Electric circuit arrangement for a biomedical interface

Abstract

The invention relates to an electric circuit arrangement for a biomedical interface, having electric contacts of which a number n of electric contacts are used for contacting at least one implantable electrode arrangement which can be attached to an organic structure, and having at least one electric function block which is electrically connected to at least one of the n electric contacts. The invention is characterised in that the at least one electric function block has function elements implemented by means of SOI technology, and that the at least one electric function block can be operated at a supply voltage to which an electric average potential can be assigned, which supply voltage corresponds to an electric potential which can be assigned to the organic structure.

Description

[0001] Electrical circuit arrangement for a biomedical interface

[0002] Technical area

[0003] The invention relates to an electrical circuit arrangement for a biomedical interface, comprising electrical contacts, of which a number n of electrical contacts serves to contact at least one implantable electrode arrangement attachable to an organic structure, and comprising at least one electrical functional block which is electrically connected to at least one of the n electrical contacts.

[0004] State of the art

[0005] Functional electrical stimulation or neural stimulation (FES / FNS) is a technique for treating various types of neurological disorders by stimulating nerves with electrical charge. Applications range from pacemakers and retinal implants to peripheral nerve stimulators.

[0006] Implantable electronic devices designed for FES / FNS and used intracorporeally typically contain different functional circuit areas, so-called functional blocks (FB), which serve, for example, energy management, monitoring and / or control, data storage, charge balancing, electrical voltage transformation (level shifter), as well as the detection of neuronal signals and active stimulation, to name just a few FBs.

[0007] A related circuit concept for the design and operation of a neurostimulator is explained in the article by A. Taschwer et al., “A Charge Balanced Neural Stimulator with 3.3V to 49V Supply Compliance and Arbitrary Programmable Current Pulse Shapes”, 2018 IEEE Biomedical Circuits and Systems Conference (BioCAS), Cleveland, OH, USA, 2018, pp. 1-4, doi: 10.1109 / BIOCAS.2018.8584755.

[0008] The functional block, which serves to detect and stimulate neuronal signals, is directly electrically connected to at least one organic structure via at least one electrode or electrode arrangement individually adapted to an organic structure. A known implantable electrode arrangement of this kind, which serves for the location-selective detection of neuronal electrical signals propagating along at least one nerve fiber and for the selective electrical stimulation of the at least one nerve fiber, is disclosed in EP 3204 105 B1.

[0009] The most important requirement for all nerve stimulators is patient safety, i.e. the electrical stimulation levels applied to at least one organic structure must be organically compatible; even in the event of malfunctions within the electrical circuitry inherent in the implantable electronic device, precautions must be taken to safely protect the patient.

[0010] The document DE 19951491 A1 discloses a medical device comprising a first digital signal processing system that receives at least a first analog input, wherein the first digital signal processing system has a first digital signal processor that processes data representing at least the first analog input at a first clock frequency to perform at least one first function during a predetermined period of time. Furthermore, a second digital signal processing system is provided that receives at least a second analog input, wherein the second digital signal processing system has a second digital signal processor that processes data representing at least the second analog input at a second clock frequency to perform at least one second function during the predetermined period of time.The first and second digital processing systems are constructed from circuits of a type selected from groups consisting of CMOS circuits, CML circuits, SOS circuits, SOI circuits, BICMOS circuits, PMOS circuits and NMOS circuits.

[0011] US 2014 / 0200626 A1 discloses an implantable transient nerve stimulation device for stimulating a target tissue in a patient's body, the device comprising a substrate with a circuit configured to wirelessly communicate with a controller located outside the patient's body and configured to stimulate the target tissue. The substrate and circuit are surrounded by a material configured to degrade in the patient's body.

[0012] The document EP 2 446 921 B1 describes a circuit for selecting a number of electrodes of an implantable electrode arrangement, wherein the circuit comprises a signal interface with a number of electrode and signal connections and has switching electronics with programmable switches, wherein the switches are designed as MOS transistors with charge storage.

[0013] Description of the invention

[0014] The invention is based on the object of developing an electrical circuit arrangement for a biomedical interface with electrical contacts, of which a number n of electrical contacts serves to contact at least one implantable electrode arrangement that can be attached to an organic structure, and with at least one electrical function block that is electrically connected to at least one of the n electrical contacts, in such a way that the patient risk in the event of possible malfunctions in the operation of a medically active implant that comprises the electrical circuit arrangement is to be avoided or at least significantly reduced.

[0015] The solution to the problem underlying the invention is defined in claim 1. Features that advantageously further develop the inventive concept are the subject of the dependent claims and the further description, in particular with reference to the figures.

[0016] According to the solution, an electrical circuit arrangement for a biomedical interface with the features of the preamble of claim 1 is characterized in that the at least one electrical functional block has functional elements realized by means of SOI technology, ie "silicon-on-insulator" or in German "silicon on insulator", and that the at least one electrical functional block can be operated with a supply voltage to which an electrical center potential can be assigned, which corresponds to an electrical potential assignable to the organic structure.

