US-12616829-B2 - Synchronized sample-and-hold stimulation artifact removal for real-time closed-loop electrical stimulation and recording device

US12616829B2US 12616829 B2US12616829 B2US 12616829B2US-12616829-B2

Abstract

A real-time closed-loop electrical stimulation and recording device includes an electrical stimulator, a processor, two or more sample-and-hold protection circuits, and an analog front-end amplifier. The electrical stimulator is connected to a physiological tissue. The processor controls the protection circuits to sample and hold the first voltage of an analog physiological signal from a physiological tissue before the electrical stimulator generates a stimulation signal. The processor controls the protection circuits to block the analog physiological signal after the protection circuits hold the first voltage. The processor controls the protection circuits to sample and hold the second voltage of the analog physiological signal that replace the first voltage from the physiological tissue after the stimulation signal ends. The amplifier amplifies the first voltage or the second voltage to generate a detection signal and transmit the detection signal to the processor.

Inventors

Ming-Dou Ker
Chung-Yu Wu
Chi-Wei Huang

Assignees

NATIONAL YANG MING CHIAO TUNG UNIVERSITY

Dates

Publication Date: 20260505
Application Date: 20231219

Claims (10)

1 . A real-time closed-loop electrical stimulation and recording device, configured to be connected to a physiological tissue, comprising: an electrical stimulator configured to be connected to the physiological tissue; a processor connected to the electrical stimulator and configured to drive the electrical stimulator to generate a stimulation signal applied to the physiological tissue; two or more sample-and-hold protection circuits configured to be connected to the physiological tissue and the processor, wherein the processor controls the sample-and-hold protection circuits to sample and hold a first voltage of an analog physiological signal from the physiological tissue before the electrical stimulator generates the stimulation signal, the processor controls the sample-and-hold protection circuits to block the analog physiological signal after the sample-and-hold protection circuits hold the first voltage, and the processor controls the sample-and-hold protection circuits to sample and hold a second voltage of the analog physiological signal that replaces the first voltage from the physiological tissue after the stimulation signal ends; and an analog front-end amplifier connected to the sample-and-hold protection circuits and the processor and configured to receive and amplify the first voltage or the second voltage to generate a detection signal and transmit the detection signal to the processor.
2 . The real-time closed-loop electrical stimulation and recording device according to claim 1 , wherein each of the sample-and-hold protection circuits is connected to a grounding terminal, the processor couples each of the sample-and-hold protection circuits to a grounding voltage of the grounding terminal after each of the sample-and-hold protection circuits samples and holds the first voltage, the physiological tissue is decoupled to the grounding voltage when the sample-and-hold protection circuits blocks the analog physiological signal, and the processor decouples the sample-and-hold protection circuits to the grounding voltage when the sample-and-hold protection circuits sample and hold the second voltage.
3 . The real-time closed-loop electrical stimulation and recording device according to claim 2 , wherein the sample-and-hold protection circuit comprises: a first electrical switch and a capacitor connected in series, wherein the capacitor is connected between the analog front-end amplifier and the first electrical switch, a control terminal of the first electrical switch is connected to the processor, and the first electrical switch is configured to be connected between the physiological tissue and the capacitor; a second electrical switch connected between a node and the grounding terminal, the node is configured to be connected between the physiological tissue and the first electrical switch, and a control terminal of the second electrical switch is connected to the processor; and at least one third electrical switch configured to be connected between the node and the physiological tissue, and a control terminal of the at least one third electrical switch is connected to the processor; wherein when the processor turns on the first electrical switch and the at least one third electrical switch and turns off the second electrical switch, the capacitor samples and holds the first voltage or the second voltage through the first electrical switch and the at least one third electrical switch and the node is decoupled to the grounding voltage; wherein when the processor turns off the first electrical switch and the at least one third electrical switch and turns on the second electrical switch, the first electrical switch and the at least one third electrical switch block the analog physiological signal, the node is coupled to the grounding voltage, and the physiological tissue is decoupled to the grounding voltage.
4 . The real-time closed-loop electrical stimulation and recording device according to claim 3 , wherein the first electrical switch is an N-channel metal-oxide-semiconductor field-effect transistor (NMOSFET) and the second electrical switch is an N-channel metal-oxide-semiconductor field-effect transistor (NMOSFET) or a P-channel metal-oxide-semiconductor field-effect transistor (PMOSFET).
5 . The real-time closed-loop electrical stimulation and recording device according to claim 3 , wherein, the at least one third electrical switch is an N-channel metal-oxide-semiconductor field-effect transistor (NMOSFET) for blocking a positive voltage or a P-channel metal-oxide-semiconductor field-effect transistor (NMOSFET) for blocking a negative voltage.
6 . The real-time closed-loop electrical stimulation and recording device according to claim 3 , wherein the at least one third electrical switch comprises an N-channel metal-oxide-semiconductor field-effect transistor (NMOSFET) and a P-channel metal-oxide-semiconductor field-effect transistor (NMOSFET) connected in series.
7 . The real-time closed-loop electrical stimulation and recording device according to claim 1 , wherein the analog front-end amplifier comprises: a gain stage connected to the sample-and-hold protection circuits and configured to receive and amplify the first voltage or the second voltage to generate a physiological amplified signal; a programmable bandwidth stage coupled to the gain stage and configured to receive the physiological amplified signal and select and output a middle frequency component of the physiological amplified signal; and an analog-to-digital converter (ADC) connected to the programmable bandwidth stage and the processor and configured to receive the middle frequency component of the physiological amplified signal, perform analog-to-digital conversion on the middle frequency component of the physiological amplified signal to generate the detection signal, and transmit the detection signal to the processor.
8 . The real-time closed-loop electrical stimulation and recording device according to claim 1 , wherein the stimulation signal comprises a negative pulse voltage or a positive pulse voltage.
9 . The real-time closed-loop electrical stimulation and recording device according to claim 1 , wherein the stimulation signal comprises a negative pulse voltage and a positive pulse voltage that sequentially occur.
10 . The real-time closed-loop electrical stimulation and recording device according to claim 1 , further comprises a conductor with isolators and electrodes, wherein the conductor is configured to be arranged in the physiological tissue, the isolators and the electrodes are alternately arranged, the electrodes are respectively connected to the electrical stimulator and the sample-and-hold protection circuits and commonly configured to be connected to the physiological tissue.

