a closely coupled transmitter / receiver (transceiver) 122 (sometimes referred to as a radio frequency (RF) transceiver 122), at least one rechargeable battery 123, and a processing module 124. The processing module 124 includes one or more processors 125 and a memory device (memory) 126 including alternating polarity processing logic 128. The memory device 126 may include any one or more of the following: non-volatile memory (NVM), ferroelectric random access memory (FRAM), read-only memory (ROM), random access memory (RAM), disk storage media devices, optical storage media devices, flash memory devices, electrical, optical, or other physical / tangible memory storage devices. The one or more processors 125 are, for example, a microprocessor or a microcontroller that executes the instructions of the alternating polarity processing logic 128 stored in the memory device 126 (for example, executes instructions for implementing the alternating polarity focused multipolar stimulation technique presented herein).

[0029] The implantable component 112 includes an implant body (main module) 134, a lead region 136, and an intracochlear stimulation assembly 116, all of which are configured to be implanted beneath the skin / tissue (tissue) 115 of a recipient. The implant body 134 generally includes an airtight sealed housing 138 in which an RF interface circuitry 140 and a stimulator unit 142 are disposed. The implant body 134 also includes an internal / implantable coil 114, which is generally outside the housing 138 but is connected to the transceiver 140 via an airtight feedthrough ( Figure 1D not shown).

[0030] As described, the stimulation assembly 116 is configured to be at least partially implanted in the cochlea of the recipient. The stimulation assembly 116 includes a plurality of longitudinally spaced intracochlear electrical stimulation contacts / electrodes 144 that together form a contact or electrode array 146 for delivering electrical stimulation (current) to the cochlea of the recipient.

[0031] The stimulation assembly 116 extends through an opening (such as a cochleostomy, round window, etc.) in the cochlea of the recipient and has a proximal end connected to the stimulator unit 142 via the lead region 136 and an airtight feedthrough ( Figure 1D not shown). The lead region 136 includes a plurality of conductors (wires) that electrically couple the electrodes 144 to the stimulator unit 142. The implantable component 112 also includes electrodes external to the cochlea, sometimes referred to as extracochlear electrodes (ECE) 139.

[0032] As described, the cochlear implant system 102 includes an external coil 108 and an implantable coil 114. Generally, a magnet is fixed relative to each of the external coil 108 and the implantable coil 114. The magnet fixed relative to the external coil 108 and the implantable coil 114 facilitates the operational alignment of the external coil 108 with the implantable coil 114. This operational alignment of the coils enables the external component 104 to transmit data as well as power to the implantable component 112 via a tightly coupled wireless link formed between the external coil 108 and the implantable coil 114. In some examples, the tightly coupled wireless link is a radio frequency (RF) link. However, various other types of energy transfer (such as infrared (IR), electromagnetic, capacitive, and inductive transfer) can be used to transfer power and / or data from the external component to the implantable component, and thus, Figure 1D only one exemplary arrangement is shown.

[0033] As noted above, the sound processing unit 106 includes a processing module 124. The processing module 124 is configured to convert an input signal received (at one or more of the input devices 113) into an output signal for stimulating a recipient's first ear (i.e., the processing module 124 is configured to perform sound processing on the input signal received at the sound processing unit 106). In other words, one or more processors 125 are configured to execute the alternating polarity processing logic 128 in the memory 126 to convert the received input signal into an output signal 145 representing an electrical stimulation delivered to the recipient.

[0034] As further described below, the electrical stimulation signals according to the presented embodiments may include alternating polarity focused multipolar stimulation signals. Thus, the output signal 145 generated by the sound processing unit 106 represents an alternating polarity focused multipolar stimulation signal (e.g., including the commands / data used by the stimulator unit 142 to form an alternating polarity focused multipolar stimulation signal). As described elsewhere herein, the stimulator unit 142 (or possibly the alternating polarity processing logic 128) may at least temporarily track / store the polarity characteristics / attributes of the delivered focused multipolar stimulation signal such that the opposite polarity characteristics are used to generate the next focused multipolar stimulation signal. For example, the stimulator unit 142 may store one (1) bit for each stimulation channel and use this information to determine the polarity of the next alternating polarity focused multipolar stimulation signal delivered via the corresponding stimulation channel. This information for each stimulation channel will be stored because the polarity alternates in relation to the stimulation signal delivered via a given stimulation channel.

[0035] As noted, Figure 1D FIG. shows an embodiment in which the processing module 124 in the sound processing unit 106 generates an output signal. In an alternative embodiment, the sound processing unit 106 may send less processed information (e.g., audio data) to the implantable component 112, and the sound processing operations (e.g., the conversion of sound to the output signal 145) may be performed by a processor within the implantable component 112. That is, the implantable component 112, rather than the sound processing unit 106, may include a processing module similar to Figure 1D the processing module 124.

[0036] Returning to Figure 1DIn a specific example, the output signal 145 is provided to the RF transceiver 122, which transcutaneously transmits the output signal (e.g., in an encoded manner) to the implantable component 112 via the external coil 108 and the implantable coil 114. That is, the output signal is received at the RF interface circuitry 140 via the implantable coil 114 and provided to the stimulator unit 142. The stimulator unit 142 is configured to generate an electrical stimulation signal (e.g., a current signal) using the output signal for delivery to the recipient's cochlea via the stimulation channels, where each stimulation channel includes one or more stimulation electrodes / contacts 144. In this way, the cochlear implant system 102 electrically stimulates the recipient's auditory nerve cells, thereby bypassing the missing or defective hair cells that normally convert acoustic vibrations into neural activity in a manner that enables the recipient to perceive one or more components of the received sound signal.

[0037] As described, the processing module 124 generates the output signal 145, which is in turn used by the stimulator unit 142 to generate current pulses and / or electrode shorting periods that, as described below, form the alternating polarity focused multipolar stimulation signals presented herein. Thus, the processing module 124 and the stimulator unit 142 are sometimes collectively referred to herein as the "stimulation subsystem" 143, which is generally configured to generate a plurality of alternating polarity focused multipolar stimulation signals for delivery via the plurality of electrodes 144.

