Systems and methods related to implantable medical devices

Abstract

In one embodiment, a method includes obtaining a measurement representative of an electrical impedance within a fluid channel of an implantable medical device; and processing the measurements to determine whether the implantable medical device is perfused for implantation in a recipient. The implantable medical device may include: an implantable drug reservoir having a loading port for receiving a drug solution; a drug delivery lumen having at least one release port and configured to be implanted within a recipient; and an intermediate drug lumen extending from the implantable drug reservoir to the drug delivery lumen to form a fluid path between the loading port and the at least one release port. The implantable medical device is configured to be infused with a drug prior to implantation in a recipient. The fluid path is electrically discontinuous in the absence of the conductive solution.

Description

Cross Reference to Related Applications

[0001] This patent application claims priority to U.S. Provisional Patent Application 63 / 534,216, filed August 23, 2023, which is incorporated by reference herein in its entirety. TECHNICAL FIELD

[0002] The present disclosure relates to systems and methods for delivering a drug to an implantable medical device of a recipient. BACKGROUND

[0003] Medical devices have provided a wide range of therapeutic benefits to recipients in recent decades. Medical devices can include internal or implantable components / devices, external or wearable components / devices, or a combination thereof (e.g., a device with an external component that communicates with an implantable component). 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 improvement functions and / or recipient monitoring.

[0004] The types of medical devices, and the range of functions performed by them, have increased over the years. For example, many medical devices, sometimes referred to as “implantable medical devices,” now often include one or more instruments, apparatus, sensors, processors, controllers, or other functional mechanical or electrical components that are permanently or temporarily implanted into a recipient. These functional devices typically are used to diagnose, prevent, monitor, treat, or manage a disease / injury or symptom thereof, or study, replace or modify an anatomical structure or a physiological process. 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

[0005] According to a first embodiment, a method includes obtaining a measurement value representative of an electrical impedance within a fluid passageway of an implantable medical device, and processing the measurement value to determine whether the implantable medical device is primed for implantation into a recipient.

[0006] According to a second embodiment, a method includes measuring an electrical impedance of a drug solution contained by a fluid lumen of an implantable medical device, wherein the fluid lumen extends between a loading port and at least one release port in the implantable medical device, and determining from the electrical impedance when the fluid lumen is primed with the drug solution.

[0007] According to a third embodiment, a non-transitory computer-readable storage medium includes computer-readable instructions stored thereon for causing a computing system to: determine an electrical impedance of a drug solution in a medical device based on measurements obtained from the medical device; and determine whether an obstruction is impeding diffusion of a therapeutic substance within the drug solution based on the electrical impedance of the drug solution.

[0008] According to a fourth embodiment, an implantable drug delivery device includes: an implantable drug reservoir, wherein the implantable drug reservoir has a loading port for receiving a drug solution; a drug delivery lumen, wherein the drug delivery lumen has at least one release port and is configured to be implanted within an inner ear of a recipient; and an intermediate drug lumen, wherein the intermediate drug lumen extends from the implantable drug reservoir to the drug delivery lumen to form a fluid path between the loading port and the at least one release port; and wherein the implantable drug delivery device is configured to be primed with a drug prior to implantation in a recipient and the fluid path is electrically discontinuous in the absence of a conductive solution.

[0009] According to a fifth embodiment, an implantable medical device includes: a lead having at least one stimulation electrode positioned toward a distal end of the lead; an insulating fluid lumen having a closed proximal end and an open distal end; and a proximal electrode positioned within the insulating fluid lumen and toward the closed proximal end, wherein at least a distal section of the insulating fluid lumen is encapsulated within the lead. BRIEF DESCRIPTION OF DRAWINGS

[0010] Figure 1A A schematic diagram of an exemplary cochlear implant that can be configured to implement aspects of the technology presented herein is depicted in accordance with some example embodiments.

[0011] Figure 1B A functional block diagram of the cochlear implant of Figure 1A is depicted.

[0012] Figure 2 A diagram showing an example of an implantable drug delivery device in accordance with an embodiment.

[0013] Figure 3 A diagram showing an example of a syringe of an implantable drug delivery device in accordance with an embodiment positioned to be filled with a drug solution. Figure 2

[0014] Figures 4A-4C A diagram showing an example of an implantable drug delivery device of Figure 2 implanted within a cochlea of an inner ear of a recipient.

[0015] Figure 5A ​FIG. 1 is a diagram to illustrate an example of a drug delivery device attached to an implantable component of a cochlear implant.

[0016] Figure 5B FIG. 2 is a diagram to illustrate an example of a drug delivery device separate from an implantable component of a cochlear implant.

[0017] Figures 6A-6C FIG. 3 is a diagram to depict an example of a device that can be used to measure the electrical impedance or conductance of a drug solution within a drug delivery device prior to implanting the drug delivery device in a recipient to determine whether any obstructions are impeding the diffusion of the drug within the drug delivery device.

[0018] Figure 7 An example of a computing system within which one or more disclosed embodiments can be implemented is shown.

[0019] Figure 8 FIG. 4 is a diagram to depict an example of an implantable drug delivery device having a drug lumen integrated in a cochlear extra-cochlear lead of a cochlear implant. DETAILED DESCRIPTION

[0020] The technology presented herein is primarily described herein with reference to illustrative medical devices, including cochlear implant systems, merely for ease of description. However, it should be understood that the technology presented herein can also be used with a variety of other devices that provide a wide range of benefits to recipients, patients, or other users of the devices. As other examples, the technology presented herein can be used in or with medical devices such as other hearing prostheses, including bone conduction devices, hearing aids, middle ear auditory prostheses, direct acoustic stimulators, other electrically stimulating auditory prostheses (e.g., auditory brain stimulators), etc. The technology presented herein can also be used in or with medical devices that provide other types of sensory stimulation, such as vestibular devices (e.g., vestibular implants) and visual devices (i.e., bionic eyes). In at least some embodiments, the technology presented herein can be used in or with other forms of implantable devices such as implantable sensors, pacemakers, drug delivery systems, defibrillators, functional electrical stimulation devices, seizure devices (e.g., devices for monitoring and / or treating epileptic events), etc. The technology presented herein can also be applied in or with local drug delivery systems for treating pain, autoimmune diseases, and other innate and adaptive immune system related diseases.

[0021] The teachings detailed herein can be implemented in or with sensory prostheses such as hearing implants. Other types of sensory prostheses may include retinal implants. Therefore, unless otherwise stated, any teachings herein regarding sensory prostheses correspond to disclosures regarding the use of such teachings with / for hearing implants and with / for retinal implants, provided that it is possible in the art to do so. Furthermore, any teachings herein, unless otherwise indicated, correspond to disclosures regarding the use of such teachings with cochlear implants, bone conduction devices (active and passive transdermal bone conduction devices, and percutaneous bone conduction devices), and middle ear implants, provided that it is possible in the art to do so. It should be clear that any teachings herein regarding a particular sensory prosthesis correspond to disclosures regarding the use of such teachings with / for any of the aforementioned hearing prostheses, and vice versa. It is therefore inferred that at least some of the teachings detailed herein can be implemented in somatosensory implants and / or chemosensory implants. Therefore, any teachings in this document regarding sensory prostheses correspond to the disclosure of such teachings for use with / into somatosensory implants and / or chemosensory implants.

