Development of Implanted Microprocessor-Based Biosignal Monitoring System and Direct Recording of Biosignal inside the Body

人体内部存在着多种生物电信号，如神经元脉冲信号或血流速度等生物力学信号，直接记录这些信号对研究生物机制或疾病病因具有重要意义。本研究的目标是开发一种基于植入式微处理器的生物信号监测系统，该系统由传感器、刺激电极、存储器、微处理器和通信接口等记录生物信号所需的最小元素组成，并建立记录和分析体内发生的生物信号的方法。为实现该植入式生物信号监测站，本研究探讨了该植入式系统应具备的条件。主要的问题是，植入体内的电脑系统和休眠的电源是否能被体外的主机电脑通过红外通信控制。结果表明，通过串行通信可以很好地控制隔离计算机系统，如监控程序的下载、记录数据的上传以及外围电路的检查。系统休眠时的电流消耗约为1mA。尺寸可以通过表面贴装技术缩小到名片尺寸。此外，本系统的开发目的是作为一种动态监测设备。在这里，心率的动态监测，身体活动和姿势可以成功地记录在日常生活中。

Inside the body there exist many kinds of bioelectric signal such as neuron impulse or the biomechanical signal such as blood flow velocity, and the direct recording of these signals is very important for the investigation of the biomechanism or the cause of disease.The goal of this study is to develop an implanted microprocessor-based biosignal monitoring system constituting of minimum elements necessary to record biosignals such as sensors, stimulation electrode, memories, microprocessor and communication interface, and to establish the method to record and analyze biosignals occurring inside the body.To realize this implanted biosignal monitoring station the condition which this implanted system should have has been inverstigated in this study. The main problem is whether the computer system implanted inside the body and sleeping for the power down can be controlled by the host computer outside the body through infra-red communication or not.Results show that the isolated computer system can be perfectly controlled through serial communication such as the download of monitoring program, the upload of the recorded data and the check of the peripheral circuits. The consumption of current is about 1mA when this system is sleeping. The size can be downsized by the surface mount technique into the name card size.Moreover this system developed here was clarified to be used as an ambulatory monitoring device. Here an ambulatory monitoring of the heart rate, the physical activity and the posture can be successfully recorded in daily life.