WO2015137918A1

WO2015137918A1 - Batteries with integral active control apparatus and hearing assistance devices including the same

Info

Publication number: WO2015137918A1
Application number: PCT/US2014/022864
Authority: WO
Inventors: Paul Wagner; Erdal Karamuk; Chuangang LIN; Kathrin VUILLE-DIT-BILLE; Christian ZINK; Leo Den HARTOG; Dietmar POPOV
Original assignee: Phonak Ag
Priority date: 2014-03-10
Filing date: 2014-03-10
Publication date: 2015-09-17

Abstract

Batteries with integral active control apparatus and hearing assistance devices including the same.

Description

BATTERIES WITH INTEGRAL ACTIVE CONTROL APPARATUS AND HEARING ASSISTANCE DEVICES INCLUDING THE SAME

BACKGROUND

1 . Field

The present inventions relate generally to hearing instruments and hearing instrument batteries.

2. Description of the Related Art

Extended wear hearing devices are configured to be worn continuously, from several weeks to several months, inside the ear canal. Such devices may be miniature in size in order to fit entirely within the ear canal and are configured such that the receiver fits deeply in the ear canal in proximity to the tympanic membrane. Batteries such as metal-air batteries are an integral part, i.e., a non-removable part, of extended wear hearing instruments. As such, extended wear hearing instruments must consume power at rates that are far lower than daily wear hearing instruments which employ metal-air batteries that last approximately one week.

Conventional metal-air batteries employed in hearing instruments are mechanically passive devices that include a cathode assembly, with an air port through which oxygen from the outside environment flows into the battery, and an anode can with anode material. The anode material may consist of a metal powder (e.g., zinc powder) and an aqueous electrolyte solution. The oxygen that passes through the air port chemically reacts with the metal ions dissolved in the electrolyte to generate electrical current. The reaction rate in conventional metal-air batteries is passively determined by the internal geometry and materials of the battery, the availability of oxygen and unreacted metal ions, and the loading impedance from the external electrical circuit.

SUMMARY

The present inventors have determined that the conventional metal-air batteries employed in hearing instruments are susceptible to improvement. For example, the present inventors have determined that there are a number of aspects of metal-air batteries, and the operation thereof, that may be improved by integrating active control apparatus into the cathode assemblies and/or other portions of the batteries. Such active control apparatus include of one or more devices, such as a microelectromechanical systems ("MEMS") device, a sensor (including MEMS sensors) and/or an application-specific integrated circuit ("ASIC") or other control circuitry, that controls one or more aspects of the operation or use of the battery. Different batteries may include different active control apparatus, and some batteries may include more than one active control apparatus.

A battery in accordance with at least one of the present inventions includes a cathode assembly with an integral active gas diffusion barrier that selectively controls gas inflow and outflow to and from the cathode assembly in response to control signals. The active gas diffusion barrier may, for example, be a MEMS device that is selectively movable between open and closed states and various partially open states therebetween. The present inventions also include hearing assistance devices that include such a battery. There are a variety of advantages associated with active gas diffusion control as compared to passive gas diffusion control. Conventional passive gas diffusion barriers limit the diffusion of oxygen and water molecules in and out of the battery, thereby reducing the likelihood that the battery will dry our or that excessive moisture and/or CO2 may enter the battery from the outside environment during use. There may, however, be instances where such a passive barrier is less than optimal. For example, the reduced rate of oxygen inflow can lead to an inability of the hearing instrument to operate at higher output powers as well as increased distortion. An active gas diffusion barrier, on the other hand, allows the present battery to selectively increase, decrease or block the flow of gas in and out the battery in response to, for example, measured operating conditions.

A battery in accordance with at least one of the present inventions includes an integral sensor. In at least some implementations, the integral sensor may be part of the cathode assembly. Exemplary sensors that may be integrated into cathode assemblies and/or other portions of the battery include, but are not limited to, acoustic sensors, pressure sensors and chemical sensors. The present inventions also include hearing assistance devices that include such a battery. There are a variety of advantages associated with such integrated sensors. For example, the sensors may be used for quality control testing at the time of manufacture and to determine battery capacity when the associated hearing assistance device is in use.