[0022] While the detailed teachings described herein are primarily concerned with hearing prostheses, it should be noted, consistent with the foregoing, that any disclosure herein regarding hearing prostheses corresponds to a disclosure of another embodiment utilizing the associated teachings with respect to any other device or prosthesis mentioned herein (whether a hearing prosthesis or a sensory prosthesis, such as a retinal prosthesis). In this respect, unless explicitly indicated and / or unless it is not possible to achieve this in the art, any disclosure herein regarding the induction of auditory perception corresponds to disclosures in other embodiments regarding the induction of other types of neural perception (e.g., visual / sight perception, tactile perception, olfactory perception, or gustatory perception). Any disclosure herein regarding devices, systems, and / or methods for or generating the final stimulation of the auditory nerve corresponds to disclosures regarding similar stimulation of the optic nerve utilizing similar components, methods, and / or systems.

[0023] Figure 1A This is a schematic diagram of an exemplary conventional cochlear implant (COCI) 100 configured to implement some aspects of the technology presented herein. Figure 1B yes Figure 1A A block diagram of a traditional cochlear implant 100. For ease of explanation, it will be described together. Figure 1A and 1B The cochlear implant 100 includes an external component 102 and an internal / implantable component 104. The external component 102 is attached directly or indirectly to the recipient's body and typically includes an external coil 106 and a magnet typically fixed relative to the external coil 106.Figures 1A-1B (Not shown in the image). External component 102 also includes one or more input elements / devices 113 for receiving input signals at sound processing unit 112. In this example, one or more input devices 113 include sound input devices 108 configured to capture / receive input signals (e.g., a microphone, pickup coil, etc., located by the receiver's auricle 110), one or more auxiliary input devices 109 (e.g., an audio port such as a direct audio input (DAI), a data port such as a universal serial bus (USB) port, a cable port, etc.), and a wireless transmitter / receiver (transceiver) 111, each located in, on, or near sound processing unit 112.

[0024] The sound processing unit 112 also includes, for example, at least one power supply 107, a radio frequency (RF) transceiver 121, and a processing module 125. The processing module 125 includes a plurality of elements, including an environment classifier 131, a sound processor 133, and an individualized self-speech detector 134. Each of the environment classifier 131, the sound processor 133, and the individualized self-speech detector 134 may be formed by one or more processors (e.g., one or more digital signal processors (DSPs), one or more processing cores, etc.) arranged to perform the operations described herein, firmware, software, etc. That is, the environment classifier 131, the sound processor 133, and the individualized self-speech detector 134 may each be implemented as a firmware element, partially or entirely using digital logic gates in one or more application-specific integrated circuits (ASICs), partially or entirely using software, etc.

[0025] exist Figure 1A and 1B In the example, the sound processing unit 112 is a behind-the-ear (BTE) sound processing unit, which is configured to be attached to and worn adjacent to the recipient's ear. However, it should be understood that the sound processing unit 112 may have other arrangements, such as an off-the-ear (OTE) processing unit (e.g., a component having a generally cylindrical shape and configured to be magnetically coupled to the recipient's head), a mini or micro BTE unit, an intracanal unit configured to be located in the recipient's ear canal, a body-worn sound processing unit, etc.

[0026] exist Figure 1A and 1BIn an exemplary embodiment, the implantable component 104 includes an implant body (main module) 114, a lead area 116, and an intracochlear stimulation assembly 118, all configured to be implanted under the skin / tissue (tissue) 105 of the recipient. The implant body 114 typically includes an hermetically sealed housing 115, in which an RF interface circuitry 124 and a stimulator unit 120 are disposed. The implant body 114 also includes an internal / implantable coil 122, which is typically outside the housing 115 but connected via an hermetically sealed feedthrough (…). Figure 1B (Not shown) is connected to the RF interface circuit system 124.

[0027] As described above, the stimulation component 118 is configured to be at least partially implanted in the cochlea 137 of a recipient. The stimulation component 118 includes a plurality of longitudinally spaced intracochlear electrical stimulation contacts (electrodes) 126, which together form a contact or electrode array 128 for delivering electrical stimulation (current) to the recipient's cochlea. The stimulation component 118 extends through an opening in the recipient's cochlea (e.g., cochlear fenestration, round window, etc.) and has a lead area 116 and an airtight feedthrough (…). Figure 1B (Not shown) is connected to the proximal end of the stimulator unit 120. The lead region 116 includes a plurality of conductors (wires) that electrically connect the electrode 126 to the stimulator unit 120.

[0028] As noted, the cochlear implant 100 includes an external coil 106 and an implantable coil 122. Coils 106 and 122 are typically wire antenna coils each comprising multiple turns of electrically insulated single-strand or multi-strand wire. Generally, a magnet is fixed in place relative to each of the external coil 106 and the implantable coil 122, but the magnet can be rotated or reoriented. In some embodiments, the external component 102 and / or the implantable component 104 may include magnet assemblies each having more than one magnet component. The magnets fixed relative to the external coil 106 and the implantable coil 122 facilitate operational alignment of the external coil and the implantable coil. This operational alignment of coils 106 and 122 enables the external component 102 to transmit data and, possibly, power to the implantable component 104 via a tightly coupled wireless link formed between the external coil 106 and the implantable coil 122. 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 external components to implantable components, and thus, Figure 1B Only one exemplary arrangement is shown.

[0029] As described above, the sound processing unit 112 includes a processing module 125. The processing module 125 is configured to convert an input audio signal into a stimulation control signal 136 for stimulating the recipient's first ear (i.e., the processing module 125 is configured to perform sound processing on the input audio signal received at the sound processing unit 112). In other words, the sound processor 133 (e.g., one or more processing elements implementing firmware, software, etc.) is configured to convert the captured input audio signal into a stimulation control signal 136 representing electrical stimulation to be delivered to the recipient. The input audio signal processed and converted into a stimulation control signal may be an audio signal received via the sound input device 108, a signal received via the auxiliary input device 109, and / or a signal received via the wireless transceiver 111.

[0030] exist Figure 1B In one embodiment, a stimulation control signal 136 is provided to an RF transceiver 121, which transceives the stimulation control signal 136 (e.g., in an encoded manner) transdermally to the implantable component 104 via an external coil 106 and an implantable coil 122. That is, the stimulation control signal 136 is received at the RF interface circuitry 124 via the implantable coil 122 and provided to the stimulator unit 120. The stimulator unit 120 is configured to use the stimulation control signal 136 to generate an electrical stimulation signal (e.g., a current signal) for delivery to the recipient's cochlea 137 via one or more stimulation contacts 126. In this way, the cochlear implant 100 electrically stimulates the recipient's auditory nerve cells to induce the recipient to perceive one or more components of the input audio signal, bypassing the missing or defective hair cells that typically translate acoustic vibrations into neural activity.

