CN102824169A - Implantable neural signal recording system based on body channel transmission technology - Google Patents

Abstract

An implantable nerve signal recording system based on body channel transmission, comprising: a nerve signal recording microelectrode; a nerve signal preprocessing circuit, the input end of which is connected to the nerve signal recording microelectrode to complete the collection and conversion of the nerve signal in the body It is a digital signal; an internal transmitter, whose input terminal is connected with the output terminal of the nerve signal preprocessing circuit; a first signal transmission contact electrode, which is connected with the output terminal of the internal transmitter; a second signal transmission contact electrode; An external receiver, whose input end is connected with the second signal transmission contact electrode; a computer, whose input end is connected with the output end of the external receiver, to receive and process the input signal of the external receiver. The present invention uses the body channel as a signal transmission medium, and does not need to connect the implanted device in the body with the equipment outside the body through a metal connection, which can avoid wound infection caused by wired connection; Tissue benefits while extending battery life in implanted systems.

Description

Implantable neural signal recording system based on bulk channel transmission technology

technical field

The invention belongs to the field of electronic technology, in particular to an implantable nerve signal recording system based on body channel transmission technology.

Background technique

Real-time recording of human neuron activity is of great significance for both scientific research and clinical medicine. At present, many kinds of nerve signal recording microelectrodes have been designed in academia. These electrodes are implanted into the body to extract nerve signals. The extracted nerve signals are directly connected to external devices through metal wires to realize signal transmission. In medical applications, the transmission method that directly connects electrodes implanted in the body to external devices through metal wires is prone to infection. In addition, this method generally anesthetizes the subject, so it is difficult to record the neural signals of a freely moving person in a non-anesthetized state, and it cannot be recorded for a long time.

Another method is to integrate nerve recording microelectrodes and signal processing circuit modules together and implant them in the body, and the signals are sent to external devices through radio frequency transmission. The use of radio frequency transmission can solve the problem of metal wire transmission, but the power consumption of transmission is high, and excessive heat generated by internal circuits can easily cause tissue damage, and it is also susceptible to interference from other radio frequency signals.

Utilizing the characteristics of conductors and electrolytes in the human body, the use of body channel transmission can not only solve the problem of metal wire transmission, but also achieve low-power transmission, reduce the damage caused by heat generation to tissues, and prolong the battery life of the implanted system. It is not easily disturbed by the surrounding environment, which makes it possible to record long-term neural signals under free activities.

Contents of the invention

The object of the present invention is to provide an implantable nerve signal recording system based on body channel transmission technology, which uses body channel as the signal transmission medium, and does not need to connect the implanted device in the body with the device outside the body through a metal connection , which can avoid wound infection caused by wired connection; compared with wireless data communication technologies such as Bluetooth, the implant system based on body channel transmission has lower power consumption and less heat generation, which is beneficial to implant tissues and can prolong The lifespan of the implanted system battery.

The present invention provides an implantable neural signal recording system based on body channel transmission, comprising:

A nerve signal recording microelectrode;

A nerve signal preprocessing circuit, the input end of the nerve signal preprocessing circuit is connected with the nerve signal recording micro-electrode to complete the acquisition of the nerve signal in the body and convert it into a digital signal;

An internal transmitter, the input end of the internal transmitter is connected to the output end of the nerve signal preprocessing circuit;

a first signal transmission contact electrode, the first signal transmission contact electrode is connected to the output terminal of the internal transmitter;

a second signal transmission contact electrode;

An external receiver, the input end of which is connected to the second signal transmission contact electrode;

A computer, the input terminal of the computer is connected with the output terminal of the external receiver, and receives and processes the input signal of the external receiver.

Description of drawings

In order to further illustrate the technical content of the present invention, the following detailed description is as follows in conjunction with the embodiments and accompanying drawings, wherein:

Figure 1 is a simplified equivalent circuit diagram of a cell or tissue;

Fig. 2 is a schematic diagram of a neural signal recording system;

Fig. 3 is a neural signal preprocessing circuit structural diagram;

Fig. 4 is a transmitter circuit structure diagram;

Fig. 5 is a circuit structure diagram of the in vitro receiver.

Detailed ways

The human body has the characteristics of conductors and electrolytes. H.Kanai proposed a simplified equivalent circuit of cells or tissues, as shown in Figure 1. Among them, Cm is the cell membrane capacitance, Ri is the intracellular resistance, and Re is the extracellular resistance. The electrical conductivity of the human body can be utilized to use the human body as a waveguide to transmit the electrical signals recorded by the implantable neural signal recording system.