[0038] Generally, due to electrical stimulation, the flow of anions (-) and cations (+) is controlled by the mechanisms of the circuitry within the stimulator unit. In the stimulator unit, the cathode is considered the negative pole (-) as it emits anions (-), while the anode is the positive pole (+) as it emits cations (+). Thus, depending on the configuration of the polarity of the stimulator at a given time, the stimulator will emit either cations or anions into the body part being stimulated. In cathodal stimulation, anions (-) are emitted into the body as current flows from the cathode (-) through the tissue back to the anode (+). In anodal stimulation, cations (+) are emitted into the body as current flows from the anode (+) through the tissue back to the cathode (-).

[0039] In addition, electrical stimulation of tissue (e.g., nerve cells) requires "charge balance". That is, any charge delivered to the recipient's tissue must also be removed / withdrawn from the tissue, at least to the extent that there is a net average DC current below a predetermined threshold (e.g., approximately less than 100 nA).

[0040] As Figure 2As shown, some implantable medical devices use a biphasic stimulation signal 247 (biphasic stimulation) to ensure charge balance. In conventional biphasic stimulation, the stimulation circuit (stimulator) of the device delivers a first cathodic (-) current pulse 250, followed by a second anodic (+) current pulse 252 (or vice versa in an alternative embodiment), where the first and second current pulses are generally "balanced". That is, the first and second current pulses that form the biphasic stimulation signal are typically configured to inject substantially the same amount of charge but with opposite polarities into the tissue.

[0041] For example, as Figure 2 shown, for each biphasic stimulation signal 247, the implantable medical device generates a cathodic current pulse 250 and injects it into the electrode-tissue interface. The cathodic pulse 250 depolarizes the axons in the recipient's tissue and thus triggers an action potential (e.g., in the case of an auditory prosthesis such as the cochlear implant system 102, the cathodic current pulse is the stimulating portion that induces auditory perception).

[0042] As shown, the cathodic current pulse 250 is followed by an interphase gap (IPG) 251 (e.g., a period of time during which no stimulation signal is delivered). After the IPG 251, the implantable medical device then generates and injects an anodic current pulse 252. The anodic pulse 252 injects charge into the electrode-tissue interface to reverse any potentially damaging electrochemical processes that may have occurred at the electrode-tissue interface during the delivery of the cathodic current pulse 250. That is, the cathodic and anodic current pulses are generally "balanced" in that they each inject similar (e.g., within about 5% of each other) but opposite-polarity charges into the electrode-tissue interface. The net result is that the tissue is generally charge balanced.

[0043] As described, the anodic current pulse 252 may be followed by a short-circuit period 254 (short-circuit period) during which all of the implantable electrodes are shorted together. Generally, a biphasic stimulation pulse (i.e., two sequential current pulses with opposite polarities, such as pulses 250 and 252) produces a stimulation at the electrode-tissue interface that results in a near-zero net charge (e.g., substantially removing charge imbalance to the extent that the net average DC current is ensured to be below a predetermined threshold). As a result, the short-circuit period 254 is relatively short and can act as a safety mechanism. In conventional biphasic stimulation, the short-circuit period 254 has a predetermined length (no feedback loop).

[0044] Since the anodic current pulse 252 is configured to balance the charge injected by the cathodic current pulse 250, the anodic current pulse 252 is generated using a current source and typically requires a similar amount of energy from the implant power source as the cathodic current pulse. That is, nearly half of the power consumed by biphasic stimulation is consumed by generating the second-polarity current pulse (e.g., the anodic current pulse 252), which only removes charge from the tissue. Since in biphasic stimulation the short-circuit period 254 is relatively short, biphasic stimulation is well-suited for use with higher stimulation rate stimulation strategies / paradigms.

[0045] Nearly half of the stimulation power used in biphasic stimulation can be saved by using monophasic stimulation, in which the anodic pulse is replaced by a long electrode short-circuit period. That is, Figure 3 A monophasic stimulation signal 349 is shown, in which an implantable medical device (e.g., the cochlear implant system 102) generates only a cathodic current pulse 350 (or in an alternative embodiment, only an anodic pulse), and replaces the anodic current pulse with a long short-circuit period 354 (short-circuit period) immediately following the cathodic current pulse 350. In conventional monophasic stimulation, the short-circuit period 354 has a predetermined length (no feedback loop) configured to remove all the charge introduced by the stimulation pulse.

[0046] The advantage of monophasic stimulation is that the short-circuit period 354 does not require stimulation energy from the implantable medical device, so the stimulation power is almost half that of biphasic stimulation. However, the length of the short-circuit period 354 needs to be long enough (e.g., having a time length) to extract the injected charge and keep the average net DC current below a predetermined threshold, e.g., less than about 100 nA. In other words, the short-circuit period 354 has a time length sufficient to ensure removal of the remaining charge imbalance, at least to the extent of ensuring a net average DC current below the predetermined threshold. The disadvantage of monophasic stimulation is that the time length of the short-circuit period 354 may be very long for the charge to decay to an acceptable level, which in turn limits the use of monophasic stimulation with higher stimulation rate stimulation strategies.

[0047] As described above, biphasic stimulation and monophasic stimulation each have associated advantages and disadvantages. Specifically, although the short short-circuit period makes biphasic stimulation well-suited for use with higher stimulation rate stimulation strategies / paradigms, biphasic stimulation also consumes a large amount of power only for the purpose of charge balance. In addition, monophasic stimulation does not consume power for charge balance purposes, and long short-circuit period monophasic stimulation limits the use of monophasic stimulation with higher stimulation rate stimulation strategies.

[0048] This document presents an "alternating polarity focused multipolar stimulation (FMP) technique" that provides reduced power benefits in multipolar stimulation implementations. More specifically, with particular reference to Figures 1A-1DIn the arrangement, the cochlear implant system 102 is configured to generate an "alternating polarity focused multipolar stimulation signal (FMP)" based on one or more received sound signals. As used herein, each "alternating polarity focused multipolar stimulation signal" consists only of what is referred to as a "monopolar current pulse (monopolar pulse)", as further described below, and for each alternating polarity focused multipolar stimulation signal, the polarity characteristics of the alternating polarity focused multipolar stimulation signal alternate / reverse.

[0049] As used herein, a monopolar current pulse is a current pulse that has only a single current polarity (i.e., only a cathodic current pulse or only an anodic current pulse, with no associated balancing pulse having an opposite current polarity). Since there is no second polarity pulse, no energy / power is required to generate a second current pulse, which achieves power savings similar to monopolar stimulation.