[0017] Each of the n electrical contacts that is directly or indirectly electrically connected to an organic structure for the purpose of stimulating and / or detecting neuronal signals or similar is simultaneously connected to at least one electrical functional block of the electrical circuit arrangement that is part of an implantable medical device, for example in the form of a neurostimulator. Each individual electrical functional block, for example responsible for measuring and detecting neuronal signals or for generating stimulation signals or for controlling and monitoring individual or all functional blocks, etc., is individually designed for different supply voltages, which in circuit arrangements of conventional design, i.e., using bulk CMOS semiconductor manufacturing technology, represent exclusively positive voltage potentials.Combining or connecting these individual supply voltages to common circuit outputs or inputs can lead to overvoltages and destructive effects, especially in fault situations. The proposed electrical circuit arrangement utilizes the advantages of SOI technology, in which the circuit elements are dielectrically isolated, reducing excess capacitance and enabling high-speed circuit operation, but with lower power at the same switching speed as with conventional circuit arrangements.In particular, SOI technology allows the use of positive and negative supply voltages, so that the individual electrical functional blocks can be operated not only with positive electrical voltages, including zero volts, as was previously the case, but with supply voltages whose voltage ranges are each limited by a minimum negative and a maximum positive voltage value. This opens up the possibility of selecting an electrical center potential for each individual electrical functional block that is characterized by the smallest possible voltage value, i.e., one that deviates slightly from zero volts, or by zero volts. Preferably, the center potentials of all electrical functional blocks of the electrical circuit arrangement are selected to be the same.

[0018] Since the electrical circuitry is part of a medical and / or functional implant, preferably an active medical implant, and its electrical contacts are connected to the body's own organic structures via suitably configured electrodes, the center potential of the supply voltages of all electrical functional blocks is selected according to the body's own organic potential. This prevents any electrical stress or irritation affecting the organic structure in the event of errors or necessary switching operations within the electrical circuitry.

[0019] A floating voltage source is used to provide the supply voltage for all electrical functional blocks of the electrical circuit arrangement, which is preferably designed as an ASIC circuit. The floating voltage source is designed either as an integral component and thus part of the circuit arrangement or as a separate component from the circuit arrangement and is connected to the circuit arrangement via at least one of the electrical contacts. Regardless of the arrangement and design of the voltage source relative to the circuit arrangement, the voltage source must be galvanically isolated from all organic structures.

[0020] Depending on the type and function of the medically active implant, the electrical circuit arrangement must be configured accordingly and equipped with the required electrical function blocks, the respective assignable functions of which can correspond to one of the following functional options:

[0021] Generation of voltage or current controlled simulation signals, detection of biomarkers, especially electrical biosignals, voltammetry, amperemetry,

[0022] Control of electromechanical assemblies,

[0023] Energy harvesting using piezoelectric, thermoelectric and / or electrochemical converter elements,

[0024] Measurement and control of the or an electrical supply voltage, electrical coupling of at least two functional blocks,

[0025] Signal output for external signal processing.

[0026] The structure and arrangement of the individual functional blocks are carried out using only components realized using SOI technology, preferably in the form of CMOS transistors or optical components.

[0027] Brief description of the invention

[0028] The invention is described below without limiting the general inventive concept by means of exemplary embodiments with reference to the drawings. In the drawings: Fig. 1 Block diagram of an implantable electrical

[0029] Circuit arrangement for controlling neuronal stimulation electrodes and

[0030] Fig. 2 Representation of supply voltages for different electrical function blocks.

[0031] Ways of implementing the invention, industrial applicability

[0032] Figure 1 shows a schematic block diagram of an electrical circuit arrangement 2 designed for an active medical implant 1, which is used, for example, for the neurostimulation of the vagus nerve.

[0033] The electrical circuit arrangement 2, which is implemented in the form of an application-specific integrated circuit (ASIC) on a chip 3, i.e., as an ASIC chip, has a plurality of different electrical functional blocks F1, F2, F3, ... Fn, which comprise functional elements implemented exclusively using SOI technology, preferably in the form of CMOS transistors or optical components. Depending on the type and function of the medical implant, the selection and arrangement of the various electrical functional blocks F1, ..., Fn, as well as their mutual interconnection on the chip 3, must be suitably coordinated.

[0034] The electrical circuit arrangement 2 has electrical contacts 4, of which a number n of electrical contacts 4 serve to contact at least one implantable electrode arrangement 6 attachable to an organic structure 5. In the example shown in Figure 1, it is assumed that the electrode arrangement 6 is designed as a wound sleeve or cuff electrode arrangement and is applied around a vagus nerve as an organic structure 5. Such an electrode arrangement 6 designed as a wound sleeve is disclosed, for example, in the document EP 3204 105 B1. The n electrical contacts 4 are connected to the electrode arrangement 6 via a conductor arrangement 7.