Please refer to Fig. 2-shown in Fig. 5, the present invention provides a kind of implantable neural signal recording system (in Fig. 2) based on body channel transmission, comprising:

A nerve signal recording microelectrode 10, the nerve signal recording microelectrode 10 adopts a Utah plate microelectrode array, the electrode has excellent biocompatibility, can be implanted for a long time and remains stable. There are multiple recording points on the nerve signal recording microelectrode 10, and electrical signals at multiple points can be collected simultaneously. For the sake of illustration, it is assumed here that there are four recording points a, b, c, and d, corresponding to four nerve signals (see Figure 2). One of the points is set as the reference potential, for example, the potential at point a is set as the reference potential, and both the nerve signal preprocessing circuit 11 and the body transmitter 12 use the potential of this point as the reference potential.

A nerve signal preprocessing circuit 11 (referring to Fig. 3), the input terminal of this nerve signal preprocessing circuit 11 is connected with the nerve signal recording microelectrode 10, finishes the collection of the nerve signal in the body and converts it into a digital signal, wherein the nerve signal preprocessing circuit 11 includes:

Multi-channel analog front-end signal conditioning circuit 111, an analog multiplexer 112, the analog multiplexer 112 receives the input signal of the multi-channel analog front-end signal conditioning circuit 111, an analog-to-digital converter 113, the analog-to-digital converter 113 The input terminal of is connected to the output terminal of analog multiplexer 112. The number of multi-channel analog front-end signal conditioning circuits 111 in this nerve signal preprocessing circuit 11 is 4-32 roads, and each road analog front-end signal conditioning circuit 111 includes a capacitor coupling amplifier 1111 and a filter 1112 connected therewith. The capacitive coupling amplifier 1111 in the preprocessing circuit 11 amplifies the nerve signal through capacitive coupling, which can filter out the DC drift introduced by the electrode-electrolyte interface. The capacitive coupled amplifier 1111 has a fully differential structure, and the low-frequency cut-off point is adjustable, which has the advantages of low noise and low power consumption. The filter 1112 in the nerve signal preprocessing circuit 11 is a fourth-order Bessel filter with a fully differential structure and adjustable bandwidth, and the filter 1112 is a cascade of four-stage fully differential switched capacitor filters. The sampling frequency of the analog-to-digital converter 113 that is higher than 0.5 times, that is, the out-of-band signal and noise higher than fs/2 is effectively suppressed by the filter 1112, so as to ensure that there is no frequency component higher than fs/2 in the signal to avoid undershooting The aliasing phenomenon caused by sampling improves the signal-to-noise ratio of the analog-to-digital converter 113 . By controlling the analog multiplexer 112 in the nerve signal preprocessing circuit 11, the number of nerve signal recording channels can be changed to realize single-channel nerve signal recording or time-division multiplexing of multiple nerve signal recordings. The analog-to-digital converter 113 in the neural signal preprocessing circuit 11 is a fully differential structure, and has a successive approximation analog-to-digital converter with the function of processing multi-channel neural signals in real time, and adopts the successive approximation analog-to-digital converter with medium speed, medium precision, With the comprehensive advantages of low power consumption and small area, the number of bits of the analog-to-digital converter 113 is designed to be higher than 8 bits, which can meet the requirements of the dynamic range and noise of the input signal.

An internal transmitter 12 (referring to Fig. 4), the input end of this internal transmitter 12 is connected with the output end of nerve signal preprocessing circuit 11, this internal transmitter 12 comprises: an encoder 121, a modulation circuit 122, adopts frequency The mode of key shift modulation, the input end of this modulation circuit 122 is connected with the output end of encoder 121, a driver 123, the input end of this driver 123 is connected with the output end of modulation circuit 122;

A first signal transmission contact electrode 13, the first signal transmission contact electrode 13 is connected to the output end of the internal transmitter 12, and transmits the electrical signal of the internal transmitter 12 to the human body through skin coupling.

A second signal transmission contact electrode 15, which detects electrical signals coupled to the human body through skin contact;

An external receiver 16 (referring to Fig. 5), the input end of this external receiver 16 is connected with the second signal transmission contact electrode 15, and this external receiver 16 comprises: a demodulation circuit 161, adopts frequency shift keying demodulation mode, a decoder 162, the input end of the decoder 162 is connected to the output end of the demodulation circuit 161, and a digital processing module 163, the input end of the digital processing module 163 is connected to the output end of the decoder 162.

A computer 17, the input terminal of the computer 17 is connected with the output terminal of the external receiver 16, and receives and processes the input signal of the external receiver 16. Developing a corresponding user interface interface on the computer 17 can realize real-time display of data, storage of data and further processing.

The working process of the implantable neural signal recording system based on bulk channel transmission is as follows:

Typical nerve signal amplitude is 50μV-5mV, frequency is 1Hz-10kHz, based on the dynamic range of nerve signal frequency and amplitude, and nerve signal recording microelectrode 10 and the surrounding environment of neurons are easy to introduce noise, so nerve signal recording The nerve signal collected by the microelectrode 10 should first be amplified and out-of-band noise suppressed by the nerve signal preprocessing circuit 11 .

