医用新型高精密恒流电刺激器系统的设计

提出一种新型医用高精密恒流电刺激器系统的整体方案，可作为诱发电位的电刺激器，也可用作功能式神经肌肉电刺激器。针对高精密恒流电刺激器对刺激电压高伏值和刺激电流高精确度的设计要求，电源设计部分采用推挽升压后再倍压整流得到一个平稳的360 V高压，同时电路中的12 bit D/A和运放组成的恒流源电路可以保证一个高质量的脉宽低于10 μs、最大100 mA恒定电流的产生。针对高精密恒流电刺激器的高人体安全系数的要求，对电路中的控制信号、反馈信号和通信信号采用光电隔离，并对供电电源采用DC-DC电源隔离屏蔽；同时设计了过流保护电路、脉宽限制电路和脉宽检错电路，结合底层硬件保护和上层脉宽检错电路的双重安全保护措施，大大提高了刺激器的安全系数。系统硬件电路的仿真和实际测试结果证明该设计方案的可行性和可靠性可满足临床医疗检测的要求。

The Design of a New Type Constant Current Clinical Stimulator with High Precision

The purpose of this paper is to illustrate a new scheme for a new medical high-precision constant current electric stimulator system. Methods: According to the design requirements of stimulation voltage of high-voltage and stimulation current of high-precision, the power supply adopts push-pull boost and then double-voltage rectification to obtain a stable 360 V high voltage. The 12 bit D/A and op amp constant current source circuit in the circuit could ensure that a high-quality pulse width is less than 10 μs and a maximum constant current is 100 mA. As for the high human safety factor, the control signals, the control signals, the feedback signals and the communication signals in the circuit are isolated by digital isolation, and the power supply is shielded by DC-DC power supply. At the same time, the over-current protection circuit, the pulse width limiting circuit and the pulse width error detection circuit are designed. Results: According to the high-amplitude voltage, high-precision current and high-safety factor of the human body, a system can be designed, which can be used as an electric stimulator for evoked potential or as a functional neuromuscular electrical stimulator. Conclusion: The feasibility and reliability of the system are proved by the hardware circuit simulation diagram and the actual test results. Concurrently, the intensity, frequency and pulse width of the stimulation current reach higher precision, the electric stimulation evoked potential waveform is clear, and the noise is small. Significance: The scheme of this new type of medical high-precision constant current stimulator system has been proved to meet the requirements of clinical medical examination.