A battery in accordance with at least one of the present inventions includes an integral ASIC or other control circuitry. The integral ASIC or other control circuitry may, in at least some implementations, be integrated into the cathode assembly of the batteries. By way of example, but not limitation, such circuitry may be used to facilitate the addition of energy to the battery that is supplied by a solar cell or other energy harvesting device, to disconnect the battery output in low voltage situations thereby preventing battery damage and/or to facilitate the connection two or more batteries in parallel. The present inventions also include hearing assistance devices that include such a battery.

A method of operating a metal-air battery, which has anode material and a cathode assembly, in accordance with at least one of the present inventions includes the steps of monitoring voltage of the battery with control circuitry that is an integral part of the cathode assembly as current flows from the battery, and discontinuing current flow from the battery, regardless of actual loading impedance, with the control circuitry in response to a determination by the control circuitry that the monitored battery voltage is below a predetermined threshold voltage. There are a variety of advantages associated with such a method. For example, discontinuing current flow prevents the metal-air battery from being over-discharged, a condition where the battery will start to chemically consume the catalyst that results in irreversible damage to the battery

BRIEF DESCRIPTION OF THE DRAWINGS

Detailed descriptions of the exemplary embodiments will be made with reference to the accompanying drawings.

FIG. 1 is a side view of a battery in accordance with one embodiment of a present invention.

FIG. 2 is a perspective view of the battery illustrated in FIG. 1 .

FIG. 3 is a section view of a portion of the battery illustrated in FIG. 1 .

FIG. 4 is an end view of the battery illustrated in FIG. 1 . FIG. 5 is a section view taken along line 5-5 in FIG. 4 showing an exemplary gas diffusion barrier in an open state.

FIG. 6 is a section view showing the gas diffusion barrier illustrated in FIG. 5 in a closed state.

FIG. 7 is an end view of a battery in accordance with one embodiment of a present invention.

FIG. 8 is a section view of a battery in accordance with one embodiment of a present invention.

FIG. 9 is a plan view of a portion of the battery illustrated in FIG. 8.

FIG. 10 is a section view of a portion of a battery in accordance with one embodiment of a present invention.

FIG. 11 is an end view of a battery in accordance with one embodiment of a present invention.

FIG. 12 is a section view taken along line 12-12 in FIG. 11 .

FIG. 13 is a block diagram showing the battery illustrated in FIGS. 11 and 12 receiving energy from an energy harvesting device.

FIG. 14 is an end view of a battery in accordance with one embodiment of a present invention.

FIG. 15 is a section view taken along line 14-14 in FIG. 15.

FIG. 16 is a block diagram of the battery illustrated in FIGS. 14 and 15.

FIG. 17 is a block diagram of a battery in accordance with one embodiment of a present invention.

FIG. 18 is an exploded perspective view of a hearing device in accordance with one embodiment of a present invention.

FIG. 19 is a perspective view of a portion of the hearing assistance device illustrated in FIG. 18.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

The following is a detailed description of the best presently known modes of carrying out the inventions. This description is not to be taken in a limiting sense, but is made merely for the purpose of illustrating the general principles of the inventions. To that end, the present inventions may be embodied in a wide variety of batteries and hearing assistance devices including such batteries. Various aspects of the batteries (e.g., size, shape, materials) may vary so as to permit their use in a variety of hearing assistance devices.

As illustrated in FIGS. 1 -3, an exemplary battery 100 in accordance with one embodiment of a present invention has an anode can 102 (or "battery can") that holds the anode material and cathode assembly. In particular, the anode can 102 includes an anode portion 102a for anode material 104 and a cathode portion 102b for a cathode assembly 108. The exemplary anode can 102 is also provided with an inwardly contoured region 102c (or "neck") that defines an external retention ledge 102d, i.e., a retention ledge that is accessible from the exterior of the anode can, at the anode/cathode junction. The cathode portion 102b includes a crimped region 106. The inwardly contoured region 102c and retention ledge 102d are associated with the battery assembly process. To that end, the inwardly contoured region 102c defines a longitudinally extending gap that is sufficiently sized to receive crimp tooling. The inwardly contoured region 102c and retention ledge 102d may be omitted in other implementations.