The signal processed by the nerve signal preprocessing circuit 11 is transmitted to the internal transmitter 12 . At the transmitting end of the body transmitter 12, the electrical signal is loaded to the skin through the first signal transmission contact electrode 13 in a galvanic coupling manner, and the body is used as a waveguide to transmit the recorded electrical signal. Outside the body, the second signal transmission contact electrode 15 detects the signal transmitted from the body to the human skin, and the external receiver 16 demodulates and digitally processes the electrical signal detected by the second signal transmission contact electrode 15 and then transmits it to the external computer 17 Display, storage and subsequent data processing. In this way, the collected nerve signals are transmitted from the body to the outside by using the human body itself as a transmission medium.

The implantation process of the implantable neural signal recording system based on bulk channel transmission is as follows:

Firstly, a model based on bulk channel transmission is established, and biomaterials with similar conductivity and electrolyte properties to human skin tissue are selected to establish a bulk channel transport model. Using this body channel transmission model, the internal transmitter 12, the first signal transmission contact electrode 13, the second signal transmission contact electrode 15 and the external receiver 15 are first tested to evaluate the acceptable heat generation of skin tissue and the implantation system. power to determine the proper transmission distance.

After determining the appropriate transmission distance, in vitro debugging of the entire system is carried out. After the in vitro debugging of the whole system is completed, the system including the nerve recording microelectrode 10, the nerve signal preprocessing circuit 11, the internal transmitter 12, the first signal transmission contact electrode 13 and the power supply battery is implanted in the body. The second signal transmission contact electrode 15 is in contact with the skin outside the body according to the test obtained in the previous experiment, and then connected to the receiving electrode 16 outside the body and the computer 17 .

The above is only a specific implementation mode in the present invention, but the scope of protection of the present invention is not limited thereto. Anyone familiar with the technology can easily think of changes or replacements within the technical scope disclosed in the present invention. All should be covered within the scope of the present invention. Therefore, the protection scope of the present invention should be determined by the protection scope of the claims.

Claims (9)

1. An implantable neural signal recording system based on body channel transmission, comprising: A nerve signal recording microelectrode; A nerve signal preprocessing circuit, the input end of the nerve signal preprocessing circuit is connected with the nerve signal recording micro-electrode to complete the acquisition of the nerve signal in the body and convert it into a digital signal; An internal transmitter, the input end of the internal transmitter is connected to the output end of the nerve signal preprocessing circuit; a first signal transmission contact electrode, the first signal transmission contact electrode is connected to the output terminal of the internal transmitter; a second signal transmission contact electrode; An external receiver, the input end of which is connected to the second signal transmission contact electrode; A computer, the input terminal of the computer is connected with the output terminal of the external receiver, and receives and processes the input signal of the external receiver. 2. The implantable neural signal recording system based on body channel transmission as claimed in claim 1, wherein the neural signal preprocessing circuit comprises: Multi-channel analog front-end signal conditioning circuit, an analog multiplexer, the analog multiplexer receives the input signal of the multi-channel analog front-end signal conditioning circuit, an analog-to-digital converter, the input terminal of the analog-to-digital converter is connected to the analog multiplexer The output terminal of the road selector is connected. 3. The implantable neural signal recording system based on bulk channel transmission according to claim 2, wherein the number of multi-channel analog front-end signal conditioning circuits is 4-32. 4. The implantable neural signal recording system based on bulk channel transmission as claimed in claim 2, wherein each analog front-end signal conditioning circuit comprises a capacitively coupled amplifier and a filter connected thereto. 5. The implantable neural signal recording system based on body channel transmission as claimed in claim 1, wherein the body transmitter comprises: an encoder, a modulating circuit, the input end of the modulating circuit is connected with the output end of the encoder , a driver, the input end of the driver is connected to the output end of the modulation circuit. 6. The implantable neural signal recording system based on body channel transmission as claimed in claim 1, wherein the external receiver comprises: a demodulation circuit, a decoder, the input terminal of the decoder and the demodulation circuit The output end is connected to a digital processing module, and the input end of the digital processing module is connected to the output end of the decoder. 7. The implantable neural signal recording system based on bulk channel transmission as claimed in claim 2, wherein the capacitive coupling amplifier in the neural signal preprocessing circuit is a fully differential structure, and the low-frequency cut-off point is adjustable. 8. The implantable neural signal recording system based on bulk channel transmission as claimed in claim 2, wherein the filter in the neural signal preprocessing circuit is a fully differential structure, and the bandwidth is an adjustable fourth-order Bessel filter . 9. The implantable neural signal recording system based on bulk channel transmission as claimed in claim 2, wherein the analog-to-digital converter in the neural signal preprocessing circuit is a fully differential structure, with successive approximation of real-time processing multi-channel neural signal function analog-to-digital converter.

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