[0050] As described above, the basic principle of electrically stimulating tissue (e.g., nerve cells) is charge balance, which means that any charge delivered to the recipient's tissue must also be removed / withdrawn from the tissue, at least to the extent that there is a net average DC current below an acceptable predetermined threshold (e.g., below approximately less than 100 nA). This principle is the basic reason why biphasic or monopolar stimulation is used for tissue stimulation in a conventional arrangement (i.e., the injected current is immediately balanced by a pulse of opposite polarity or a long short-circuit period, and the pulse of opposite polarity or the long short-circuit period withdraws substantially all of the injected charge). The techniques presented herein use only monopolar current pulses, seemingly violating these charge balance principles. However, this is not the case because the inventors have found that over time and by appropriately controlling the size of the nerve area being stimulated, alternating polarity focused multipolar stimulation will achieve a net average DC current below an acceptable predetermined threshold (e.g., below approximately less than 100 nA) without introducing stimulation artifacts.

[0051] More specifically, alternating polarity focused multipolar stimulation is DC balanced, but also leaves a small DC potential after each stimulation pulse. However, since the polarity of the subsequent pulses alternates (or at least is random), these potentials cancel out over time, resulting in zero net DC. The magnitude of the DC potential left after each stimulation is also less important, and the use of alternating polarity focused multipolar stimulation can reduce the need for series capacitors (e.g., if the DC is small, series capacitors may not be needed, as is the case with biphasic stimulation, which is not DC balanced).

[0052] In addition, as described above, monopolar pulses have approximately half the stimulation power draw of biphasic pulses because there is no second polarity phase that requires implant power. Moreover, monopolar pulses produce a lower threshold than biphasic pulses, which can further reduce the stimulation power.

[0053] The benefits of unipolar pulses are evident and as described above. However, when used for monopolar stimulation, the main drawback of unipolar pulses is that they are likely to produce unwanted sensations. Monopolar stimulation refers to a stimulation technique in which a current pulse is typically delivered via a stimulation electrode located generally adjacent to the target nerve cells, but the current returns to the stimulator / ground via one or more "remote" electrodes that are not adjacent to the target nerve cells, which creates a large amount of current spread between the adjacent electrodes. In the case of monopolar stimulation using unipolar pulses, any stimulation polarity (i.e., in-phase or out-of-phase) between adjacent electrodes affects the current flow and thus the sensation of the nerve clusters between the adjacent electrodes. Since the in-phase and out-of-phase nature of the waveform is arbitrary and difficult to control in actual mapping, this is likely to result in arbitrary and uncontrolled sensations for alternating-polarity monopolar stimulation. However, this sensation is the same for alternating-polarity focused multipolar stimulation, regardless of the polarity, with no sensation difference between the two phase cases.

[0054] In other words, since focused multipolar stimulation signals each only stimulate a narrow region of nerve cells at each stimulation channel, meaning there is little overlap between the nerve cell stimulations occurring at two adjacent stimulation channels, alternating unipolar pulses can be used with focused multipolar stimulation. Thus, alternating unipolar pulses can be in-phase or out-of-phase because they have little effect on any overlapping nerve cell regions. In contrast, monopolar stimulation has a large amount of current spread such that two adjacent stimulation channels will stimulate overlapping nerve cell regions. As a result, in the case of monopolar stimulation, alternating unipolar pulses need to be out-of-phase, otherwise the overlapping nerve cells will be overstimulated, resulting in (e.g., at the overlapping nerve cell regions) arbitrary and uncontrolled sensations. Since the phase of alternating unipolar pulses is actually difficult to control, alternating unipolar pulses are not suitable for monopolar stimulation. For example, most monopolar stimulation algorithms apply stimulation on electrodes or channels in a base-to-apex sequence (since this mimics the natural behavior of the cochlea). Thus, adjacent electrodes and channels are likely to receive two stimulation pulses that are closely connected in time, leading to the problems mentioned above. In one scenario of the monopolar case, unwanted sensations are likely to occur at a frequency corresponding to the rate of switching between the two phase cases (in-phase and out-of-phase). This is arbitrary and can be bothersome to the recipient.

[0055] In certain embodiments, the alternating-polarity focused multipolar stimulation signal may also include one or more additional short-circuit periods. However, compared to single-phase or biphasic stimulation, the short-circuit periods of alternating-polarity stimulation are reduced and may in some cases even be reduced to zero because alternating-polarity stimulation induces less DC in the stimulated electrodes.

[0056] Before describing additional details of the alternating polarity focused multipolar stimulation techniques presented herein, it is useful to explain some related terms that will be used in the following description. More specifically, certain hearing devices (e.g., cochlear implants) receive sound signals via one or more sound inputs (e.g., microphones), and a sound processor converts the one or more sound signals into one or more "channel amplitudes" at a given moment. Each channel amplitude in the one or more channel amplitudes represents the magnitude of different frequency components of the one or more sound signals at a given moment. The one or more channel amplitudes are converted into corresponding focused multipolar stimulation signals, which are delivered to the recipient via corresponding "stimulation channels".

[0057] As used herein, a "stimulation channel" is a set of electrodes that has an associated set of "weights" (fixed real numbers) used to scale the current applied via the electrodes, and a "focused multipolar stimulation signal" is the resulting current pulse delivered to the recipient via the stimulation channel. In other words, a "focused multipolar stimulation signal" is a set of current pulses that is applied via the stimulation channel and is formed by channel amplitudes (sounds) scaled by the weights set for the corresponding stimulation channel.

[0058] According to the embodiments presented herein, each weight associated with each focused multipolar stimulation signal has a "polarity attribute". A weight can be described as a positive number or "magnitude" multiplied by the polarity attribute, where the polarity attribute can have a value of negative one (-1) or positive one (+1). As used herein, a set of polarity attributes for a given focused multipolar stimulation signal refers to the polarity (positive or negative) of the real numbers (weights) used to scale the channel amplitudes when delivered via the given stimulation. Thus, the current pulses that form a given focused multipolar stimulation signal will each have a single associated polarity, but the polarities of the pulses that form a given focused multipolar stimulation signal can be different (i.e., one or more of the single-polarity pulses within a given focused multipolar stimulation signal can have a positive polarity, and one or more of the single-polarity pulses within the same given focused multipolar stimulation signal can have a negative polarity).