An acoustic assembly of a hearing assistance device (e.g., acoustic assembly 306 in FIG. 19) may be mounted to the battery 100 and, in the illustrated embodiment, the anode can 102 is provided with an acoustic assembly support surface 110 which has a shape that corresponds to the shape of the adjacent portion of the acoustic assembly. The support surface 1 10 may in some instances, including the illustrated embodiment, be a relatively flat, recessed area defined between side protrusions 1 12 and a lateral end protrusion 1 14. The protrusions 1 12 and 1 14 align the acoustic assembly relative to the battery and also shift some of the battery volume to a more volumetrically efficient location. In other implementations, the acoustic assembly support surface 110 and protrusions 1 12 and 1 14 may be omitted. The battery 100 is electrically connected to the acoustic assembly (e.g., to the flexible circuit) by way of anode and cathode wires 1 16 and 1 18. The battery may, in other implementations, be connected to a similar flexible circuit via tabs (not shown) of the flexible circuit that attach to the battery. In still other implementations, the anode and cathode wires 116 and 118 may be omitted and replaced by anode and cathode contacts on the cathode assembly. The exemplary battery 100 is a metal-air battery and, therefore, the anode material 104 is a metal. The metal in the illustrated embodiment is zinc. More specifically, the anode material 104 may be an amalgamated zinc powder with organic and inorganic compounds including binders and corrosion inhibitors. The anodic material 104 also includes the electrolyte, typically an aqueous solution of potassium hydroxide (KOH) or sodium hydroxide (NaOH). Other suitable metals include, but are not limited to, lithium, magnesium, aluminum, iron and calcium as anode material for metal- air battery. Other battery chemistries, such as lithium primary, lithium-ion, silver zinc, nickel-metal-hydride, nickel zinc, nickel cadmium, may be used as the power source.

The exemplary cathode assembly 108, which is carried within the cathode portion 102b of the anode can 102 and is insulated from the anode can by the electrically insulating grommet 124, includes a cathode base 126 and a cathode sub-assembly 128. The exemplary cathode base 126, which may be formed from a conductive material such as nickel plated stainless steel, is generally cup-shaped and includes a side wall 130, an end wall 132 and an air port 134 that extends through the end wall. The base may be flat, annual or some other shape in other embodiments. The insulating grommet 124 has a first portion 136 that is positioned between the cathode portion 102b of the anode can 102 and the cathode base 126, and a second portion 138 that is positioned between the cathode portion 102b and the cathode subassembly 128. The grommet second portion 138 presses the cathode subassembly 128 into the cup-shaped cathode base 126. The grommet 124 also includes an aperture 140, which is aligned with a corresponding aperture 142 in the anode can 102, that exposes the base end wall 132 for electrical connection thereto and exposes the air port 134 to the atmosphere. The can aperture 142 is adjacent to the crimped region 106. The insulating grommet 124 is compressed against the cathode base 126 by the crimp 106 to create a seal. Suitable electrically non-conductive materials for grommet 124 include, but are not limited to nylon and other chemically compatible thermoplastics and elastomers.

The illustrated cathode sub-assembly 128 broadly represents several layers of materials known in the battery art. To that end, and although the present inventions are not limited to the illustrated embodiment, air (oxygen) reaches the cathode sub-assembly 128 by way of the air port 134. A cathode catalyst 146 facilitates oxygen reduction in the presence of electrons provided by a metallic mesh with the production of hydroxyl ions which react with the zinc anode. Cathode catalyst 146 may contain carbon material. Embedded in the cathode catalyst 146 is a current collector (not shown) that may be composed of a nickel mesh. The cathode current collector is electrically connected to the metal cathode base 126. A separator or "barrier layer" (not shown) is typically present to prevent zinc particles from reaching the catalyst 146 while allowing the passage of hydroxyl ions through it.

