A fast cochlear implant neural telemetry circuit and system

Abstract

The present invention discloses a fast cochlear implant neural telemetry circuit and system. The circuit includes a stimulation generator, a signal amplifier, an analog-to-digital converter, and a data calculation memory. The stimulation generator resets the charge in the neural tissue to zero before the stimulation starts and ends, and the interval between two consecutive stimulations of the same electrode can be adjusted arbitrarily; the signal amplifier filters and amplifies the neural impulse signal received by the acquisition electrode due to the electrical stimulation; the analog-to-digital converter can adjust the sampling frequency and the opening delay, and is connected to the signal amplifier to perform analog-to-digital conversion on the amplified analog signal; the data calculation memory is connected to the analog-to-digital converter to calculate and store the data after the analog-to-digital conversion. The present invention reduces the artifacts of neural telemetry by improving the stimulation circuit, can flexibly control the key parameters of neural telemetry, improve the neural telemetry extraction rate, and greatly improves the speed of neural telemetry by calculating and storing the data.

Description

Technical Field

[0001] The invention belongs to the field of implantable medical devices, and in particular relates to a fast artificial cochlear nerve telemetry circuit and system. Background Art

[0002] Cochlear implant neural telemetry technology refers to the collection of electrical stimulation induced potentials generated by the stimulation of the cochlear implant using the internal circuit of the cochlear implant on the designated non-stimulating electrode after stimulation of the designated electrode. Since this technology does not require other auxiliary equipment and has the advantages of direct and convenient effects, neural telemetry has become an important reference for doctors to judge whether the implant is successful during surgery and for the adjustment process of young children who do not have subjective feedback ability.

[0003] In the actual implementation process, since the neural response signal is very weak, it is easy to be interfered by artificial electrical stimulation artifacts and other noises, which makes it very difficult to collect accurate neural response signals. Forward masking subtraction is the most commonly used method in cochlear implant telemetry technology. It is mainly based on the principle that the nerve will not respond to any electrical stimulation for a period of time after a stimulation. It introduces four conditions: detection stimulation (A), masking + detection stimulation (B), masking stimulation (C) and no stimulation (D). The data of the four conditions are calculated by A-B+CD, and then averaged several times to obtain the final neural response waveform. This algorithm has high requirements for the cochlear implant telemetry circuit. It needs to be able to flexibly control the time interval between masking and detection stimulation, the time for eliminating the offset of the amplifier circuit, the sampling frequency of the analog-to-digital conversion circuit, and the startup delay. In addition, a relatively large disadvantage of this algorithm is that it is relatively slow, especially requiring a large amount of two-way communication from the PC to the implant, which causes inconvenience to doctors during surgery and children adjusting the machine. Summary of the invention

[0004] In view of this, the purpose of the present invention is to provide a fast cochlear implant neural telemetry circuit and system. The use of this circuit can reduce the interference of stimulation artifacts on neural responses, and improve the success rate of neural telemetry by flexibly adjusting the interval between two stimulations, the interval for DC charge zeroing between electrodes, the time for amplifier offset elimination, and the sampling frequency and opening delay of the analog-to-digital converter. By performing addition and subtraction operations on the analog-to-digital conversion signals according to certain rules, storing the data after the addition and subtraction operations, and finally sending the data to an in vitro debugging device at one time, the speed of neural telemetry is greatly improved.

[0005] To achieve the above object, the present invention provides a fast cochlear implant neural telemetry circuit, which at least includes: a stimulation generator, a signal amplifier, an analog-to-digital converter and a data calculation memory, wherein:

[0006] The stimulation generator includes a stimulation control module, a stimulation control timer, switches S1 and S2, and an AC stimulation module, wherein:

[0007] The stimulation control module is connected to the AC stimulation module and switches S1 and S2, and generates an AC stimulation current between the stimulation electrode and the loop electrode of the AC stimulation module through digital signal control and returns the charges at both ends to zero after the stimulation ends;

[0008] The stimulation control timer is connected to the stimulation control module and is used to time the interval between two consecutive stimulations performed by the stimulation control module on the same electrode;

[0009] The switch S1 is connected to the stimulation electrode, and the switch S2 is connected to the loop electrode. Before and after the stimulation, the switches S1 and S2 are closed and connected to a fixed electrical level at the same time.