[0031] According to embodiments disclosed herein, a method is provided for obtaining a measurement representing the electrical impedance within a fluid channel of an implantable medical device (e.g., an implantable component 104 of a cochlear implant 100); and then processing the measurement to determine whether the implantable medical device has been infused for implantation in a recipient. According to another embodiment disclosed herein, a method is provided for measuring the electrical impedance of a drug solution contained in a fluid lumen of an implantable medical device. The fluid lumen extends between a loading port and at least one release port in the implantable medical device. The method further includes determining, based on the electrical impedance measurement, when the fluid lumen has been adequately infused with the drug solution. The implantable medical device may, for example, include a drug delivery device comprising a fluid channel or fluid lumen for delivering a drug to a recipient. The drug delivery device may be associated with another medical device (e.g., Figures 1A-1B It can be used together with a cochlear implant or another type of cochlear implant.

[0032] According to another embodiment disclosed herein, an implantable drug delivery device has an implantable drug reservoir having a loading port for receiving a drug solution. The implantable drug delivery device also has a drug delivery lumen having at least one release port and configured for implantation in the inner ear of a recipient. The implantable drug delivery device further has an intermediate drug lumen extending from the drug reservoir to the drug delivery lumen to form a fluid path between the loading port and the at least one release port. The implantable drug delivery device is configured to be infused with drug before implantation in a recipient, and the fluid path is electrically discontinuous in the absence of a conductive solution. The drug delivery device can be used with medical devices (e.g., Figures 1A-1B It can be used together with either a cochlear implant or another type of cochlear implant.

[0033] The term "drug" generally refers to a bioactive substance or combination of bioactive substances, including but not limited to pharmaceutical products, biological products, and other therapeutic substances and / or chemical compounds intended to provide therapeutic effects. These drugs may include, for example, anti-inflammatory drugs, anti-fibrotic drugs, anti-apoptotic drugs, drugs that inhibit or modify the body's immune response, and neurotrophic factors. Drug solutions may include steroids, BDNF, and antibiotics. The term "perfused" can refer to a device (including, for example, a reservoir or lumen of the device) being loaded, filled, and / or refilled with a liquid or solution. In at least some examples, the device is "perfused" when an uninterrupted fluid path extending between the inlet and outlet ports is present.

[0034] Figure 2 This is a diagram illustrating an example of a drug delivery device 200 according to an embodiment. The drug delivery device 200 is an implantable drug delivery device capable of delivering a drug to a recipient. A portion (or all) of the drug delivery device 200 may be implanted in the recipient to deliver the drug to an organ of the recipient (e.g., the inner ear).

[0035] Figure 2 The drug delivery device 200 shown includes a housing 201 (e.g., a titanium housing), a filter 204, a sleeve 205, and a drug release outlet 206. The housing 201 houses a diaphragm 202 (e.g., a self-healing silicone diaphragm) that covers a reservoir 203 within the housing 201. The housing 201 is designed to retain a drug solution within the reservoir 203 under the diaphragm 202. The filter 204 is coupled between the reservoir 203 and the sleeve 205. The sleeve 205 is a cylindrical tube encapsulating a lumen (i.e., a fluid lumen or fluid channel). The walls of the sleeve, or at least the sleeve forming the lumen, are electrically insulating. For example, the sleeve may be formed of or lined with biocompatible silicone. Figure 2The sleeve 205 shown has a different proximal section 205A and a distal section 205B. Figure 2 In the example, the diameter of the lumen in the proximal section 205A is larger than the diameter of the lumen in the distal section 205B. In an alternative embodiment, the sleeve 205 can be replaced with a sleeve having a constant diameter across the length of the sleeve or with a sleeve having a decreasing diameter across the length of the sleeve away from the housing 201.

[0036] Filter 204 allows the drug solution to be transferred from reservoir 203 to the lumen of cannula 205 while filtering out impurities such as bacteria. The lumens of the proximal section 205A and the distal section 205B of cannula 205 are connected together to allow the drug solution to be transferred between the lumens of the proximal section 205A and the distal section 205B. Drug release outlet 206 is attached to the distal end of cannula 205, such as... Figure 2 As shown in the diagram, outlet 206 includes a lumen that allows a drug solution to be delivered from cannula 205 through outlet 206. The lumen of outlet 206 has a release port located at the distal end of outlet 206. Outlet 206 is configured to be implanted in the inner ear or another organ of the recipient. In some embodiments, the housing 201 including reservoir 203 and cannula 205 may also be implanted in the recipient.

[0037] Figure 2 The embodiments of the drug delivery device 200 shown in the other figures herein are provided as illustrative examples and are not intended to be limiting. According to various examples, the drug may be delivered to the recipient at multiple points and / or continuously, along the cannula 205 and / or at the outlet 206. For example, in some embodiments, the drug delivery device may have multiple discrete release ports distributed along a segment of the cannula (e.g., the intracochlear segment of an inner ear drug delivery device). In other embodiments, the drug delivery device may have a single elongated release port extending along a segment of the cannula. In both embodiments, the drug outlet of the cannula is configured to deliver the drug to an anatomical structure adjacent to one or more release ports.

[0038] According to various embodiments, the drug release outlet 206 may include a filter having any shape, such as flat, elliptical, rectangular, cylindrical, etc. As an example not intended to be limiting, the drug release outlet 206 may include a bacterial column filter inside a polydimethylsiloxane (PDMS) tube made of porous titanium. As a more specific example not intended to be limiting, the dimensions of the drug release outlet 206 may be 0.15 x 0.5 millimeters (mm) (outer diameter x length), and for the filter, the maximum pore size is less than 0.2 micrometers. According to various embodiments, the sleeve 205 and the drug release outlet 206 may be made of any material. As an example not intended to be limiting, the sleeve 205 may be a tube made of PDMS. As another example not intended to be limiting, the sleeve 205 may be a tube made of titanium, wherein an electrically insulating biocompatible liner is applied to the inner wall defining the fluid lumen. According to yet another example not intended to be limiting, the filters in the filter 204 and the outlet 206 may each have a maximum pore size of 0.25 micrometers.

[0039] Figure 3 To illustrate the positioning of filling with a drug solution according to the embodiment Figure 2 A diagram showing an example of a syringe 301 in a drug delivery device 200. Figure 3 The syringe 301 includes a plunger 302, a reservoir 303, and a needle 304. The reservoir 303 is initially filled with a drug solution (e.g., a saline solution). The drug is dissolved in the drug solution. The plunger 302 is in contact with the drug solution in the reservoir 303.

[0040] The drug delivery device 200 is configured to be infused with a drug solution before implantation into a recipient. The drug delivery device 200 may be placed, for example, in a package (not shown) that facilitates the infusion of the drug delivery device 200 with the drug solution. Initially, the reservoir 203 is empty or filled with a sterile solution (e.g., purified water). To infuse the drug delivery device 200 with the drug solution, the user of the syringe 301 loads the drug solution into the housing 201 by first piercing the septum 202 of the drug delivery device 200 with the needle 304 and into the reservoir 203. The user can then press the plunger 302 to force the drug solution from the reservoir 303 through the needle 304 into the reservoir 203. The reservoir 203 has an opening into which a portion of the filter 204 is inserted. This opening in the reservoir 203 serves as a loading port for receiving the drug solution and providing the drug solution to the filter 204. In other embodiments, plunger 302 may be replaced by a pump, syringe driver, or another mechanism for forcing drug solution from reservoir 303 through needle 304 into reservoir 203.