The cathode assembly 108, as well as the other cathode assemblies described herein, also includes integrated control apparatus. Such control apparatus may consist of one or more devices, such as a microelectromechanical systems ("MEMS") device, a sensor (including MEMS sensors) and/or an application-specific integrated circuit ("ASIC"). As used herein, the words "integral" and "integrated" are used to denote structures that are part of the cathode assembly by virtue of being mounted directly on and secured to, or embedded within, other portions of the cathode assembly. The integrated control apparatus in the cathode assembly 108 is an integral active gas diffusion barrier 144 (or "active GDB") that selectively controls gas inflow and outflow to and from the cathode assembly in response to control signals. The control signals may be based on one or more control parameters such as, for example, current draw. The control parameters may be measured by the associated hearing assistance device or by the battery itself. The control signals cause the active GDB 144 to allow sufficient oxygen to pass into the battery to support the required current draw of the battery while limiting water loss from the battery. To that end, the active GDB 144 has a fully open state, a fully closed state, and a plurality of partially open states therebetween. The active GDB 144 is described in greater detail below with reference to FIGS. 4- 6.

The exemplary anode can 102 is defined by a wall 150 that, in some implementations, may be a multi-layer structure that includes an inner layer 152 and a outer layer 154. The inner layer 152 is formed from a material that has strong hydrogen overpotential. For example, the inner layer 152 may be an oxygen-free copper that forms a surface alloy which inhibits oxidation and reducing reactions with the zinc inside the anode can 102. Other suitable metals for the inner layer include tin and cadmium. The structural layer 154, which defines the majority of the thickness of the wall 150, provides the structural support for the anode can 102. The structural layer 154 in the illustrated embodiment is sufficiently ductile to allow the portions of the anode can 102 to be crimped. Suitable materials for the structural layer include, but are not limited to, nickel, nickel-cobalt, and nickel alloys. In some implementations, the structural layer 154 is the outer layer. In others, a thin silver or gold layer (or "silver flash" or "gold flash") 156 may be located on the exterior surface of the nickel layer 154. The silver or gold layer 156 inhibits nickel release from the anode can 102 and aids in presenting a surface that is easier to form electrical connections to with solder than does, for example, nickel.

As noted above, the exemplary active GDB 144 is an integral part of the cathode assembly 108. To that end, and referring to FIGS. 4-6, the active GDB 144 is mounted to the end wall 132 of the conductive base 126 over the air port 134. In some instances, the active GDB 144 may be formed separately from the conductive base 126 and then secured to the end wall 132, and may be formed directly on the conductive base in other instances. The exemplary active GDB 144 is an electrically controllable device that includes a substrate 158 (e.g., a silicon substrate) with an air port 160 that is aligned with the air port 134, a movable membrane 162 (e.g., a nitride membrane) with a plurality of apertures 164 that is suspended over the substrate to form an air channel 166 that connects the air port 160 to the apertures 164, and a pair of electrodes 168 and 170. Electrode 168 is on the movable membrane 162 and electrode 170 is on the substrate 158, thereby creating a parallel-plate capacitor. The movable membrane 162 remains in the open state illustrated in FIG. 5 unless a DC bias voltage (e.g., 1 .4V) is applied across the electrodes 168 and 170. The application of the bias voltage to the electrodes 168 and 170 causes the movable membrane 162 to move to the closed position illustrated in FIG. 6. This prevents air flow between the air port 160 and the apertures 164 and, accordingly, closes the active GDB 144 and prevents air flow to the cathode sub-assembly 128 by way of the air port 134. Voltages of less than 1 .4V may be employed to partially close the active GDB 144, thereby reducing air flow to various flow rates without completely preventing it. During periods of shipping and storage, which may last up to one year, the battery 100 may be stored under oxygen-free and dry conditions. Alternatively, or in addition, the cathode assembly 108 may be sealed with the sealing tape used in conjunction with conventional zinc-air batteries.

The voltage may be supplied to the active GDB 144 in a variety of ways. In the illustrated embodiment, for example, the active GDB substrate 158 includes integrated electronic circuitry 172 that is connected to the electrode 168 by a conductor 174. The electrode 170 is connected to ground by conductor 176. The integrated electronics 172 converts an input signal into the DC bias voltage applied to the electrodes 168 and 170. The integrated electronic circuitry 172 may include or be connected to a pad that receives the input signal. The integrated electronic circuitry 172 may also be configured to determine the actual battery current and derive the DC bias voltage as a function of the actual battery current.