[0059] According to the alternating polarity focused multipolar stimulation techniques presented herein, the focused multipolar stimulation signals delivered via a given stimulation channel have an "alternating" polarity attribute. As used herein, an "alternating" polarity attribute means that when delivering the current, any two successive focused multipolar stimulation signals use weights (real numbers) of opposite polarities. The opposite polarity attribute is mathematically defined as the value of the immediately preceding polarity attribute multiplied by negative one (-1). It should be recognized that the mathematical definition does not necessarily require this step to be performed during the implementation of the techniques presented herein.

[0060] In view of the foregoing, the alternating-polarity focused multipolar stimulation technique can be explained with respect to an exemplary first stimulation channel. In this example, a first focused multipolar stimulation signal is delivered via the first stimulation channel, where the first focused multipolar stimulation signal has a first set of polarity attributes. According to the techniques presented herein, the next focused multipolar stimulation signal delivered via the first stimulation channel (referred to herein as the second focused multipolar stimulation signal) has a second set of polarity attributes that are opposite to the first set of polarity attributes (i.e., the second set of polarity attributes is mathematically the first set of polarity attributes multiplied by the value -1). The next focused multipolar stimulation signal delivered via the first stimulation channel (referred to herein as the third focused multipolar stimulation signal) has a set of polarity attributes that are the same as the first set of polarity attributes but opposite in polarity with respect to the second set of polarity attributes (i.e., the third set of polarity attributes is mathematically the second set of polarity attributes multiplied by the value -1). The next focused multipolar stimulation signal delivered via the first stimulation channel (referred to herein as the fourth focused multipolar stimulation signal) has a set of polarity attributes that are the same as the second set of polarity attributes but opposite in polarity with respect to the third set of polarity attributes (i.e., the fourth set of polarity attributes is mathematically the third set of polarity attributes multiplied by the value -1). For the focused multipolar stimulation signals delivered via the first stimulation channel, this alternating usage pattern of the alternating polarity attributes continues indefinitely. In operation, the device stores values (e.g., bits) indicating which polarity attributes should be used when generating and / or delivering the next focused multipolar stimulation signal.

[0061] Figure 4 and Figure 5 are schematic diagrams showing an exemplary use of alternating-polarity focused multipolar stimulation signals according to certain embodiments presented herein. For ease of description, reference will be made generally to the Figures 1A-1D cochlear implant system 102 of Figure 4 and Figure 5 for examples. However, as explained elsewhere herein, the alternating-polarity focused multipolar stimulation technique can be applied in various contexts and can be implemented by many different implantable medical devices or non-implantable medical devices, different implantable medical device systems or non-implantable medical device systems, etc.

[0062] Generally, Figure 4 and Figure 5 each include waveforms showing the use of alternating-polarity focused multipolar stimulation on two stimulation channels. More specifically, Figure 4 and Figure 5 each show the current through six (6) electrodes (referred to as electrode 1, electrode 2, electrode 3, electrode 4, electrode 5, and electrode 6) over a certain period of time. These six electrodes form at least two (2) overlapping stimulation channels, referred to as stimulation channel 3 (e.g., formed by electrodes 1, 2, 3, 4, and 5) and stimulation channel 4 (e.g., formed by electrodes 2, 3, 4, 5, and 6).

[0063] For ease of description, assume that in Figure 4 and Figure 5 there is a current “I” passing through the center electrode of each channel (i.e., electrode 3 for stimulation channel 3 and electrode 4 for stimulation channel 4) within each stimulation signal / frame (i.e., at the time when a current pulse is delivered via a given channel). In reality, the current magnitude value can vary across different channels and at different times depending on the incoming sound and the way the incoming sound is processed.

[0064] In addition, in Figure 4 and Figure 5 the stimulation current (current pulse) delivered via each electrode is shown using shaded bars, and the current flowing into / out of a particular electrode is indicated by the height of the bar. For ease of identification only, different shadings are used to show the current waveforms of channel 3 and channel 4. The shadings shown are not related to the waveforms that will actually be delivered via the particular electrodes.

[0065] Specifically referring to Figure 4 , an exemplary use of alternating-polarity focused multipolar stimulation is shown, where the stimulation signals delivered via stimulation channel 3 and stimulation channel 4 are “in phase”. Specifically, Figure 4 shows eight (8) focused multipolar stimulation signals / frames, referred to as focused multipolar stimulation signals 463(1) - 463(4) (delivered via stimulation channel 3) and focused multipolar stimulation signals 464(1) - 464(4) (delivered via stimulation channel 4). In operation, each of the focused multipolar stimulation signals 463(1) - 463(4) and 464(1) - 464(4) is delivered to evoke a perception (e.g., a hearing perception) in the recipient (i.e., each focused multipolar stimulation signal individually depolarizes the axons and triggers an action potential). That is, in the specific context of a cochlear implant, each of the focused multipolar stimulation signals 463(1) - 463(4) and 464(1) - 464(4) is delivered to evoke a perception of different parts of the sound / audio signal processed by the cochlear implant. As described below, two successive focused multipolar stimulation signals (e.g., focused multipolar stimulation signals 463(1) and 463(2)) delivered via the same stimulation channel together form an alternating-polarity focused multipolar stimulation because, as described above, the polarity attribute alternates / reverses between two successive focused multipolar stimulation signals.

[0066] In Figure 4In it, each focused multipolar stimulation signal 463(1)-463(4) and 464(1)-464(4) consists only of unipolar current pulses through five electrodes, with the current in the corresponding central electrode being I, the current in the two flanking electrodes being -0.5I, and the current in the two more flanking electrodes being -0.25I. As described, these specific current values are only illustrative, and in fact, the current quantity values vary over time and for different channels depending on the incoming sound and the way the incoming sound is processed. Additionally, note that the total intracochlear current is not equal to zero, and since Kirchhoff's circuit laws require the sum of all currents to be equal to zero, it is speculated that a certain amount of current can flow to / from the remote extracochlear electrodes.

[0067] As described, each focused multipolar stimulation signal 463(1)-463(4) and 464(1)-464(4) consists only of unipolar current pulses at each electrode. That is, as described above, within each focused multipolar stimulation signal, the weights (and resulting currents) associated with each electrode only have a unipolar property, but the polarity property can be different for different electrodes within the stimulation channel (i.e., one or more current pulses within the focused multipolar stimulation signal can have one polarity property, while one or more other current pulses within the same focused multipolar stimulation signal can have the opposite polarity property). Additionally, as Figure 4 shown in, for two successive focused multipolar stimulation signals delivered via a given stimulation channel, the polarity property alternates. This concept is further described below first with respect to stimulation channel 3 and then with respect to stimulation channel 4.