[0041] The user can continue to press the plunger 302 to force the drug solution from the reservoir 203 through the filter 204, through the lumen of the sleeve 205, and through the lumen of the outlet 206, until the drug solution forms droplets 307 at the release port of the lumen of the outlet 206. Figure 3 As shown, drug 305 is dissolved in the drug solution within the lumen of reservoir 203, cannula 205, and droplet 307. After the drug delivery device 200 has been successfully infused with the drug solution, it can then be implanted into the recipient. The outlet 206 can be implanted, for example, into the recipient's target organ (e.g., the cochlea). When the outlet 206 is implanted into the recipient's target organ, the release port of the lumen of the outlet 206 can release drug 305 into the target organ.

[0042] Figures 4A-4C To show Figure 2 Figures show various examples of drug delivery devices 200 after being filled with a drug solution. Figures 4A-4C In the middle, the drug release outlet 206 has been implanted in the cochlea 137 of the recipient's inner ear 400. Figure 4A In the example, the drug delivery device 200 has already been described above regarding Figure 3 After being infused with a drug solution, the drug delivery device 200's drug release outlet 206 is implanted into the recipient's cochlea 137. Figure 4A In the example, drug 305 diffuses from drug delivery device 200 into the fluid within the recipient's cochlea 137 in a drug solution, rather than being pumped into the recipient, in order to avoid increased pressure within the cochlea 137. Figure 4A The drug 305 in the drug solution is depicted diffusing from the drug delivery device 200 into the recipient's cochlea 137. The drug 305 diffuses from the drug solution in the reservoir 203 through the drug solution in the filter 204, through the drug solution in the lumen of the cannula 205, and through the drug solution in the lumen of the outlet 206 into the fluid within the recipient's cochlea 137.

[0043] Following instillation, a drug concentration gradient exists between the reservoir 203 and the cochlea 137, causing drug molecules of drug 305 to move from a higher drug concentration in the reservoir 203 towards a lower drug concentration in the cochlea. The concentration of drug 305 decreases as drug 305 diffuses through the filter 204, cannula 205, and outlet 206 into the fluid within the cochlea 137. As long as the drug does not accumulate in the cochlea, the concentration of drug 305 in the cochlea 137 remains relatively low. Alternatively, drug 305 diffuses into the rest of the recipient's body and is eventually metabolized or removed from the body. Therefore, the concentration of drug 305 in the cochlea 137 remains lower than the concentration of drug 305 in each of the reservoir 203, cannula 205, and outlet 206 (as per [previous treatment]).Figure 4A (As shown in Figure 402), until all drug molecules of drug 305 have left device 200 and equilibrium is achieved.

[0044] The drug solution in a drug delivery device (such as drug delivery device 200) may include entrained gas, which may or may not impede the diffusion of the drug in the drug solution. As an example, entrained gas can reduce the volume of a reservoir 203 that can be used to store the drug solution. If entrained gas reduces the volume of the reservoir 203 that can be used to store the drug solution, the concentration of the drug in the reservoir 203 decreases more rapidly, and the release rate of the drug at the outlet 206 is lower than expected, but the diffusion of drug molecules from the reservoir to the outlet 206 is not impeded.

[0045] In some cases, one or more large air bubbles may become trapped within the drug delivery device, potentially blocking or hindering the diffusion of the drug solution to the recipient. For example, an air bubble may become trapped in a lumen of the cannula 205 of the drug delivery device 200. An air bubble in a lumen of the cannula 205 may potentially block or limit the diffusion of drug 305 from the reservoir 203 into the cochlea 137, preventing the complete delivery of drug 305 to the recipient.

[0046] Figure 4B An example is depicted where an air bubble 410 is trapped within the lumen of the proximal segment 205A of the cannula 205. The air bubble 410 completely blocks the lumen of the proximal segment 205A, preventing the drug 305 from being delivered to the recipient's cochlea 137. Figure 4C An example is depicted where an air bubble 411 is trapped within the reservoir 203 at the loading port leading to the filter 204. The air bubble 411 completely blocks the loading port of the reservoir 203. The air bubble 411 can separate the cannula 205 from the reservoir 203, which slows the release of the drug 305 and eventually stops the delivery of the drug 305 to the cochlea 137 after the cannula 205 has exhausted the drug molecules.

[0047] In some exemplary embodiments, the implantable drug delivery device (e.g., drug delivery device 200) may be used in conjunction with an implantable medical device (e.g., a cochlear implant). The implantable drug delivery device may be integrated with the implantable medical device, or alternatively, may be separate from the implantable medical device. Figure 5A This figure illustrates an example of a drug delivery device 500 attached to an implantable component 501 of a cochlear implant. The drug delivery device 500 includes one or more cannulas 502 connected to a port of the implantable component 501. The drug delivery device 500 can be used to deliver drugs to a recipient via the cannulas 502 and the implantable component 501.

[0048] Figure 5B This figure illustrates an example of a drug delivery device 510 detachable from the implantable component 511 of the cochlear implant. Figure 5B In the example, the drug delivery device 510 can deliver the drug directly to the recipient's cochlea, as described above. Figures 4A-4C As described. The drug delivery device 510 can be, for example... Figure 2 Drug delivery device 200.

[0049] Before implanting a drug delivery device (e.g., drug delivery devices 200, 500, and 510) into a recipient, it is generally desirable to determine whether air bubbles (or other obstructions) are hindering drug diffusion within the drug delivery device. Figures 6A-6C The diagram illustrates an example of a measuring device that can be used to measure the impedance or conductivity of a drug solution within a drug delivery device before implantation into a recipient to determine if any obstructions are hindering drug diffusion within the device. The measured impedance or conductivity of the drug solution can be processed (e.g., by a computing system) to determine whether the drug delivery device is infused for implantation into the recipient. As an example... Figures 6A-6C The measuring device is shown as measuring in Figure 2 The electrical impedance or conductivity of the drug solution within the drug delivery device 200. In this document, the term conductivity refers to the reciprocal of electrical impedance. Therefore, a measurement of conductivity also represents electrical impedance.

[0050] Figure 6A The diagram illustrates an example of a measuring device 606, configured to measure the impedance or conductivity of a drug solution in a drug delivery device 200 using two electrodes 603-604. Figure 6A In the example, measuring device 606 is electrically connected to two conductors 601 and 602. Conductor 601 is electrically connected to a first electrode 603, and conductor 602 is electrically connected to a second electrode 604. Electrode 603 is electrically connected to a first terminal of measuring device 606 via conductor 601. Electrode 604 is electrically connected to a second terminal of measuring device 606 via conductor 602. Conductors 601-602 may be, for example, a common lead connecting electrodes 603-604 to appropriate terminals of measuring device 606.