In some instances, the cathode wire 118 will be connected to the integrated circuitry 172, instead of the illustrated direct connection to the current collected at the cathode base 126, and the integrated circuitry will be connected to the cathode base. Here, integrated electronic circuitry 172 may include a switch, such as the switch 204 described below with reference to FIG. 17, which is in series between the cathode wire 118 and the cathode base 126. The integrated electronic circuitry 172 is configured to open the switch, thereby preventing current draw, when the voltage drops below a predetermined level (e.g., 0.7V) to prevent deep discharge and damage to the battery.

In other implementations, the control signal for the active GDB may be supplied by the associated hearing device. To that end, and referring to FIG. 7, battery 100a is essentially identical to battery 100 and similar elements are represented by similar reference numerals. For example, the exemplary active GDB 144a is an integral part of the cathode assembly 108a. Here, however, the cathode assembly 108a does not include integrated electronic circuitry to control the operation of the active GDB 144a. Instead, contacts 178 and 180 are connected to the conductors 174 and 176. The hearing device applies the DC bias voltage across the electrodes 168 and 170 by way of the contacts 178 and 180.

Sensors are another type of control apparatus that may be integrated into a cathode assembly. Such sensors include, but are not limited to, sensors that transmit and receive acoustic signals, sensor that sense pressure in various regions of the battery, and chemical sensors. Sensors may be integrated into cathode assemblies, such as the cathode assemblies described above with reference FIGS. 1 -7, that include an active GDB, and the particular sensors described below may be employed in the cathode assemblies described above with reference to FIGS. 1 -7. Sensors may also be integrated into cathode assemblies that include a passive GDB, as is described below with reference to, for example, FIGS. 8 and 9.

As illustrated for example in FIGS. 8 and 9, battery 100b is substantially similar to battery 100 and similar elements are represented by similar reference numerals. Here, however, the cathode assembly 108b includes a passive GDB 182 and a sensor assembly 184 that is mounted under the cathode base 126b. Although other aspects of the battery may be measured or sensed, the exemplary sensor assembly 184 is configured to take measurements that may be used to determine how much unconsumed anode material (e.g., unconsumed metal such as zinc) remains in the battery 100b. The exemplary sensor assembly 184 includes a substrate 186 (e.g., a silicon substrate) with an air port 188, a sensor 190, integrated electronics or other control circuitry 192, and plurality of contacts 194. The sensor assembly 184 may be powered by the battery 100b itself. The substrate 186 is larger than the opening 134b in the cathode base end wall 132b, and is secured to the cathode base end wall such that an air-tight seal is established between the two. This limits gas flow in and out of the battery 100b to flow through the air port 188. The sensor 190 may be, for example, a MEMS or piezoelectric sensor. In either case, the sensor 190 may include a movable structure (e.g., a membrane) that is periodically actuated to transmit high frequency acoustic pulses 196 into the anode material 104, sense the arrival of return acoustic pulses 198, and measure the amount of time that elapses between the transmission and return. The dimensions of the anode can 102 are known, as are the respective (and different) speeds though which the acoustic pulses will travel through zinc and zinc-oxide or other metals and metal-oxides. As such, the amount of time that elapses between the transmission and return of the pulses can be used to calculate the percentage of total material that is zinc which has yet to be consumed and, therefore, the amount of zinc that has yet to be consumed.

This information may be used by the integrated electronics or other control circuitry 192 and/or the control circuitry of the associated hearing assistance device to estimate how much longer the battery will last and, for example, to provide the user with a "low battery" warning when the battery's capacity reaches a predetermined threshold such as 3-5 days. In those instances where the control circuitry 192 of the battery makes the determination, the control circuitry will send a "low battery" signal to the hearing assistance device. The warning may be in the form of an audible warning from the hearing assistance device receiver.