[0010] The AC stimulation module generates an AC stimulation current between the stimulation electrode and the loop electrode, and the amplitude and pulse width of the stimulation current are controlled by the stimulation control module;

[0011] The signal amplifier includes a low-pass filtering module, an offset elimination amplification module and an offset elimination timer, wherein:

[0012] The low-pass filter module is connected to the stimulation electrode and the loop electrode to filter out high-frequency noise from the received tiny nerve impulse signal;

[0013] The offset elimination amplification module is connected to the low-pass filtering module to amplify the output signal of the low-pass filtering module, and the module eliminates its own offset signal;

[0014] The offset elimination timer and the offset elimination amplification module are eliminated to control the offset elimination time;

[0015] The analog-to-digital converter includes an analog-to-digital conversion circuit, a frequency division circuit and a start timer, wherein:

[0016] The analog-to-digital conversion circuit is connected to the offset cancellation amplification module to perform analog-to-digital conversion on the amplified signal;

[0017] The frequency division circuit is connected to the analog-to-digital conversion circuit and is used to control the sampling rate of the analog-to-digital conversion circuit;

[0018] The start timer is connected to the analog-to-digital conversion circuit and is used to control the start delay of the analog-to-digital conversion circuit;

[0019] The data calculation memory includes a primary data register, a calculator and a calculation data register, wherein:

[0020] The primary data register is connected to the analog-to-digital conversion circuit to store the data generated by the analog-to-digital conversion circuit;

[0021] The calculator is connected to the primary data register and the calculation data register, performs corresponding addition and subtraction operations on the data in the primary data register and the calculation data register according to the cochlear implant nerve telemetry algorithm, and retains the operation results in the calculation data register.

[0022] Preferably, the switches S1 and S2 are automatically opened before the stimulation starts, and automatically closed after the stimulation ends, so as to eliminate stimulation artifacts and residual DC charge residues between electrodes.

[0023] Preferably, the timing range of the stimulation control timer is 100 to 1000 microseconds.

[0024] Preferably, the sampling rate of the analog-to-digital conversion circuit can vary between 10K and 10 MHz.

[0025] Preferably, the startup delay range of the analog-to-digital conversion circuit is 0 to 500 microseconds.

[0026] Preferably, the measurement accuracy of the analog-to-digital conversion circuit is 6 to 18 bits.

[0027] Based on the above purpose, the present invention also provides a rapid cochlear implant neural telemetry system, which also includes PC application software, a forward transmission module, a command decoding module, a reverse transmission module and a reverse demodulation module, wherein:

[0028] The PC application software is connected to the forward transmission module and the reverse demodulation module, and sends the command parameters of the neural telemetry to the fast cochlear implant neural telemetry circuit through the forward transmission module, and / or graphically displays the data sent back by the reverse demodulation module, so that the user can obtain a clear neural response waveform;

[0029] The forward transmission module is connected to the command decoding module by wireless transmission, and the neural telemetry parameters set by the PC application software are coded, modulated and transmitted;

[0030] The command decoding module is connected to the rapid cochlear neural telemetry circuit and is used to control the stimulation control module, the stimulation control timer, the imbalance elimination timer, the start timer, the frequency division circuit and the calculator;

[0031] The reverse transmission module is connected to the calculation data register, and is used to modulate the data in the calculation data register and transmit it reversely to the outside of the body;

[0032] The reverse demodulation module is connected to the reverse transmission module by wireless induction, demodulates and digitizes the data transmitted by the reverse transmission module, and transmits the data to the PC application software.

