一种高精度生物电阻抗测量系统的设计  

Design of a high precision bio-impedance measurement system

作　　者：霍旭阳[1] 尤富生[1] 史学涛[1] 杨国胜[1] 董秀珍[1] 曹亮[1] 

机构地区：[1]第四军医大学生物医学工程系医学电子工程教研室,西安710032

出　　处：《仪器仪表学报》2007年第6期994-998,共5页Chinese Journal of Scientific Instrument

基　　金：国家自然科学基金重点项目(50337020)资助

摘　　要：设计了一种生物电阻抗测量系统,用于无创测量颅内血肿、水肿引起的电阻抗变化。该系统采用直接数字频率合成技术(DDS)设计高精度、频率可调的正弦激励电流源,采用正交序列数字解调法提取电阻抗的信息,并对解调结果进行软件补偿。所实现的电阻抗测量系统可工作于5～300kHz,在全频率范围内,系统具有80dB以上的共模抑制比(CMRR),对100Ω电阻的相对测量精度达到-90dB。采用颅内注射50μl自体血的方法,建立大鼠颅内出血动物模型,初步的动物实验表明,该系统可以检测到相应的电阻抗变化。A bio-impedance measurement system was designed to monitor non-invasively the electrical impedance change of brain caused by intracranial hematoma, ischaemia and edema. The direct digital frequency synthesizer （DDS） technique is used to produce a high accuracy and frequency adjustable sine wave current excitation source. The impedance information is extracted by orthogonal sequential digital demodulation method, and is equalized by software. The impedance measurement system can work in a wide frequency range from 5 kHz to 300 kHz. Its common mode rejection ratio （CMRR） is higher than 80 dB, and the relative measurement accuracy for a 100Ω resistor reaches - 90 dB in the full bandwidth. A model of the intracerebral hemorrhage was established by infusing 50 μl of the autologous artery blood into the encephalic of rats. Preliminary animal experiments prove that the corresponding electrical impedance change can be detected by this measurement system.

关 键 词：生物电阻抗 直接数字频率合成 数字解调 

分 类 号：R318[医药卫生—生物医学工程]