Description

BACKGROUND OF THE INVENTION Field of the Invention The invention relates to a synchronized sample-and-hold stimulation artifact removal recording and stimulation device, particularly to a real-time closed-loop electrical stimulation and recording device. Description of the Related Art A closed-loop biomedical electrical stimulation system includes an analog front-end physiological signal amplifier for measuring neural signals and a stimulator circuit for generating electrical stimulation. The closed-loop biomedical electrical stimulation system monitors the patient's neural signal characteristics as the basis for closed-loop control while applying high-voltage stimulation. With the evolution of integrated circuit processes, the required power supply voltage for the circuit gradually decreases. However, the withstand voltage of the components also decreases. High-voltage stimulation generates stimulation noise that contaminates the measured neural signals. High voltage larger than the withstand voltage of the component may cause irreversible damage to circuits, thereby affecting functionality or shortening the circuit's lifespan. It is known that the analog front-end physiological signal amplifier adopts an input protection circuit to block stimulation noise. It disconnects the amplifier from the electrode during stimulation to prevent stimulation noise from entering the amplifier. However, it can only block positive voltage stimulation. During the blocking period, the brainwave signal in the moment of stimulation cannot be observed. Also, after the blocking period ends, a longer recovery time is needed for the physiological signal amplifier to return to its normal operation, resulting in significant waveform distortion. In addition to the foregoing techniques, additional hardware circuits or software methods are used to obtain the waveform contaminated by stimulation noise from the output of the signal amplifier, obtain the stimulation noise from the contaminated waveform, and transmit the obtained stimulation noise to the input of the signal amplifier for counteraction based on negative feedback compensation. Therefore, additional hardware circuits and software methods are required to perform this function, causing a great amount of computational power consumption. The method can only separate stimulation noise with the same features. If the noise characteristics change, it is unable to eliminate the noise completely and prevent output saturation and component damage caused by excessive stimulation noise. SUMMARY OF THE INVENTION The invention provides a real-time closed-loop electrical stimulation and recording device, which avoids the output saturation or component damage of an amplifier caused by excessive voltage during high-voltage stimulation, reduces signal loss and nonlinear distortion caused by blocking a stimulation signal, and effectively blocks noise contamination caused by electrical stimulation without requiring a great amount of additional power consumption. The closed-loop electrical stimulation device can be easily applied and integrated into a system or a system-on-chip (SoC) using various processes rather than specialized high-voltage withstanding processes. In an embodiment of the invention, a real-time closed-loop electrical stimulation and recording device is connected to a physiological tissue and provided. The closed-loop electrical stimulation device includes an electrical stimulator, a processor, two or more sample-and-hold protection circuits, and an analog front-end amplifier. The electrical stimulator is connected to the physiological tissue. The processor is connected to the electrical stimulator and configured to drive the electrical stimulator to generate a stimulation signal applied to the physiological tissue. The sample-and-hold protection circuits are connected to the physiological tissue and the processor. The processor controls the sample-and-hold protection circuits to sample and hold the first voltage of an analog physiological signal from the physiological tissue before the electrical stimulator generates the stimulation signal. The processor controls the sample-and-hold protection circuits to block the analog physiological signal after the sample-and-hold protection circuits hold the first voltage. The processor controls the sample-and-hold protection circuits to sample and hold the second voltage of the analog physiological signal that replace the first voltage from the physiological tissue after the stimulation signal ends. The analog front-end amplifier is connected to the sample-and-hold protection circuits and the processor and configured to receive and amplify the first voltage or the second voltage to generate a detection signal and transmit the detection signal to the processor. In an embodiment of the invention, each of the sample-and-hold protection circuits is connected to a grounding terminal. The processor couples each of the sample-and-hold protection