[0068] More specifically, the focused multipolar stimulation signal 463(1) at stimulation channel 3 has a first set of polarity properties (i.e., the stimulation channel weights are real numbers with the polarity property as previously defined, such that the resulting current pulses only have a single polarity), but the focused multipolar stimulation signal 463(2) (i.e., the next focused multipolar stimulation signal delivered via stimulation channel 3) has a second set of polarity properties opposite to the first set of polarity properties (i.e., the second set of polarity properties is mathematically the first set of polarity properties multiplied by the value -1). For example, as Figure 4 shown in, the polarity properties of electrodes 1, 2, 4, and 5 produce cathode pulses (i.e., pulses below the horizontal line as currently shown) in the stimulation signal 463(1), but the polarity properties of electrodes 1, 2, 4, and 5 all produce anode pulses (i.e., pulses above the horizontal line shown) in the focused multipolar stimulation signal 463(2). Similarly, the polarity property of electrode 3 produces an anode pulse in the focused multipolar stimulation signal 463(1), but the polarity property of electrode 3 produces a cathode pulse in the focused multipolar stimulation signal 463(2).

[0069] Whether the focused multipolar stimulation signal 463(3) (which is the third focused multipolar stimulation signal delivered via stimulation channel 3) has the first set of polarity attributes (i.e., the second set of polarity attributes multiplied by the value -1), or whether the fourth focused multipolar stimulation signal 463(4) delivered via stimulation channel 3 has the second set of polarity attributes (i.e., the first set of polarity attributes multiplied by the value -1). The alternating polarity pattern of each successive focused multipolar stimulation signal on the same stimulation channel continues indefinitely, where the current set or next set of polarity attributes is stored by the cochlear implant system 102. That is, the cochlear implant system 102 tracks the polarity of the stimulation at each stimulation channel to ensure that the next focused multipolar stimulation signal delivered via the same stimulation channel has a set of polarity attributes opposite to those of the immediately preceding focused multipolar stimulation signal within the same given stimulation channel.

[0070] In Figure 4 this specific example, the focused multipolar stimulation signals 464(1)-464(4) are implemented in the same manner as the focused multipolar stimulation signals 463(1)-463(4). Specifically, the focused multipolar stimulation signal 464(1) has the first set of polarity attributes, and the focused multipolar stimulation signal 464(2) has the second set of polarity attributes, i.e., the first set of polarity attributes multiplied by the value -1. For example, as Figure 4 shown, the polarity attributes of electrodes 2, 3, 5, and 6 all produce cathodic pulses in the stimulation signal 464(1), but the polarity attributes of electrodes 2, 3, 5, and 6 produce anodic pulses in the stimulation signal 464(2). Similarly, the polarity attribute of electrode 4 produces an anodic pulse in the focused multipolar stimulation signal 464(1), but the polarity attribute of electrode 4 produces a cathodic pulse in the focused multipolar stimulation signal 463(2).

[0071] Whether the focused multipolar stimulation signal 464(3) (which is the third focused multipolar stimulation signal delivered via stimulation channel 4) has the first set of polarity attributes, or whether the last fourth focused multipolar stimulation signal 464(4) has the second set of polarity attributes. The alternating polarity pattern of each successive focused multipolar stimulation signal on the same stimulation channel continues indefinitely, where the polarity is stored by the cochlear implant system 102. That is, the cochlear implant system 102 tracks the polarity of the stimulation at the stimulation channel to ensure that the next focused multipolar stimulation signal delivered via the same stimulation channel has a polarity opposite to that of the immediately preceding focused multipolar stimulation signal within the same given stimulation channel.

[0072] As described above, Figure 4An example of "in-phase" focused multipolar stimulation signals delivered via stimulation channel 3 and stimulation channel 4 is shown. As used herein, the reference to "in-phase" means that the polar attributes of the focused multipolar stimulation signals delivered at the two channels being discussed are the same (e.g., the first focused multipolar stimulation signal on each of stimulation channel 3 and stimulation channel 4 has the same first set of polar attributes, the second focused multipolar stimulation signal on each of stimulation channel 3 and stimulation channel 4 has the same second set of polar attributes, and so on).

[0073] Next, referring to Figure 5 , an exemplary use of alternating-polarity focused multipolar stimulation is shown, where the focused multipolar stimulation signals delivered via stimulation channel 3 and stimulation channel 4 are "out-of-phase". Figure 5 Eight (8) multipolar first stimulation signals / frames are shown in

[0074] referred to as focused multipolar stimulation signals 563(1)-563(4) (delivered via stimulation channel 3) and focused multipolar stimulation signals 564(1)-564(4) (delivered via stimulation channel 4). In operation, each of the focused multipolar stimulation signals 563(1)-563(4) and 564(1)-564(4) is delivered to evoke a perception (e.g., an auditory perception) in the recipient (i.e., each focused multipolar stimulation signal individually depolarizes an axon and triggers an action potential). For example, in the specific context of a cochlear implant, each of the focused multipolar stimulation signals 563(1)-563(4) and 564(1)-564(4) is delivered to evoke a perception of different parts of the sound / audio signal processed by the cochlear implant. Figure 5 In Figure 4 , similar to the case in

[0075] As described, each of the focused multipolar stimulation signals 563(1)-563(4) and 564(1)-564(4) consists of only unipolar stimulation pulses at each electrode. That is, as described above, within each focused multipolar stimulation signal, the weights (and resulting currents) associated with each electrode have only unipolar attributes, but the polarity attributes can be different for different electrodes within a stimulation channel (i.e., one or more current pulses within a focused multipolar stimulation signal can be anodic while one or more other current pulses within the same focused multipolar stimulation signal can be cathodic). Additionally, as Figure 5 shown in

[0076] described below, for two successive focused multipolar stimulation signals delivered via a given stimulation channel, the polarity attributes alternate. This concept is further described below first with respect to stimulation channel 3 and then with respect to stimulation channel 4. Figure 5 more specifically, the focused multipolar stimulation signal 563(1) at stimulation channel 3 has a first set of polarity attributes (i.e., the stimulation channel weights are real numbers such that the resulting current pulses have only a single polarity that is either cathodic or anodic), but the focused multipolar stimulation signal 563(2) (i.e., the next stimulation signal delivered via stimulation channel 3) has a second set of polarity attributes that are opposite to the first set of polarity attributes (i.e., the second set of polarity attributes is mathematically the first set of polarity attributes multiplied by the value -1). For example, as