[0035] The number n of electrical contacts 4 of the electrical circuit arrangement 2 are, on the other hand, connected to at least one of the electrical functional blocks F1, F2, ... Fn, which in turn are connected to one another on the basis of a predetermined circuit plan.

[0036] The n electrical contacts 4 connected to at least one electrical functional block F1, ... Fn as well as to at least one electrode 6' of the electrode arrangement 6 are each designed for the maximum supply voltage of the electrical functional blocks F1, ..., Fn mounted on the chip 2. Each of the n electrical contacts 4 can be contacted with one or more electrical functional blocks in the chip 3.

[0037] For example, an electrical energy source, which is preferably designed as a floating voltage source, and a function block configured for voltage monitoring, for example F1, can be connected to one and the same electrical contact or contact pair 4, at which a maximum supply voltage of +-18 volts can be tapped or is present. An electrical function block, for example F2, which serves as a precise measuring circuit and is operated with a supply voltage of +- 0.9 volts, can be connected to a further electrical contact 4 or contact pair. Accordingly, further different supply voltages, each tailored to the function of an electrical function block Fn, can be applied to correspondingly further contacts 4. What all the different supply voltages have in common is their common reference or center potential M, which was chosen to be 0V in the above example.

[0038] The voltage diagram illustrated in Figure 2 shows the supply voltages for the electrical functional blocks F1, F2, and F3. This shows that the supply voltages of all electrical functional blocks, regardless of their different dimensions, all have the same center potential M, which preferably corresponds to the organic resting potential.

[0039] This makes it possible to enable various simultaneous combinations and reconnections between individual electrical functional blocks F1, F2, Fn and the electrical contacts 4, especially since, in the idle state in the chip 3, the same reference or center potential M, in this case 0 volts, is always present at the electrical contacts 4 and thus also at the electrical electrodes 6' in contact with the organic structure 5. Of course, it is possible to set the center potential M to something other than 0 volts, depending on the organic electrical potentials to which the electrodes 6' couple.

[0040] In this way, different electrical potentials at the electrical contacts 4, which would lead to direct currents between the individual contacts 4, can be prevented.

[0041] Since different resting potentials cannot occur between the electrical contacts, constant direct currents are avoided. Furthermore, rapid potential changes at an electrode contact do not occur, even when the functionalities are rewired. Furthermore, destructive effects at the nodes of the various electrical functional blocks can be reduced, and so-called latch-up effects can be completely eliminated.

[0042] List of reference symbols medical implant electrical circuit arrangement chip electrical contact organic structure electrode arrangement, cuff electrode' electrode conductor arrangement

Claims

Patent claims 1 . Electrical circuit arrangement for a biomedical interface, with electrical contacts, of which a number n of electrical contacts serves to contact at least one implantable electrode arrangement attachable to an organic structure, and with at least one electrical functional block which is electrically connected to at least one of the n electrical contacts, characterized in that the at least one electrical functional block has functional elements realized by means of SOI technology, and in that the at least one electrical functional block can be operated with a supply voltage to which an electrical center potential can be assigned which corresponds to an electrical potential assignable to the organic structure.

2. Electrical circuit arrangement according to claim 1, characterized in that the circuit arrangement is designed in the form of an integrated circuit, in particular in the form of an ASIC circuit.

3. Electrical circuit arrangement according to claim 1 or 2, characterized in that the circuit arrangement is part of a medical and / or functional implant.

4. Electrical circuit arrangement according to claim 3, characterized in that the medical implant is an active medical implant.

5. Electrical circuit arrangement according to claim 4, characterized in that the active medical implant serves for neurostimulation or neuromodulation.

6. Electrical circuit arrangement according to one of claims 1 to 5, characterized in that the supply voltage originates from a voltage source which is designed in the manner of a floating voltage source which is arranged and designed to be galvanically isolated from the organic structure.

7. Electrical circuit arrangement according to claim 6, characterized in that the voltage source is designed and arranged as an integral component of the circuit arrangement.

8. Electrical circuit arrangement according to claim 6, characterized in that the voltage source is designed as a separate component to the circuit arrangement and is connected to the circuit arrangement via at least one of the electrical contacts.

9. Electrical circuit arrangement according to one of claims 1 to 8, characterized in that one of the following functions can be assigned to the at least one electrical functional block: Generation of voltage- or current-controlled stimulation signals, detection of biomarkers, especially electrical biosignals, voltammetry, amperemetry, control of electromechanical assemblies Energy harvesting using piezoelectric, thermoelectric and / or electrochemical elements) Measurement and control of the or an electrical supply voltage, electrical coupling of at least two function blocks, signal output for external signal evaluation 10. Electrical circuit arrangement according to one of claims 1 to 9, characterized in that the circuit arrangement realized by means of SOI technology Functional elements represent at least one of the following components: transistors, optical components.

11. Electrical circuit arrangement according to one of claims 1 to 10, characterized in that the electrodes attachable to the organic structure are part of a cuff electrode arrangement, and that the organic structure is the vagus nerve of a living being.

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