[0051] To measure the impedance or conductivity of the drug solution in the drug delivery device 200, electrode 603 is brought into electrical contact with the drug solution to be tested in the reservoir 203 (by piercing the diaphragm 202), and electrode 604 is brought into electrical contact with the drug solution to be tested in the droplet 307 at the distal end of the drug release outlet 206. Therefore, Figure 6A A measuring device 606 is shown, which is connected to measure the impedance or conductivity of a drug solution in a drug delivery device 200 between a reservoir 203 and a droplet 307.

[0052] Measuring device 606 can use any impedance or conductance measurement technique to measure the impedance and / or conductance of the drug solution in the drug delivery device 200 between electrodes 603 and 604. As an example, measuring device 606 can apply a known voltage V to electrodes 603-604 via conductors 601-602, measure the direct current I generated in conductors 601-602, and then calculate the resistance R in the drug solution in the drug delivery device 200 according to Ohm's law (i.e., R = V / I). Another example is to apply a known current I, measure the voltage V between electrodes 603-604, and then calculate the resistance R in the drug solution in the drug delivery device 200 according to Ohm's law (i.e., R = V / I).

[0053] As another example, the measuring device 606 can use electrodes 603-604 to calculate the complex electrical impedance Z of the drug solution passing through the drug delivery device 200 within a frequency range using electrical impedance spectroscopy (EIS). For electrical impedance spectroscopy, the measuring device 606 can apply a known sinusoidal voltage signal V of a known frequency f to electrodes 603-604 through conductors 601-602, and measure the phase shift phi between the resulting sinusoidal current signal I and the voltage signal V and current signal I in conductors 601-602. To determine the complex impedance Z of the circuit consisting of conductors 601-602, electrodes 603-604, and the drug solution in the drug delivery device 200. The resistance R, the total complex impedance Z, or its components (including the phase shift phi) are calculated. In these examples, resistance R (real number) or reactance X (imaginary number) is used to determine the impedance of the drug solution in the drug delivery device 200. As used herein, the measurement of impedance also includes the calculation of impedance based on one or more measurements (e.g., voltage, current, and / or phase shift); the measurement of conductance; the calculation of conductance based on one or more measurements (e.g., voltage, phase shift, and / or current); and any component of impedance or conductance (including phase shift phi). Measurements of resistance (R) or reactance (X); and any component of the measured reactance or conductance (including phase shift phi). Calculation of resistance R or reactance X.

[0054] The phase shift phi of the complex impedance at a specific frequency This allows for the calculation of both the capacitive and resistive portions of the total impedance Z. For example, the capacitive portion of the total impedance can be increased if air is present in the drug delivery device. If the drug delivery device is completely filled with a drug solution, the capacitive portion of the total impedance is limited to the metal-liquid interface of the drug delivery device, which is typically a known value. Fluid-filled lumens (e.g., the lumen of sleeve 205) typically only increase the resistive impedance. Air bubbles may add a new capacitive portion to the total impedance, which can indicate the presence of air in the drug delivery device.

[0055] Alternatively, the reciprocal of the resistance R, the reciprocal of the total complex impedance Z, or the components of the complex impedance Z (including the phase shift phi) can be calculated. The reciprocal of the resistance (R) or reactance (X) can be used as a measure of the conductance of the drug solution in the drug delivery device 200. As another example, the measuring device 606 can measure any one or more of the resistance, capacitance, and / or inductance between electrodes 603-604 at any frequency or within any frequency range of the current or voltage signal applied to electrodes 603-604 to generate a measure of the impedance or conductance of the drug solution.

[0056] As an example, the measuring device 606 may be a stand-alone instrument, a device integrated (or used together) with a computer or computing system that generates the user interface 605, or part of a medical device. As a more specific example, the measuring device 606 may be integrated with implantable components (e.g., Figure 5A It is part of a cochlear implant system used together with implantable component 501.

[0057] In some embodiments, the cochlear implant may perform at least some of the functions of the measuring device 606. The measuring device 606 may be, for example... Figures 1A-1BThis is a portion of the implant body 114 of the cochlear implant 100. Electronics within the hermetically sealed housing 115 of the cochlear implant 100 can measure the impedance between electrodes 603-604. In some embodiments, the cochlear implant has dedicated measuring electrodes 603-604 integrated with the implantable component 104. For example, a drug reservoir housing 201 and / or outlet 206 may be configured to serve as measuring electrodes 603-604. In at least some embodiments, the reservoir 201 and / or outlet 206 are made of a conductive material (e.g., a biocompatible metal) and / or include conductive sections exposed to fluid paths within the drug delivery device (e.g., one or more intentionally exposed conductive inner surfaces within the reservoir and / or outlet). In other embodiments, existing cochlear implant electrodes (e.g., intracochlear electrode 126 and / or extracochlear electrode) may be electrically coupled to measuring electrodes 603-604 that are not part of the implantable component 104. For example, the sterile package containing the implantable component 104 can be configured to electrically bridge one or more intracochlear electrodes 126 and / or extracochlear electrodes to the loading and / or release ports of the drug delivery device during pre-implantation infusion, allowing the cochlear implant system to measure impedance within the fluid path and confirm that the implantable component 104 is ready for implantation. In some embodiments, the sterile package can be configured to connect the extracochlear bulb electrode (connected to...) Figure 1A The flywire of the cochlear implant 100 shown is held close to the drug outlet, such that the ball electrode is in direct contact with the droplet 307 formed at the outlet 206. In other embodiments, an indirect electrical bridge (e.g., an electrical conductor embedded in the packaging) is used to connect the intracochlear electrode 126 and / or the extracochlear electrode to the loading port and / or release port. Electrical connection to the fluid in the reservoir 203 can be made by connecting to the reservoir housing 201, directly or indirectly via a conductive fluid bridge to the needle 304, or to a solid conductor connected to the packaging of the cochlear implant. For example, by shaping the aseptic packaging of the cochlear implant such that the outlet 206 and the electrode 604 are in the same well within the packaging, the electrode 604 can be made to contact the droplet 307. Similarly, in this example, the electrical connection between the electrode 603 and the drug solution can be created using a conductive patch, for example, having a conductive wire clipped to the needle of an infusion syringe (e.g., syringe 301).

[0058] Alternatively, one or both of electrodes 603-604 may be electrical probes. As other examples, the measuring device 606 may use the housing 201 (e.g., which may be made of metal or other conductive material), the liner or wall of the reservoir 203 filled with the drug solution, or the filter 204 as electrodes for measuring the impedance or conductivity in the drug solution, instead of electrode 603. In these examples, conductor 601 may be in electrical contact with housing 201, reservoir 203, or filter 204. In some embodiments, electrode 604 may be integrated, for example, into the packaging housing the drug delivery device 200 to facilitate connection with conductor 602 and droplet 307.