[0077] shown in

[0078] the polarity attributes of electrodes 1, 2, 4, and 5 result in cathodic pulses in the stimulation signal 563(1), but the polarity attributes of electrodes 1, 2, 4, and 5 all result in anodic pulses in the focused multipolar stimulation signal 563(2). Similarly, the polarity attributes of electrode 3 result in anodic pulses in the focused multipolar stimulation signal 563(1), but the polarity attributes of electrode 3 result in cathodic pulses in the focused multipolar stimulation signal 563(2). Figure 5In this particular example, the focused multipolar stimulation signals 564(1)-564(4) are of opposite polarity to the focused multipolar stimulation signals 563(1)-563(4) (such as the so-called "antiphase" condition between channel 3 and channel 4 described previously). Specifically, the focused multipolar stimulation signal 564(1) has a second set of polarity attributes, and the focused multipolar stimulation signal 564(2) has a first set of polarity attributes (i.e., the second set of polarity attributes multiplied by the value -1). For example, as Figure 5 shown in, the polarity attributes of electrodes 2, 3, 5, and 6 all produce anodic pulses in the stimulation signal 564(1), but the polarity attributes of electrodes 2, 3, 5, and 6 all produce cathodic pulses in the stimulation signal 564(2). Similarly, the polarity attribute of electrode 4 produces a cathodic pulse in the focused multipolar stimulation signal 564(1), but the polarity attribute of electrode 4 produces an anodic pulse in the focused multipolar stimulation signal 564(2).

[0079] The third focused multipolar stimulation signal 564(3), which is delivered via stimulation channel 4, still has the second set of polarity attributes, and the last fourth focused multipolar stimulation signal 564(4) still has the first set of polarity attributes. The alternating polarity pattern of each successive focused multipolar stimulation signal on the same stimulation channel continues indefinitely, where the current polarity or the next polarity is stored by the cochlear implant system 102. That is, the cochlear implant system 102 tracks the polarity of the stimulation at the stimulation channel to ensure that the next focused multipolar stimulation signal delivered via the same stimulation channel has a polarity opposite to that of the immediately preceding focused multipolar stimulation signal within the same given stimulation channel.

[0080] Figure 5 The main difference between Figure 4 is that: Figure 4 shows "in-phase" focused multipolar stimulation signals, Figure 5 shows an example of "antiphase" focused multipolar stimulation signals delivered via stimulation channel 3 and stimulation channel 4. As used herein, the reference to "antiphase" means that the polarity attributes of the focused multipolar stimulation signals delivered at these two channels are opposite to each other (e.g., the first focused multipolar stimulation signal on stimulation channel 3 has a first set of polarity attributes, while the first focused multipolar stimulation signal on stimulation channel 4 has a second set of polarity attributes, the second focused multipolar stimulation signal on stimulation channel 3 has a second set of polarity attributes, while the second focused multipolar stimulation signal on stimulation channel 4 has a first set of polarity attributes, and so on).

[0081] As described above, according to certain embodiments presented herein, an alternating polarity focused multipolar stimulation signal can be implemented with a partial short circuit (partial short circuit period), during which all implantable electrodes 144 are "shorted" together. As used herein, a reference to "shorting" of implantable electrodes (e.g., electrode 144) means that the stimulation electrodes are connected together to the same low impedance (e.g., connected together inside the implantable medical device). Since these electrodes are connected to the same low impedance, i.e., shorted, any charge at the electrode-tissue interface is dissipated if enabled for a sufficient period of time. If implemented, the partial short circuit period has a short time length sufficient to withdraw only a portion of the residual charge from the electrode-tissue interface. That is, at the end of the partial short circuit period, residual charge remains at the electrode-tissue interface.

[0082] The embodiments presented herein have been described primarily with reference to an exemplary auditory prosthesis system (i.e., a cochlear implant system). However, as noted, it should be understood that the techniques presented herein can be implemented with a variety of other types of implantable medical devices (or systems including other types of implantable medical devices) that provide a wide range of therapeutic benefits to recipients, patients, or other users. For example, the techniques presented herein can be implemented with other auditory prostheses (e.g., acoustic hearing aids, middle ear auditory prostheses, bone conduction devices, direct acoustic stimulators, electroacoustic prostheses, other electrical analog auditory prostheses (e.g., auditory brain stimulators), etc.). The techniques presented herein can also be implemented with tinnitus treatment devices, vestibular devices (e.g., vestibular implants), visual devices (i.e., bionic eyes), sensors, pacemakers, drug delivery systems, defibrillators, functional electrical stimulation devices, catheters, seizure devices (e.g., devices for monitoring and / or treating seizure events), sleep apnea devices, electroporation devices, and the like.

[0083] Figure 6 An exemplary vestibular stimulator system 602 according to embodiments presented herein is shown. In this example, the vestibular stimulator system 602 includes an implantable component (vestibular stimulator) 612 and an external device / component 604 (e.g., an external processing device, battery charger, remote control, etc.).

[0084] The vestibular stimulator 612 includes an implant body (main module) 634, a lead region 636, and a stimulation assembly 616, all of which are configured to be implanted beneath the recipient's skin / tissue (tissue) 615. The implant body 634 generally includes an airtight sealed housing 638 in which an RF interface circuitry, one or more rechargeable batteries, one or more processors, and a stimulator unit are disposed. The implant body 634 also includes an internal / implantable coil 614, which is generally outside the housing 638 but is connected to a transceiver via an airtight feedthrough (not shown).

[0085] The stimulation assembly 616 includes a plurality of electrodes 644 disposed in a carrier member (e.g., a flexible silicone body). In this particular example, the stimulation assembly 616 includes three (3) stimulation electrodes, referred to as stimulation electrodes 644(1), 644(2), and 644(3). The stimulation electrodes 644(1), 644(2), and 644(3) serve as electrical interfaces for delivering electrical stimulation signals to the recipient's vestibular system. According to the embodiments presented herein, the vestibular nerve stimulator 602 is configured to stimulate the recipient's vestibular system using an alternating polarity focused multipolar stimulation signal as described elsewhere herein. That is, the vestibular nerve stimulator system 602 is configured to generate an alternating polarity focused multipolar stimulation signal and deliver it to the recipient via the stimulation electrodes 644(1), 644(2), and / or 644(3).