In other implementations, the sensor assembly may be configured such that the sensor is located somewhere other than on the substrate that is integrated into the cathode assembly. To that end, the exemplary battery 100c illustrated in FIG. 10 is essentially identical to the battery 100b but for the sensor and configuration of the control circuitry. For example, battery 100c includes a sensor assembly (with a substrate, control circuitry, contacts, etc.) that is integrated into the cathode assembly in the manner described above with reference to FIGS. 8 and 9. Here, however, the sensor 190c is not an acoustic pulse transmitter/detector that is located on the assembly substrate and, instead, is a microscopic MEMS pressure sensor 190c that is located in the air bubble 105 at the end of the anode portion 102a. Pressure sensor 190c may be connected to the control circuitry by wires 200, or by a single wire and the anode can 102. The pressure sensor 190c takes advantage of the fact that the volume of material within the anode portion 102a changes as the anode material 104 is consumed. In the exemplary context of zinc anode material, zinc-oxide replaces the zinc as the zinc is consumed and zinc-oxide occupies a greater volume than does zinc. The air bubble 105 is, therefore, compressed and air bubble pressure increases as the zinc is consumed by battery operation. As such, the pressure measured in the air bubble 105 may be used to calculate the percentage of zinc that is yet to be consumed. The information may be used in the manner described above to provide a "low battery" warning to the user.

In another implementation (not shown) where the sensor assembly (e.g., substrate, control circuitry, contacts, etc.) is integrated into the cathode assembly and the sensor is located somewhere other than on the substrate, a small insulated zinc wire is connected to the control circuitry on the substrate and routed through the interior of battery to the bottom of the battery can anode portion, i.e., the end opposite the cathode assembly. A portion of the insulation is removed to form an exposed zinc wire segment slightly up from the bottom of the anode can. The exposed portion of the zinc wire will be consumed along with the zinc anode material when the zinc utilization front will reaches the exposed portion of the wire, which occurs when almost all of the zinc has been consumed. The consumption of the exposed zinc wire material changes the resistance of the wire, which can be detected by the control circuitry and converted to a digital output signal that can be used to generate a low battery warning.

Another type of control apparatus that may be integrated into a cathode assembly is charging circuitry that controls the supply power to the battery from one or more sources external to the battery. For example, an energy harvesting device such as a small solar cell may be mounted on the hearing instrument to harvest energy from the ambient environment. To that end, and referring to FIGS. 11 -13, the exemplary battery 100d is substantially similar to battery 100b and similar elements are represented by similar reference numerals. For example, the exemplary battery 100d has a cathode assembly 108d which includes a cathode base 126 with an end wall 132 and an opening 134b, and a passive GDB 182. Here, however, the cathode assembly 108d includes a charging assembly 184d that is mounted under the cathode base 126d. The exemplary charging assembly 184d includes a substrate 186d with an air port 188, integrated electronics or other control circuitry 192d, and plurality of contacts 194. The substrate 186d is larger than the opening 134d, and is secured to the cathode base end wall such that an air-tight seal is established between the two. This limits gas flow in and out of the battery 100d to flow through the air port 188. The integrated electronics 192d convert variable power coming from an energy harvesting device 10 (FIG. 13) into a form that can be added directly to the battery. To keep the routing efficient, there are four contacts 194, two for connection to the energy harvesting device 10 and two for connection to hearing assistance device electronics. An anode wire (e.g., anode wire 116 in FIG. 2) is also connected to the hearing assistance device electronics. Alternatively, an anode wire may be connected to one of the contacts 194 and re-routed from there to the hearing assistance device electronics by way of a second wire connected to a contact.

The harvesting of energy from the ambient environment extends the life of the battery 100d, as compared to an otherwise identical metal-air battery that lacks the present cathode assembly 108d, even in those instances where the energy harvesting apparatus produces small amounts of energy that are insufficient to fully charge a continuous wear hearing instrument battery. For example, a high efficiency 4.5 mm x 2.5 mm GaAs solar cell can produce a maximum of 3 mW in direct sunlight. Even assuming that the solar cell generated only 1 % of this power due to the low light level when mounted in the ear on an extended wear hearing instrument, the 30 μ\Λ generated would extend the lifetime of the battery. In those instances where the associated hearing device (e.g., the hearing device 300 described below) consumes 35-60 μ\Λ , depending on the acoustic environment, the battery lifetime could be almost doubled. The present inventions are also not limited to harvesting energy with solar cells. Other energy harvesting apparatus such as, for example, apparatus that harvest mechanical energy associated with movement and vibration and apparatus that harvest energy associated with temperature differences that may arise when the user of the hearing instrument takes a shower or walks in the cold, may be employed.