[0033] The beneficial effects of the present invention are as follows: by improving the stimulation generator circuit, the interference of stimulation artifacts on neural responses is reduced; by flexibly adjusting the interval between two stimulations, the time for amplifier offset elimination, and the sampling frequency and opening delay of the analog-to-digital converter, the success rate of neural telemetry extraction is improved; by performing addition and subtraction operations on the analog-to-digital conversion signals according to certain rules, storing the data after the addition and subtraction operations, and finally sending the data at one time to an in vitro debugging device, the speed of neural telemetry is greatly improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to make the purpose, technical solution and beneficial effects of the present invention clearer, the present invention provides the following drawings for illustration:

[0035] Figure 1 It is an overall block diagram of a specific application example of the fast cochlear implant nerve telemetry circuit of the embodiment of the present invention;

[0036] Figure 2 A specific block diagram of a specific application example in the rapid cochlear implant nerve telemetry system of an embodiment of the present invention;

[0037] Figure 3 It is a diagram illustrating the principle of forward masking subtraction in a specific application example of a fast cochlear implant neural telemetry circuit according to an embodiment of the present invention;

[0038] Figure 4 A graph of nerve response signals at different stimulation intervals in a specific application example of a rapid cochlear implant nerve telemetry system according to an embodiment of the present invention;

[0039] Figure 5 This is a comparison diagram of ADC startup time and DC charge zeroing control waveform in a specific application example of a fast cochlear implant nerve telemetry system according to an embodiment of the present invention. DETAILED DESCRIPTION

[0040] The preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0041] See also Figure 1-2 , which is an overall block diagram of a fast cochlear implant neural telemetry circuit 10 and a specific block diagram of a system 100 according to an embodiment of the present invention, wherein:

[0042] A fast cochlear implant neural telemetry circuit 10 includes at least: a stimulation generator 110, a signal amplifier 120, an analog-to-digital converter 130 and a data calculation memory 140, wherein:

[0043] The stimulation generator 110 includes a stimulation control module 111, a stimulation control timer 112, switches S1 and S2, and an AC stimulation module 113, wherein:

[0044] The stimulation control module 111 is connected to the AC stimulation module 112 and the switches S1 and S2, and generates an AC stimulation current between the stimulation electrode and the loop electrode of the AC stimulation module 112 through digital signal control and returns the charges at both ends to zero after the stimulation ends;

[0045] The stimulation control timer 113 is connected to the stimulation control module 111 and is used to time the interval between two consecutive stimulations performed by the stimulation control module 111 on the same electrode;

[0046] The switch S1 is connected to the stimulation electrode, and the switch S2 is connected to the loop electrode. Before and after the stimulation, the switches S1 and S2 are closed and connected to a fixed electrical level at the same time.

[0047] The AC stimulation module 112 generates an AC stimulation current between the stimulation electrode and the loop electrode, and the amplitude and pulse width of the stimulation current are controlled by the stimulation control module 111;

[0048] The signal amplifier 120 includes a low-pass filter module 121, an offset elimination amplification module 122 and an offset elimination timer 123, wherein:

[0049] The low-pass filter module 121 is connected to the stimulation electrode and the loop electrode to filter out high-frequency noise of the received tiny nerve impulse signal;

[0050] The offset elimination amplification module 122 is connected to the low-pass filtering module 121, and amplifies the output signal of the low-pass filtering module 121. The module can eliminate its own offset signal;

[0051] The offset elimination timer 123 is eliminated from the offset elimination amplification module 122 and is used to control the offset elimination time;

[0052] The analog-to-digital converter 130 includes an analog-to-digital conversion circuit 131, a frequency division circuit 132 and a start timer 133, wherein:

[0053] The analog-to-digital conversion circuit 131 is connected to the offset cancellation amplifier module 122 to perform analog-to-digital conversion on the amplified signal;