[0059] The measuring device 606 can be used to measure the impedance or conductivity of the drug solution within the drug delivery device 200 to determine whether any obstruction is preventing or hindering the diffusion of the drug 305 within the drug delivery device 200 during infusion. The measuring device 606 can measure the impedance and / or conductivity of the drug solution in the drug delivery device 200, for example, continuously or at intervals (e.g., every 10 milliseconds), to identify the presence of any obstruction in the drug solution.

[0060] Measuring device 606 can transmit one or more measurements of the impedance or conductance of the drug solution in drug delivery device 200 (e.g., using a phase shift between current and voltage) to a computing system. The computing system can, for example, determine the likelihood that entrained gas will impede or prevent the diffusion of drug 305 within drug delivery device 200 based on the impedance or conductance measurements received from measuring device 606. The impedance or conductance of the drug solution can fluctuate as the drug delivery device is perfused with the drug solution. The computing system may include software that monitors the stability of the impedance or conductance measurements obtained from the drug solution before determining whether the impedance or conductance indicates that the drug delivery device has been successfully perfused. This software can, for example, detect a relative decrease in impedance as an indication of successful perfusion, instead of comparing the impedance to a predefined threshold (i.e., this might increase the need to calibrate measuring device 606).

[0061] As a supplement or alternative to measuring the impedance or conductivity of the drug solution in the drug delivery device 200 caused by bubbles affecting drug diffusion, the measuring device 606 may also, or alternatively, measure the impedance or conductivity of the drug solution in the drug delivery device 200 caused by residual gas trapped elsewhere in the drug delivery device 200. Bubbles can move within the drug delivery device, becoming residual air, which may potentially hinder drug diffusion at a later time.

[0062] The computing system can use user interface 605 to provide the user with measurements of the impedance or conductivity of the drug solution in the drug delivery device 200. User interface 605 can be generated, for example, by software running on a computing system that receives the measurements of the impedance or conductivity of the drug solution from measuring device 606. User interface 605 can provide the user with the measurements of the impedance or conductivity of the drug solution, for example, visually via a display screen or via audio through a speaker.

[0063] As another example, the user interface 605 may include a light-emitting diode (LED) that turns red in response to a measured impedance of the drug solution in the drug delivery device 200 being at or above a predefined threshold indicating that the drug delivery device 200 has not yet been successfully infused. In this example, the LED changes from red to green in response to a measured impedance of the drug solution in the drug delivery device 200 being less than (or equal to) a predefined threshold (e.g., in the range of 100 ohms to 100 kiloohms) indicating that the drug delivery device has been successfully infused (e.g., fully filled) without large air bubbles. The infused drug delivery device 200 is then ready for implantation and for delivering drug 305 to the recipient.

[0064] Figures 6B-6C The diagram illustrates an example configuration of a measuring device 606, which is coupled to measure the impedance or conductivity of a drug solution in a drug delivery device 200 using electrodes 604 and a syringe 301. Figures 6B-6C In the example, conductor 601 is electrically connected to the needle 304 of syringe 301, and conductor 602 is electrically connected to electrode 604. The needle 304 is electrically connected to a first terminal of measuring device 606 via conductor 601, and electrode 604 is electrically connected to a second terminal of measuring device 606 via conductor 602.

[0065] exist Figures 6B-6C In the example, the needle 304 used to infuse the drug delivery device 200 with the drug solution is also used by the measuring device 606 as an electrode (i.e., replacing electrode 603) to measure the impedance or conductivity of the drug solution. (See above regarding...) Figure 3 As discussed, the needle 304 is brought into contact with the drug solution in the reservoir 203 by piercing the diaphragm 202. The electrode 604 may be, for example, a common impedance probe, which, during infusion, is brought into contact with droplets 307 of the drug solution formed at the outlet 206 of the drug delivery device 200, as in the previous example.

[0066] exist Figures 6B-6C In the example, measuring device 606 can use any impedance or conductance measurement technique, including those mentioned above. Figure 6AThe described impedance and conductivity measurement techniques measure the resistance or conductivity of a drug solution in a drug delivery device 200 between needle 304 and electrode 604. Measuring device 606 can measure the resistance or conductivity of the drug solution in the drug delivery device 200 to determine if any obstruction is hindering the diffusion of drug 305 within the drug delivery device 200, as described above. Figure 6A For example, the measuring device 606 can generate a measured or calculated value of impedance or conductance, which indicates the presence of a drug solution (e.g., in the lumen of the proximal segment 205A of the sleeve 205) in the drug solution. Figure 6C (as shown in the diagram) or in any other part of the drug delivery device 200, such as bubble 620.

[0067] Measuring device 606 can measure the impedance and / or conductivity of the drug solution in drug delivery device 200 continuously or at intervals (e.g., every 10 milliseconds), for example, during the infusion of the drug solution with syringe 301. Initially, during infusion, the impedance of the drug solution between needle 304 and electrode 604 is high (e.g., in the megaohm range) until droplet 307 forms and wets electrode 604, causing a rapid decrease in impedance. If there are no air bubbles in the drug solution between needle 304 and electrode 604, the impedance of the drug solution can depend on the conductivity of the drug solution, the distance between needle 304 and electrode 604, the cross-sectional area of ​​the volume of drug solution between needle 304 and electrode 604, the surface area and material of needle 304 and electrode 604, and the temperature of the drug solution (by way of example), ranging from 100 ohms to 100 kiloohms. Measuring device 606 can be calibrated, for example, before use to compensate for these factors. Measuring device 606 can provide the measured values ​​of the impedance or conductivity of the drug solution in drug delivery device 200 to the computing system for comparison with one or more predefined thresholds and / or for display to the user using user interface 605, as described above. Figure 6A The discussion.

[0068] According to other embodiments, a measuring device (e.g., measuring device 606) can be used to measure the impedance or conductivity of the drug solution in the drug delivery device while it is being refilled with a drug solution (e.g., refilled into the reservoir 203 of device 200) to determine whether any obstructions (e.g., air bubbles) are present in the drug solution. As an example, if the drug delivery device 200 is implanted under the skin of a recipient, the device 200 can be refilled with a drug solution by inserting two needles through the recipient's skin into the reservoir 203 of the device 200. One of the needles acts as an inlet for introducing new drug solution into the drug delivery device, and the other needle acts as an outlet for solution removed from the drug delivery device. The inlet needle is coupled to a first terminal of measuring device 606, and the outlet needle is coupled to a second terminal of measuring device 606. The measuring device 606 can then measure the impedance or conductivity within the reservoir during refilling to monitor the introduction of gas, detect the presence of any bubbles formed in the reservoir 203 due to the refilling process, and / or confirm when the reservoir 203 is fully filled with the new drug solution.