[0086] The stimulation assembly 616 is configured such that a surgeon can implant the stimulation assembly near the recipient's otolith organs through, for example, the recipient's oval window. It should be understood that this particular embodiment with three stimulation electrodes is merely illustrative, and the techniques presented herein can be used with stimulation assemblies having different numbers of stimulation electrodes, stimulation assemblies having different lengths, etc.

[0087] Figure 7 A retinal prosthesis system 701 is shown, which includes an external device 710 configured to communicate with a retinal prosthesis 700 via a signal 751. The retinal prosthesis 700 includes an implantable processing module 725, and a retinal prosthesis sensor - stimulator 790 is positioned near the recipient's retina. The external device 710 and the processing module 725 can communicate via coils 708, 714.

[0088] In an example, sensory input (e.g., photons entering the eye) is absorbed by a microelectronic array of the sensor - stimulator 790, which is mated with a glass piece 792 including, for example, an embedded microwire array. The glass can have a curved surface conforming to the inner radius of the retina. The sensor - stimulator 790 can include a microelectronic imaging device made of thin silicon, the thin silicon containing an integrated circuit system that converts incident photons into electron charges.

[0089] The processing module 725 includes an image processor 723 that is in signal communication with the sensor - stimulator 790 via, for example, a lead 788 that extends through a surgical incision 789 formed in the eye wall. In other examples, the processing module 725 communicates wirelessly with the sensor - stimulator 790. The image processor 723 processes the input from the sensor - stimulator 790 and provides control signals back to the sensor - stimulator 790 so that the device can provide an output to the optic nerve. That is, in an alternative example, the processing is performed by a component adjacent to or integrated with the sensor - stimulator 790. The charge generated by the conversion of incident photons is converted into a proportional amount of electron current that is input to a nearby retinal cell layer. The cells are excited and signals are sent to the optic nerve, thus triggering visual perception.

[0090] The processing module 725 can be implanted in a recipient and operate by communicating with an external device 710, which is, for example, a behind - the - ear unit, a pair of glasses, etc. The external device 710 can include an external light / image capture device (e.g., located in / on a behind - the - ear device or a pair of glasses, etc.), while as described above, in some examples, the sensor - stimulator 790 captures light / images and is implanted in the recipient.

[0091] According to the embodiments presented herein, the sensor - stimulator is configured to stimulate the recipient's optic nerve using alternating - polarity focused multipolar stimulation signals as described elsewhere herein. That is, the retinal prosthesis system 701 is configured to generate alternating - polarity focused multipolar stimulation signals and deliver them to the recipient.

[0092] Figure 8 is a flowchart of a method 890 according to the embodiments presented herein. The method 890 begins at 892, where a medical device system converts an input signal into a plurality of alternating - polarity focused multipolar stimulation signals. At 894, the medical device system sequentially delivers the plurality of alternating - polarity focused multipolar stimulation signals to the recipient via a first stimulation channel.

[0093] Figure 9 is a flowchart of a method 990 according to the embodiments presented herein. The method 990 begins at 992, where an implantable medical device system receives an input signal. At 994, the input signal is converted into a plurality of multipolar stimulation signals, and at 996, each of the plurality of multipolar stimulation signals is delivered to a recipient of the implantable medical device system using only unipolar stimulation pulses.

[0094] It should be understood that although specific uses of the present technology have been described and discussed above, the disclosed technology can be used with a variety of devices according to many examples of the present technology. The above discussion is not intended to imply that the disclosed technology is only suitable for implementation within a system similar to that shown in the drawings. In general, additional configurations can be used to practice the processes and systems herein, and / or some of the aspects described can be excluded without departing from the processes and systems disclosed herein.

[0095] The present disclosure describes some aspects of the inventive technology with reference to the accompanying drawings, in which only some possible aspects are shown. However, other aspects can be embodied in many different forms and should not be construed as limited to the aspects set forth herein. On the contrary, these aspects are provided to make the present disclosure thorough and complete and to fully convey the scope of possible aspects to those skilled in the art.

[0096] It should be understood that the various aspects described herein with reference to the drawings (e.g., parts, components, etc.) are not intended to limit the systems and processes to the specific aspects described. Accordingly, additional configurations can be used to practice the methods and systems herein, and / or some of the aspects described can be excluded without departing from the methods and systems disclosed herein.

[0097] According to certain aspects, a system and a non - transitory computer - readable storage medium are provided. The system is configured with hardware that is configured to perform operations similar to the methods of the present disclosure. One or more non - transitory computer - readable storage media include instructions that, when executed by one or more processors, cause the one or more processors to perform operations similar to the methods of the present disclosure.

[0098] Similarly, in the case where steps of a process are disclosed, these steps are described for purposes of illustrating the method and system and are not intended to limit the present disclosure to a particular sequence of steps. For example, these steps can be executed in a different order, two or more steps can be executed simultaneously, additional steps can be executed, and the disclosed steps can be excluded without departing from the present disclosure. In addition, the disclosed process can be repeated.

[0099] Although specific aspects are described herein, the scope of the present technology is not limited to these specific aspects. Those skilled in the art will recognize other aspects or improvements within the scope of the inventive technology. Accordingly, the specific structures, acts, or media are disclosed only as illustrative aspects. The scope of the present technology is defined by the following claims and any equivalents thereof.

[0100] It should also be understood that the embodiments presented herein are not mutually exclusive, and the various embodiments can be combined with another embodiment in any of a variety of different ways.

Claims

1. A method, comprising: Converting an input signal into a plurality of alternating - polarity focused multipolar stimulation signals; And Sequentially delivering the plurality of alternating - polarity focused multipolar stimulation signals via a first stimulation channel to a recipient.

2. The method according to claim 1, wherein each of the plurality of alternating - polarity focused multipolar stimulation signals comprises current pulses each having an associated polarity.

3. The method according to claim 1 or 2, wherein delivering the plurality of alternating - polarity focused multipolar stimulation signals to the recipient comprises: Generating a first alternating - polarity focused multipolar stimulation signal; Delivering the first alternating - polarity focused multipolar stimulation signal via the first stimulation channel to the recipient, wherein the first alternating - polarity focused multipolar stimulation signal has a first set of polarity attributes; Generating a second alternating - polarity focused multipolar stimulation signal; And Delivering the second alternating - polarity focused multipolar stimulation signal via the first stimulation channel to the recipient, wherein the second alternating - polarity focused multipolar stimulation signal has a second set of polarity attributes, the second set of polarity attributes being mathematically the same as the first set of polarity attributes multiplied by the value negative one.