[0054] The frequency division circuit 132 is connected to the analog-to-digital conversion circuit 131 and is used to control the sampling rate of the analog-to-digital conversion circuit;

[0055] The start timer 133 is connected to the analog-to-digital conversion circuit 131 and is used to control the start delay of the analog-to-digital conversion circuit;

[0056] The data calculation memory 140 includes a primary data register 141, a calculator 142 and a calculation data register 143, wherein:

[0057] The primary data register 141 is connected to the analog-to-digital conversion circuit 131 to store the data generated by the analog-to-digital conversion circuit 131;

[0058] The calculator 142 is connected to the primary data register 141 and the calculation data register 143 , performs corresponding addition and subtraction operations on the data in the primary data register 141 and the calculation data register 143 according to the cochlear implant nerve telemetry algorithm, and retains the operation results in the calculation data register 143 .

[0059] For the above purpose, see Figure 2 The present invention also provides a rapid cochlear implant neural telemetry system 100, which also includes PC application software 20, a forward transmission module 30, a command decoding module 40, a reverse transmission module 50 and a reverse demodulation module 60, wherein:

[0060] The PC application software 20 is connected to the forward transmission module 30 and the reverse demodulation module 60, and can send the command parameters of the neural telemetry to the fast cochlear implant neural telemetry circuit 10 through the forward transmission module 30, and can also graphically display the data sent back by the reverse demodulation module 60, so that the user can obtain a clear neural response waveform;

[0061] The forward transmission module 30 is connected to the command decoding module 40 by wireless transmission, and the neural telemetry parameters set by the PC application software 20 are coded, modulated and transmitted;

[0062] The command decoding module 40 is connected to the rapid cochlear neural telemetry circuit 10 and is used to control the stimulation control module 111, the stimulation control timer 113, the imbalance elimination timer 123, the start timer 133, the frequency division circuit 132 and the calculator 142;

[0063] The reverse transmission module 50 is connected to the calculation data register 143, and is used to modulate the data in the calculation data register 143 and transmit it to the outside of the body in reverse direction;

[0064] The reverse demodulation module 60 is connected to the reverse transmission module 50 via wireless induction, demodulates and digitizes the data transmitted by the reverse transmission module 50 , and transmits the data to the PC application software 20 .

[0065] Furthermore, the rapid cochlear implant nerve telemetry circuit is characterized in that the switches S1 and S2 are automatically disconnected before the stimulation starts and automatically closed after the stimulation ends, thereby eliminating stimulation artifacts and residual DC charge residues between electrodes.

[0066] Furthermore, the fast cochlear implant neural telemetry circuit is characterized in that the timing range of the stimulation control timer 113 is 100 to 1000 microseconds.

[0067] Furthermore, the fast cochlear implant neural telemetry circuit is characterized in that the sampling rate of the analog-to-digital conversion circuit 131 can vary between 10K and 10 MHz.

[0068] Furthermore, the fast cochlear implant nerve telemetry circuit is characterized in that the start-up delay range of the analog-to-digital conversion circuit 131 is 0 to 500 microseconds.

[0069] Furthermore, the fast cochlear implant nerve telemetry circuit is characterized in that the measurement accuracy of the analog-to-digital conversion circuit 131 is 6 to 18 bits.