In other implementations, control apparatus that is integrated into a cathode assembly may include one or more sensors, but lack control circuitry. Such sensors may be used, for example, during the battery assembly process for quality control purposes as is discussed below. One example of a battery that includes such control apparatus is generally represented by reference numeral 100e in FIGS. 14-16. Battery 100e is essentially identical to battery 100d and similar elements are represented by similar reference numerals. For example, the battery 100e includes a cathode assembly 108e with a conductive cathode base 126e, cathode sub-assembly 128, and a sensor assembly 184e with a substrate 186e. Here, however, the cathode base 102e is cylindrical and the sensor assembly 184e includes a substrate 186e that itself defines a passive GDB 182e. The passive GDB 182e is formed by a plurality of apertures (e.g., narrow plasma etched vias) that extend through the substrate 186e. The sensor assembly 184e also includes a chemical sensor 200 (e.g., a thin film electrolyte sensor) and/or a pressure sensor 202 (e.g., a thin film pressure sensor) as well as a plurality of contacts 194 on the substrate. Each sensor 200 and 202 is connected to the ground contact and to its own respective contact. The chemical sensor 200 may be used to detect internal leakage or cathode salting. The pressure sensor 202 may be used to measure the crimp compression force (sometimes referred to as "sealing pressure"). Crimp compression force that is too low can lead to electrolyte leakage, while crimp compression force that is too high can lead to wrinkling or crackling of the cathode sub-assembly 128. The appropriate contacts may be probed during factory testing which is advantageous because the although leakage, salting, and improper crimp compression force can cause batteries to fail prematurely, these defects cannot be cost-effectively identified using conventional methods.

Another type of control apparatus that may be integrated into a cathode assembly is battery protection circuitry that controls the flow power from the battery to avoid battery damage. To that end, the exemplary metal-air battery 10Of illustrated in FIG. 17 includes a cathode assembly 108e with integrated electronics or other control circuitry 192f that has a switch 204 (e.g., an FET switch) in series with the power output contact 194. If the control circuitry 192f detects that the battery voltage is below a predetermined threshold voltage (e.g., below 0.7 V), it opens the switch 204, thereby reducing the current flow out of the battery to 0 μΑ. This occurs regardless of the actual loading impedance from the attached hearing assistance electronic circuitry. Such action can prevent the metal-air battery from being over-discharged, a condition where the battery will start to chemically consume the catalyst, resulting in irreversible damage to the battery. When the battery returns to normal battery voltage, i.e., when the control circuitry 192f detects that the battery voltage is above the threshold voltage, the switch 204 will close, thereby restarting the flow of current out of the battery and turning the hearing instrument (or other associated power consuming device) back on. Alternatively, or in addition, the control circuitry 192f may include control logic that, in combination with the switch 204, allows two of the batteries 10Of to be wired in parallel within a single hearing instrument. The switches 204 would insure only a single battery is actively connected to the loading circuit at any given time. For example, one battery may be activated after another has consumed all of its anode material or has failed prematurely. It should also be noted that battery protection circuitry and switch may be incorporated into the batteries described above.

One example of a hearing assistance device that may include the present batteries is the completely in the canal (or CIC) hearing device generally represented by reference numeral 300 in FIG. 18 and 19. Hearing device 300 consists of a core 302, which has one of the batteries described above (e.g., battery 100) and a pair of seals 304 that support the core 302 within the ear canal bony portion. In addition to the battery, the core 302 includes an acoustic assembly 306 with a microphone 308, a receiver 310 and a flexible circuit 312. The exemplary flexible circuit 312 includes an integrated circuit or amplifier 314 and other discreet components 316, such as a sound generator 317 that supplies a "low battery" signal to the receiver 310, on a flexible substrate 318. The acoustic assembly 306 is encased by encapsulant 320. A contamination guard 322 abuts the microphone. A handle 324 may also be provided. Additional details concern this type of hearing assistance device may be found in U.S. Pat. Pub. No. 2013/0129127, which is incorporated herein by reference.

