近年来，脑成像与脑调控技术发展迅速，但当前脑调控技术主要是开环模式，若要观测脑调控技术对大脑的影响机制，只能分开进行。在进行脑神经刺激时需要临床医生根据观察到的治疗效果和积累的经验选择刺激参数，采集也仅在刺激开始之前或结束之后进行操作，开环脑神经刺激带来的局限变得越来越明显。将采集和刺激设备结合起来，形成一个闭环系统，通过实时检测脑神经活动状态，当检测到特定标志信号后，及时调整神经刺激参数，这将能够克服开环脑神经调控研究中的局限性。

本论文主要研究内容和工作如下：

首先，研制了多通道经颅电刺激与多模态生理信号采集硬件电路。多通道指所有通道电极均可自由调整刺激参数且相互独立输出；多模态包括脑电信号、脉搏信号，以及通过脉搏波计算得到的心率、血氧、血压等指标。优化了采集模块的模拟前端电路，提高了采集动态范围；设计了针对采集刺激两用的电源电路和隔离电路，实现了良好的电气隔离和数字隔离；设计了一款采集刺激一体式主动电极，通过内部模拟开关实现采集刺激两种电路的切换；加入了脉搏信号检测电路，实现脑电采集的同时采集指尖的脉搏信号，为后续心脑协同化研究打下基础；设计了多通道独立输出电流源电路，搭配通道选择电路，可实现各通道独立输出电流，为脑部全局刺激打下基础；优化了阻抗检测方案，搭配采集电路，实现相得益彰的效果。

其次，实现了系统的软件设计。编写了采集系统和刺激系统的固件程序；升级了采集系统的上位机显示界面，增加了脉搏显示通道和刺激功能；设计了刺激控制软件，对各通道电流输出的配置更加方便与直观；编写了心率变异性的时域、频域算法，对比挑选出最具鲁棒性的时域算法；实现了幅度阈值触发刺激的控制算法；验证并复现了血氧饱和度、收缩压算法；优化了脑电采集通信协议，提出了电刺激通信协议。

最后，完成了系统测试和实验验证。针对脑电采集模块设计了一种自动化测试工装，提供了一套基于国家计量标准的测试方案；完成了脑电采集模块主要性能指标的测试，测试结果均符合国家计量标准；开展了阻抗、信噪比、电流耐受性三种实验，从多种常见电极材料中择优选取出最适合作采集刺激两用的电极；对多通道经颅电刺激模块的输出精度和带负载能力进行测试；设计了Alpha波触发实验，验证了系统闭环的可行性。

综上所述，本论文的研究内容围绕一款多通道经颅电刺激与多模态生理信号采集一体式系统的研制展开。系统包括采集刺激硬件模块，显示、控制上位机软件，心率、血氧检测算法，刺激触发算法。

In recent years, the development of brain imaging technology is in full swing, and the development of brain regulation technology is in the ascendant. Unfortunately, the current brain nerve stimulation is mainly open-loop mode. Observing the mechanisms by which brain regulation affects the brain can only be done separately. For example, when performing cranial nerve stimulation, clinicians need to select stimulation parameters according to the observed therapeutic effect and accumulated experience, and the acquisition can only be performed before or after the stimulation starts. The limitations brought about by open-loop brain nerve stimulation are becoming more and more more obvious. If the acquisition and stimulation equipment are combined to form a closed-loop system, by detecting the state of brain nerve activity in real time, and adjusting the nerve stimulation parameters in time after a specific signal is detected, this will be able to overcome the limitations of open-loop brain nerve stimulation research.

The main research content and work of this paper are as follows:

First, Developed multi-channel transcranial electrical stimulation and multi-modal physiological signal acquisition hardware circuit. Multi-channel means that all channel electrodes can freely adjust stimulation parameters and output independently of each other; multi-modality includes EEG signal, PPG signal, and heart rate, blood oxygen, blood pressure, etc. calculated by PPG. The analog front-end circuit of the acquisition module is optimized to improve the dynamic range of acquisition; the power supply circuit and isolation circuit for both acquisition and stimulation are designed to achieve good electrical isolation and digital isolation; an acquisition and stimulation integrated active Electrodes, through the internal analog switch to realize the switching of the acquisition and stimulation circuits; adding the PPG signal detection circuit to realize the EEG acquisition and the PPG signal of the fingertips at the same time, laying the foundation for the subsequent construction of the brain-heart collaboration integrated system; designed Multi-channel independent output current source circuit, combined with channel selection circuit, can realize independent output current of each channel, laying the foundation for distributed stimulation; optimized impedance detection scheme, combined with acquisition circuit, to achieve complementary effects.

Secondly, Realized the software design of the system. Compiled the firmware programs of the acquisition system and the stimulation system; upgraded the display interface of the host computer of the acquisition system, and added PPG display channels and stimulation functions; designed the stimulation control software to make the configuration of the current output of each channel more convenient and intuitive; wrote the The time-domain and frequency-domain algorithms of heart rate variability were compared to select the most robust time-domain algorithm; the blood oxygen saturation and systolic blood pressure algorithms were verified and reproduced; Realized the control algorithm of amplitude threshold trigger stimulation; the EEG acquisition communication protocol was optimized, and electrical stimulation was proposed letter of agreement.

At last, Completed the system test and experimental verification. An automated test tool was designed for the EEG acquisition module, and a set of test schemes based on national measurement standards was provided; the test of the main performance indicators of the EEG acquisition module was completed, and the test results were in line with the national measurement standards; impedance, signal Three experiments of noise ratio and current tolerance, selecting the most suitable electrode for acquisition and stimulation from a variety of common electrode materials; testing the output accuracy and load capacity of the multi-channel transcranial electrical stimulation module; An alpha-wave triggering experiment is designed to verify the feasibility of the closed-loop system.

In summary, the research content of this paper revolves around the development of an integrated system for multi-channel transcranial electrical stimulation and multi-modal physiological signal acquisition. The system includes acquisition and stimulation hardware modules, display and control host computer software, heart rate and blood oxygen detection algorithms.