[0070] Figure 3 This is a diagram illustrating the principle of forward masking subtraction in a specific application example of the fast cochlear implant neural telemetry circuit 10 of the embodiment of the present invention. In the figure, SE represents the stimulation waveform of the stimulating electrode, RE represents the waveform received by the receiving electrode, Probe is the detection stimulation waveform, Mask is the masking stimulation waveform, PA is the artifact waveform caused by the detection stimulation waveform, PN is the neural response waveform caused by the detection stimulation, MA is the artifact caused by the masking stimulation waveform, and MN is the neural response waveform caused by the masking stimulation. In case A, the cochlear implant performs a detection stimulation; in case B, the cochlear implant performs a masking stimulation and a detection stimulation successively, and the time node of the detection stimulation is the same as that of case A; in case C, the cochlear implant performs a masking stimulation, and the time node of the masking stimulation is the same as that of case B; in case D, the cochlear implant does not stimulate; by receiving the signals in the four cases respectively, using the principle that the nerve will not react to the second stimulation under two rapid and continuous stimulations, performing A-B+CD calculations and averaging multiple times, the influence of PA, MA and system background noise on cochlear implant neural telemetry can be eliminated in the end. The calculator 142 performs corresponding addition and subtraction operations on the primary data register 141 and the calculation data register 143 according to the forward masked subtraction algorithm, and stores the result in the calculation data register 143. After multiple operations are completed, the calculation result is pushed out at one time, which greatly improves the speed of neural telemetry.

[0071] Figure 4 This is a neural response signal diagram under different stimulation intervals in a specific application example of the rapid cochlear implant neural telemetry system of the embodiment of the present invention. Due to the different neural response times and the different second stimulation incapacity times of different individuals, the neural stimulation interval (IPI) needs to be flexibly adjusted in neural telemetry practice. Figure 4The figure shows different neural telemetry signals received when the neural stimulation interval is from 420 microseconds to 630 microseconds using the fast cochlear implant neural telemetry system 100, where the horizontal axis is time (100 microseconds / grid) and the vertical axis is voltage value (50 microvolts / grid). From the comparison in the figure, it can be seen that the neural telemetry signals measured at different neural stimulation intervals are different. In this patient, when the IPI is 510 microseconds, the amplitude of the neural response signal reaches the maximum value.

[0072] Figure 5 This is a comparison diagram of ADC startup time and DC charge zeroing control waveform of a specific application example in the fast cochlear implant nerve telemetry system of an embodiment of the present invention, wherein the horizontal axis is time (300 microseconds / grid) and the vertical axis is voltage value (100 microvolts / grid). Figure 5 (a) is the small signal waveform obtained under normal conditions. Figure 5 (b) is the small signal waveform obtained by delaying the ADC start time by 200 microseconds. Figure 5 Comparing (a), we can see that the waveform is truncated by 200 microseconds. Figure 5 (c) is the small signal waveform obtained by extending the DC charge zeroing time by 200 microseconds, which is similar to Figure 5 (a) Comparison: In the first 200 microseconds, since the stimulation electrode is connected to the return electrode at this time, the received small signal waveform is a flat line.

[0073] The circuit of the present invention reduces the interference of stimulation artifacts on neural responses, improves the success rate of neural telemetry extraction by flexibly adjusting the interval between two stimulations, the interval for returning DC charges between electrodes to zero, the time for amplifier offset elimination, and the sampling frequency and opening delay of the analog-to-digital converter, performs addition and subtraction operations on analog-to-digital conversion signals according to certain rules, stores the data after the addition and subtraction operations, and finally sends the data to an in vitro debugging device at one time, thereby greatly improving the speed of neural telemetry. The entire circuit has the advantages of strong adaptability and easy integration.

[0074] Finally, it should be noted that the above preferred embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail through the above preferred embodiments, those skilled in the art should understand that various changes can be made in form and details without departing from the scope defined by the claims of the present invention.