[0069] According to another embodiment, the measuring device 606 is also used to measure the impedance or conductivity of the drug solution in the drug delivery device to determine whether any obstruction exists in the drug lumen when the drug delivery device is being refilled with drug solution using an inlet needle and a conductive patch. In this embodiment, the inlet needle is coupled to a first terminal of the measuring device 606, and the conductive patch (e.g., an electrode patch) is placed on the recipient's skin and coupled to a second terminal of the measuring device 606. Similarly, in this embodiment, the inlet needle may be electrically isolated from the recipient's skin / tissue pierced by the inlet needle. To electrically isolate the inlet needle, the shaft of the inlet needle is coated with an electrically insulating material (e.g., parylene, silicone, silicon carbide, etc.), and only the outlet of the inlet needle, which contacts the drug solution inside the reservoir of the drug delivery device, is bare metal for electrical connection with the drug solution. This configuration avoids a low-impedance parallel current path through the recipient's tissue to the return electrode (e.g., the conductive patch on the skin). Current is forced through the drug delivery device, exits through the outlet of the drug delivery device, and returns to the conductive patch. The circuit is closed via the inlet needle, the drug solution inside the electrically insulated lumen of the drug delivery device, the recipient's body fluids / tissue, the recipient's skin, a conductive patch on the skin, and a cable connecting the conductive patch and the second terminal of the measuring device 606. Alternatively, instead of the skin patch electrode, the second needle can pierce the recipient's skin to bring it into contact with the recipient's body fluids for measuring the impedance or conductivity of the drug solution in the drug delivery device. These configurations allow for testing for air bubbles in the fluid path of the drug delivery device by measuring the impedance or conductivity of the drug solution within the device.

[0070] As another example, the measuring device 606 can be integrated with an implantable component of a cochlear implant to enable impedance testing to be performed while the device is being refilled in vivo. Electronics within the hermetically sealed housing 115 of the implantable component 104 can be configured to measure the impedance between a reservoir electrode (e.g., a conductive inner surface of the reservoir housing 201) and a drug outlet electrode (e.g., a conductive surface at the release port of the drug lumen). In some embodiments, a conductive biocompatible bacterial filter is used at the outlet of the drug delivery device (i.e., the distal end of the fluid lumen). In these embodiments, the bacterial filter can be electrically connected to the measuring device 606 and configured to act as the outlet electrode. Similarly, the reservoir housing can be configured to act as a reservoir electrode.

[0071] Figure 7 An example of a computing system 700 is shown, within which one or more of the disclosed embodiments may be implemented. For example, the computing system 700 may generate or include... Figures 6A-6C User interface 605. Computing systems, environments, or configurations suitable for use with the examples described herein include, but are not limited to, personal computers, server computers, handheld devices, laptop devices, multiprocessor systems, microprocessor-based systems, programmable consumer electronics (e.g., smartphones), network computers, minicomputers, mainframe computers, tablet computers, distributed computing environments including any of the aforementioned systems or devices, etc. Computing system 700 may be a single virtual or physical device operating in a networked environment via a communication link to one or more remote devices. The remote device may be an auditory prosthesis (e.g., an auditory phallus). Figures 1A-1B (cochlear implants), personal computers, servers, routers, network personal computers, peer-to-peer devices or other public network nodes.

[0072] The computing system 700 includes at least one processing unit 702 and a memory 704. The processing unit 702 includes one or more hardware or software processors (e.g., a central processing unit) that can receive and execute instructions. The processing unit 702 can communicate with and control the execution of other components of the computing system 700. The memory 704 is one or more software-based or hardware-based computer-readable storage media operable to store information accessible by the processing unit 702.

[0073] In addition to storing other data, memory 704 may store instructions that can be executed by processing unit 702 to implement an application or to enable the operations described herein. Memory 704 may be volatile memory (e.g., random access memory or RAM), non-volatile memory (e.g., read-only memory or ROM), or a combination thereof. Memory 704 may include temporary or non-temporary memory. Memory 704 may also include one or more removable or non-removable storage devices. In examples, memory 704 may include non-temporary computer-readable storage media, such as RAM, ROM, EEPROM (electrically erasable programmable read-only memory), flash memory, optical disc storage devices, magnetic storage devices, solid-state storage devices, or any other memory medium that can be used to store information for later access. In examples, memory 704 encompasses modulated data signals (e.g., signals whose one or more characteristics are set or changed in a manner that encodes information in the signal), such as carrier waves or other transmission mechanisms, and includes any information delivery medium. By way of example and not limitation, memory 704 may include wired media (e.g., a wired network or direct wired connection), and wireless media (e.g., acoustic, radio frequency, infrared and other wireless media) or combinations thereof.

[0074] In the illustrated example, system 700 also includes a network adapter 706, one or more input devices 708, and one or more output devices 710. System 700 may include other components such as a system bus, component interfaces, a graphics system, a power supply (e.g., a battery), and other components.

[0075] Network adapter 706 is a component of computing system 700 that provides network access to network 712. Network adapter 706 can provide wired or wireless network access and can support one or more of various communication technologies and protocols, such as Ethernet, cellular, Bluetooth, near field communication, and RF (radio frequency), etc. Network adapter 706 may include one or more antennas and associated components configured to communicate wirelessly according to one or more wireless communication technologies and protocols.

[0076] One or more input devices 708 are means by which the computing system 700 receives input from a user. One or more input devices 708 may include physically actuated user interface elements (e.g., buttons, switches, or dial pads), touchscreens, keyboards, mice, pens, and voice input devices, as well as other input devices.

[0077] One or more output devices 710 are means through which the computing system 700 can provide output to a user. Output devices 710 may include displays, speakers, and printers, as well as other output devices, and may be part of or used with the user interface 605.

[0078] Figure 8 The diagram illustrates an example of a drug delivery device 800, which has a drug delivery lumen 801 integrated into the external cochlear cannula of a cochlear implant. Figure 8 In the example, the drug delivery lumen 801 of the drug delivery device 800 is integrated in Figures 1A-1B The cochlear implant 100 includes an external cochlear lead 116. The drug delivery device 800 also includes a drug delivery lumen 802 integrated into the cochlear intraelectrode array 128 of the cochlear implant 100. The drug delivery device 800 is configured to deliver a drug solution to the recipient's cochlea via the drug delivery lumen 801-802. The drug delivery device 800 may, for example, have a... Figure 2 The drug delivery device 200 has the same or similar structure.

[0079] Unless otherwise expressly indicated, any embodiment or feature disclosed herein may be combined with any one or more other embodiments and / or other features disclosed herein. The use of any embodiment or feature disclosed herein in conjunction with any one or more other embodiments and / or other features disclosed herein is expressly excluded unless otherwise expressly indicated. It should be noted that any method detailed herein also corresponds to the disclosure of one or more or all of the method actions of an apparatus and / or system configured to perform those associated with the apparatus and / or system detailed herein. It should also be noted that any disclosure of an apparatus and / or system detailed herein corresponds to methods of making and / or using the apparatus and / or system, including methods of using the apparatus according to the functions detailed herein.

[0080] The foregoing description of exemplary embodiments of the invention has been presented for illustrative purposes. The foregoing description is not intended to be exhaustive or to limit the invention to the examples disclosed herein. In some cases, features of the invention may be used without corresponding use of other features set forth. Many modifications, substitutions, and variations are possible in accordance with the foregoing teachings without departing from the scope of the invention.

Claims

1. A method comprising: Obtain a measurement value representing the electrical impedance within the fluid channel of an implantable medical device; as well as The measured values ​​are processed to determine whether the implantable medical device has been infused for implantation in a recipient.