4. The method according to claim 3, wherein the first alternating - polarity focused multipolar stimulation signal and the second alternating - polarity focused multipolar stimulation signal have unequal current amplitudes.

5. The method according to claim 3, wherein after delivering the second alternating - polarity focused multipolar stimulation signal to the recipient, the method further comprises: Generating a third alternating - polarity focused multipolar stimulation signal; And Delivering the third alternating - polarity focused multipolar stimulation signal via the first stimulation channel to the recipient, wherein the third alternating - polarity focused multipolar stimulation signal has the first set of polarity attributes.

6. The method according to claim 1 or 2, further comprising: Converting one or more input signals into a second plurality of alternating - polarity focused multipolar stimulation signals; And Delivering the second plurality of alternating - polarity focused multipolar stimulation signals via a second stimulation channel to the recipient.

7. The method according to claim 6, wherein the first stimulation channel and the second stimulation channel comprise one or more identical electrodes.

8. The method according to claim 1 or 2, further comprising: At least temporarily storing one or more polarity attributes associated with the first stimulation channel in association with each of the plurality of alternating - polarity focused multipolar stimulation signals.

9. The method according to claim 1 or 2, wherein converting the input signal into the plurality of alternating - polarity focused multipolar stimulation signals comprises: Converting one or more sound signals into the plurality of alternating - polarity focused multipolar stimulation signals.

10. The method according to claim 1 or 2, further comprising: Performing a partial short - circuit operation between two or more of the plurality of alternating - polarity focused multipolar stimulation signals.

11. A method, comprising: Receiving an input signal at an implantable medical device system; Converting the input signal into a plurality of multipolar stimulation signals; And Each of the plurality of multipolar stimulation signals is delivered to a recipient of the implantable medical device system using only unipolar stimulation pulses.

12. The method according to claim 11, wherein delivering each of the plurality of multipolar stimulation signals to the recipient comprises: delivering at least a first multipolar stimulation signal and at least a second multipolar stimulation signal to the recipient via a first stimulation channel; and inverting the polarity of the weights associated with the first stimulation channel between the at least first multipolar stimulation signal and the at least second multipolar stimulation signal.

13. The method according to claim 12, wherein delivering each of the plurality of multipolar stimulation signals to the recipient comprises: delivering at least a third multipolar stimulation signal and at least a fourth multipolar stimulation signal to the recipient via a second stimulation channel; and inverting the polarity of the weights associated with the second stimulation channel between the at least third multipolar stimulation signal and the at least fourth multipolar stimulation signal.

14. The method according to claim 11, 12 or 13, wherein the first stimulation channel and the second stimulation channel include one or more common electrodes.

15. The method according to claim 14, wherein the at least third multipolar stimulation signal is delivered between the at least first multipolar stimulation signal and the at least second multipolar stimulation signal.

16. The method according to claim 15, wherein the at least first multipolar stimulation signal and the at least third multipolar stimulation signal are in phase with each other.

17. The method according to claim 15, wherein the at least first multipolar stimulation signal and the at least third multipolar stimulation signal are out of phase with each other.

18. The method according to claim 12, further comprising: storing at least temporarily the polarity of the weights associated with the first stimulation channel.

19. The method according to claim 11, 12 or 13, wherein the input signal is an environmental signal.

20. The method according to claim 19, wherein the environmental signal is an audio signal.

21. The method according to claim 19, wherein the environmental signal is an optical signal.

22. The method according to claim 11, 12 or 13, wherein at least two of the plurality of multipolar stimulation signals are separated by at least one short-circuit period.

23. An implantable medical device system, comprising: one or more input elements configured to receive an environmental signal; one or more processors configured to convert a first portion of the environmental signal into a control signal representing at least a first multipolar stimulation signal and convert a second portion of the environmental signal into a control signal representing at least a second multipolar stimulation signal; and a stimulator unit configured to generate the at least first multipolar stimulation signal and the at least second multipolar stimulation signal from the control signal and sequentially deliver the at least first multipolar stimulation signal and the at least second multipolar stimulation signal to a recipient of the implantable medical device via a selected stimulation channel, wherein the at least first multipolar stimulation signal and the at least second multipolar stimulation signal have opposite polarity attributes.

24. The implantable medical device system according to claim 23, wherein the one or more processors or the stimulator unit are configured to store the polarity attribute of the at least first multipolar stimulation signal with respect to the selected stimulation channel.

25. The implantable medical device system according to claim 23, wherein the one or more input elements include a sound input element, and wherein the environmental signal is a sound signal.

26. The implantable medical device system according to claim 23, 24 or 25, wherein the one or more processors are configured to convert a third portion of the environmental signal into a control signal representing at least a third multipolar stimulation signal, and wherein the stimulator unit is configured to generate the at least third multipolar stimulation signal and deliver it to the recipient via another stimulation channel at a time point between delivering the at least first multipolar stimulation signal and delivering the at least second multipolar stimulation signal.

27. The implantable medical device system according to claim 26, wherein the selected stimulation channel and the another stimulation channel include one or more identical electrodes.

28. The implantable medical device system according to claim 26, wherein the at least first multipolar stimulation signal and the at least third multipolar stimulation signal are in phase with each other.

29. The implantable medical device system according to claim 23, 24 or 25, wherein the implantable medical device system is an auditory prosthesis system.

30. The implantable medical device system according to claim 29, wherein the auditory prosthesis system is a cochlear implant system.

31. The implantable medical device system according to claim 23, 24 or 25, wherein the implantable medical device system is a balance prosthesis system.

32. The implantable medical device system according to claim 23, 24 or 25, wherein the implantable medical device system is a retinal prosthesis system.

33. One or more non-transitory computer-readable storage media, comprising instructions that, when executed by a processor, cause the processor to: convert at least a portion of a first sound signal into a first multipolar stimulation signal; cause a stimulator unit to deliver the first multipolar stimulation signal to a recipient via a selected stimulation channel, wherein the first multipolar stimulation signal has a first set of polarity attributes; convert at least a portion of a second sound signal into a second multipolar stimulation signal; and cause a stimulator unit to deliver the second multipolar stimulation signal to the recipient via the selected stimulation channel, wherein the second multipolar stimulation signal has a second set of polarity attributes opposite to the first set of polarity attributes.

Images