Claims

1. A fast cochlear implant neural telemetry circuit, characterized in that: At least: Stimulus generator, signal amplifier, analog-to-digital converter and data calculation memory, wherein, The stimulation generator includes a stimulation control module, a stimulation control timer, switches S1 and S2, and an AC stimulation module, wherein: The stimulation control module is connected to the AC stimulation module and switches S1 and S2, and generates an AC stimulation current between the stimulation electrode and the loop electrode of the AC stimulation module through digital signal control and returns the charges at both ends to zero after the stimulation ends; The stimulation control timer is connected to the stimulation control module and is used to time the interval between two consecutive stimulations performed by the stimulation control module on the same electrode; The switch S1 is connected to the stimulation electrode, and the switch S2 is connected to the loop electrode. Before and after the stimulation, the switches S1 and S2 are closed and connected to a fixed electrical level at the same time. The AC stimulation module generates an AC stimulation current between the stimulation electrode and the loop electrode, and the amplitude and pulse width of the stimulation current are controlled by the stimulation control module; The signal amplifier includes a low-pass filtering module, an offset elimination amplification module and an offset elimination timer, wherein: The low-pass filter module is connected to the stimulation electrode and the loop electrode to filter out high-frequency noise from the received tiny nerve impulse signal; The offset elimination amplification module is connected to the low-pass filtering module to amplify the output signal of the low-pass filtering module, and the module eliminates its own offset signal; The offset elimination timer and the offset elimination amplification module are eliminated to control the offset elimination time; The analog-to-digital converter includes an analog-to-digital conversion circuit, a frequency division circuit and a start timer, wherein: The analog-to-digital conversion circuit is connected to the offset cancellation amplification module to perform analog-to-digital conversion on the amplified signal; The frequency division circuit is connected to the analog-to-digital conversion circuit and is used to control the sampling rate of the analog-to-digital conversion circuit; The start timer is connected to the analog-to-digital conversion circuit and is used to control the start delay of the analog-to-digital conversion circuit; The data calculation memory includes a primary data register, a calculator and a calculation data register, wherein: The primary data register is connected to the analog-to-digital conversion circuit to store the data generated by the analog-to-digital conversion circuit; The calculator is connected to the primary data register and the calculation data register, performs corresponding addition and subtraction operations on the data in the primary data register and the calculation data register according to the cochlear implant nerve telemetry algorithm, and retains the operation results in the calculation data register.

2. The fast cochlear implant neural telemetry circuit according to claim 1, characterized in that: The switches S1 and S2 are automatically opened before the stimulation starts, and automatically closed after the stimulation ends, thereby eliminating stimulation artifacts and residual DC charge residues between electrodes.

3. The fast cochlear implant neural telemetry circuit according to claim 1, characterized in that: The timing range of the stimulation control timer is 100 to 1000 microseconds.

4. The fast cochlear implant neural telemetry circuit according to claim 1, characterized in that: The sampling rate of the analog-to-digital conversion circuit varies between 10K and 10MHz.

5. The fast cochlear implant neural telemetry circuit according to claim 1, characterized in that: The start-up delay range of the analog-to-digital conversion circuit is 0 to 500 microseconds.

6. The fast cochlear implant neural telemetry circuit according to claim 1, characterized in that: The measurement accuracy of the analog-to-digital conversion circuit is 6 to 18 bits.

7. A system using the fast cochlear implant neural telemetry circuit according to any one of claims 1 to 6, characterized in that: It also includes PC application software, forward transmission module, command decoding module, reverse transmission module and reverse demodulation module, among which, The PC application software is connected to the forward transmission module and the reverse demodulation module, and sends the command parameters of the neural telemetry to the fast cochlear implant neural telemetry circuit through the forward transmission module, and / or graphically displays the data sent back by the reverse demodulation module, so that the user can obtain a clear neural response waveform; The forward transmission module is connected to the command decoding module by wireless transmission, and the neural telemetry parameters set by the PC application software are coded, modulated and transmitted; The command decoding module is connected to the rapid cochlear neural telemetry circuit and is used to control the stimulation control module, the stimulation control timer, the imbalance elimination timer, the start timer, the frequency division circuit and the calculator; The reverse transmission module is connected to the calculation data register, and is used to modulate the data in the calculation data register and transmit it reversely to the outside of the body; The reverse demodulation module is connected to the reverse transmission module by wireless induction, demodulates and digitizes the data transmitted by the reverse transmission module, and transmits the data to the PC application software.

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