Although the inventions disclosed herein have been described in terms of the preferred embodiments above, numerous modifications and/or additions to the above-described preferred embodiments would be readily apparent to one skilled in the art. By way of example, but not limitation, the inventions include any combination of the elements from the various species and embodiments disclosed in the specification that are not already described. It is intended that the scope of the present inventions extend to all such modifications and/or additions and that the scope of the present inventions is limited solely by the claims set forth below.

Claims

We claim:

1 . A battery, comprising:

a battery can including an anode portion and a cathode portion; anode material within the battery can anode portion; and a cathode assembly, within the battery can cathode portion, including integral active control apparatus.

2. A battery as claimed in claim 1 , wherein

the cathode assembly includes an air port; and

the integral active control apparatus comprises an active gas diffusion barrier that control gas flow through the air port.

3. A battery as claimed in claim 2, wherein

the active gas diffusion barrier comprise a MEMS device.

4. A battery as claimed in any one of claims 2 to 3, wherein

the integral active control apparatus includes circuitry that controls operation of the active gas diffusion barrier.

5. A battery as claimed in claim 1 , wherein

the integral active control apparatus comprises a sensor assembly that senses a characteristic of the anode material that is representative of the amount of unused anode material.

6. A battery as claimed in claim 5, wherein

the sensor assembly includes a substrate, control circuitry carried by the substrate, and a movable structure carried by the substrate that transmits high frequency acoustic pulses into the anode material and senses the arrival of return acoustic pulses.

7. A battery as claimed in claim 5, wherein

a gas bubble is located within the anode can; and the sensor assembly includes a substrate, control circuitry carried by the substrate, and a pressure sensor located within the gas bubble and operably connected to the control circuitry.

8. A battery as claimed in claim 1 , wherein

the integral active control apparatus comprises charging circuitry that is configured to supply power from an external device to the battery.

9. A battery as claimed in claim 1 , wherein

the battery can cathode portion is crimped; and

the integral active control apparatus comprises a pressure sensor that senses crimp compression force.

10. A battery as claimed in claim 1 , wherein

the integral active control apparatus comprises a chemical sensor.

11 . A battery as claimed in claim 1 , wherein

the integral active control apparatus comprises a power output contact, a switch that is in series with the power output contact, and control circuitry that opens the switch in response to a predetermined battery voltage.

12. A battery as claimed in any one of claims 1 to 11 , wherein

the integral active control apparatus includes a substrate and at least one electrical contact that is carried by the substrate and accessible from outside the battery.

13. A battery as claimed in any one of claims 1 and 5 to 12, wherein the integral active control apparatus a substrate and a passive gas diffusion barrier defined by a plurality of apertures that extend through the substrate.

14. A battery as claimed in claim 1 , wherein the integral active control apparatus comprises one or more of a MEMS device, a piezoelectric device, a sensor and an ASIC.

15. A hearing assistance device, comprising:

a battery as claimed in any one of claims 1 to 14; and an acoustic assembly, including a receiver and a microphone, operably connected to the battery.

16. A method of operating a metal-air battery that includes anode material and a cathode assembly, the method comprising the steps of:

monitoring voltage of the battery with control circuitry that is an integral part of the cathode assembly as current flows from the battery; and discontinuing current flow from the battery, regardless of actual loading impedance, with the control circuitry in response to a determination by the control circuitry that the monitored battery voltage is below a predetermined threshold voltage.

17. A method as claimed in claim 16, wherein

the control circuitry includes a switch; and

the step of discontinuing current flow from the battery comprises opening the switch.

18. A method as claimed in claim 16, further comprising the step of: restarting current flow from the battery in response to a determination by the control circuitry that the monitored battery voltage is above the predetermined threshold voltage.