2. The method of claim 1, wherein the implantable medical device is configured to deliver a therapeutic substance to the recipient, and the method further comprises processing the measurement to determine that a solution containing the therapeutic substance fills the fluid channel.

3. The method of claim 1, wherein the implantable medical device is configured to deliver a therapeutic substance to the recipient, and the method further comprises processing the measurement to determine that the solution containing the therapeutic substance extends continuously along the length of the fluid channel extending from the loading port to the release port.

4. The method according to any one of claims 1-3, further comprising: While the implantable medical device is being filled with a solution containing a therapeutic substance, a series of measurements representing the electrical impedance in the fluid channels of the implantable medical device are obtained over a period of time, and The implantable medical device is determined to be ready for implantation based on the series of measurements.

5. The method according to any one of claims 1-4, further comprising measuring the impedance along the length of the fluid channel extending from the proximal loading port to the distal release port.

6. The method according to any one of claims 1-5, further comprising: Execution instructions, the instructions causing the implantable medical device to obtain the measurement value using two or more implantable electrodes of the implantable medical device, and The measured values ​​are transmitted to an external device for processing.

7. The method according to any one of claims 1-6, wherein obtaining the measurement value representing the impedance further comprises using the needle of a syringe as an electrode to obtain the measurement value representing the impedance within the fluid channel.

8. The method according to any one of claims 1-7, wherein obtaining the measured value representing the impedance further comprises obtaining the measured value representing the impedance between a reservoir of solution in the implantable medical device within the fluid channel and a droplet at a release outlet of the implantable medical device.

9. The method of any one of claims 1-8, wherein the method further comprises, while refilling the fluid channel with the solution, obtaining an additional measurement of the electrical impedance within the fluid channel representing the implantable medical device, and processing the additional measurement to determine whether the fluid channel is perfused with the solution.

10. A method comprising: Measuring the electrical impedance of a drug solution contained in a fluid lumen within an implantable medical device, wherein the fluid lumen extends between a loading port and at least one release port within the implantable medical device, and The timing of the drug solution being injected into the fluid lumen is determined based on the electrical impedance.

11. The method of claim 10, wherein measuring the impedance further comprises measuring the impedance using at least two implantable electrodes of the implantable medical device.

12. The method according to any one of claims 10-11, wherein measuring the impedance further comprises measuring the impedance of the drug solution through at least one sleeve including the fluid lumen.

13. The method according to any one of claims 10-12, wherein measuring the impedance further comprises measuring the impedance during refilling of the fluid lumen with the drug solution.

14. The method according to any one of claims 10-13, wherein measuring the impedance further comprises calculating the impedance using measurements obtained from the implantable medical device.

15. A non-transitory computer-readable storage medium, the non-transitory computer-readable storage medium comprising computer-readable instructions stored thereon, the computer-readable instructions being configured to cause a computing system to: The electrical impedance of the drug solution in the medical device is determined based on measurements obtained from the medical device; and The electrical impedance of the drug solution is used to determine whether there is an obstacle preventing the diffusion of therapeutic substances within the drug solution in the medical device.

16. The non-transitory computer-readable storage medium of claim 15, wherein the computer-readable instructions further cause the computing system to determine, based on the electrical impedance of the drug solution, whether the medical device is infused for implantation in a recipient.

17. The non-transitory computer-readable storage medium according to any one of claims 15-16, wherein the computer-readable instructions further cause the computing system to provide a user with a representation of the impedance of the drug solution using a user interface.

18. The non-transitory computer-readable storage medium according to any one of claims 15-17, wherein the computer-readable instructions further cause the computing system to determine the electrical impedance of the drug solution in the medical device using electrical impedance spectroscopy.

19. The non-transitory computer-readable storage medium according to any one of claims 15-18, wherein the computer-readable instructions further cause the computing system to determine the impedance of the drug solution during the refilling of the drug solution into the lumen of the medical device.

20. An implantable drug delivery device, comprising: An implantable drug reservoir, wherein the implantable drug reservoir has a loading port for receiving a drug solution; A drug delivery lumen, wherein the drug delivery lumen has at least one release port and is configured to be implanted in the inner ear of a recipient; as well as An intermediate drug lumen, wherein the intermediate drug lumen extends from the implantable drug reservoir to the drug delivery lumen to form a fluid path between the loading port and the at least one release port, and The implantable drug delivery device is configured to be infused with a drug before being implanted into a recipient, and the fluid path is electrically discontinuous in the absence of a conductive solution.

21. The implantable drug delivery device of claim 20, wherein the drug delivery lumen has an average inner diameter smaller than the average inner diameter of the intermediate drug lumen.

22. The implantable drug delivery device according to any one of claims 20-21, wherein the intermediate drug lumen is integrated in the cochlear external lead of the cochlear implant, and wherein the drug delivery lumen is integrated in the cochlear intraelectrode array of the cochlear implant.

23. The implantable drug delivery device according to any one of claims 20-22, wherein the implantable drug delivery device includes at least one filter within the fluid path, and wherein the at least one filter has a maximum pore size of 0.25 micrometers.

24. The implantable drug delivery device according to any one of claims 20-22, wherein the at least one release port of the drug delivery lumen comprises a filter having a maximum pore size of 0.25 micrometers.

25. The implantable drug delivery device according to any one of claims 20-24, wherein the loading port of the implantable drug reservoir includes a self-healing diaphragm.

26. The implantable drug delivery device according to any one of claims 20-25, wherein the implantable drug delivery device comprises at least two electrodes, and wherein the implantable drug delivery device is configured to use the at least two electrodes to measure the impedance across the fluid path between the loading port and the at least one release port.

27. An implantable medical device, the implantable medical device comprising: A lead wire having at least one stimulating electrode positioned toward the distal end of the lead wire; An insulating fluid lumen having a closed proximal end and an open distal end; And a proximal electrode, which is located within the insulating fluid lumen and toward the closed proximal end, wherein at least a distal segment of the insulating fluid lumen is enclosed within the lead.

28. The implantable medical device of claim 27, wherein the proximal closed end of the insulating fluid lumen is closed by a diaphragm.

29. The implantable medical device of claim 27, wherein the proximal closed end of the insulated fluid lumen comprises a drug reservoir.

30. The implantable medical device of claim 27, wherein the implantable medical device further comprises a distal electrode disposed in the distal segment of the insulating fluid lumen toward the open distal end.

31. The implantable medical device of claim 30, wherein the implantable medical device further comprises an electronic circuitry system configured to measure the impedance between the proximal electrode and the distal electrode.

32. The implantable medical device of claim 30, wherein the distal electrode is part of a bacterial filter, and the bacterial filter is disposed at the open distal end of the insulating fluid lumen.

33. The implantable medical device of claim 27, wherein the open distal end of the insulating fluid lumen is positioned adjacent to the distal end of the lead.

34. The implantable medical device of claim 27, wherein the open distal end of the insulating fluid lumen is positioned distal to the distal end of the lead.

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