基于幻象电源供电的纯电容心音传感器的设计

目的：研制一种主要用于心脏心音信号采集的纯电容传感器。方法：采用48V幻象供电方式，把咪头摄得的微弱心音振动信号转化为电信号。通过预放大处理电路模块、屏蔽电缆和传感器前置运放电路模块把微弱的电信号放大到实际需要的电信号，然后输出到显示器件。结果：在1000Hz以下的频段，几乎不对声场产生干扰，可以测量低到20dB的声压级，上限可测量到150dB或更高的声压级，非常适合应用于心音采集。结论：该电容式传感器能正确采集到正常人的心音图．很好地反应患者的心杂音；传感器灵敏度高，频响范围宽，失真小，抗噪能力强，能适应复杂环境的心脏听诊．

Design of Pure Capacitance Phonocardiogram Sensor Based on Phantom Power Supply

Objective To researcb a pure capacitance sensor for acquisition of cardiac phonocardiogram. Methods Under the phantom power supply （48V）, the faint vibration signal of the heart was processed into electric signal by larger pretreatment circuit module, shielded cable and the sensor pre-amplifier of circuit module. Results With some experiments, it can be proved that the sensor won＇t have affect on the sound field which frequency band under 1 000Hz and can detect the level of sound field like 20dB：30dB and 150dB or higher. C, onduaion So with the sensor, the precise signal which can exactly reflect the status of patients＇ hearts can be detected, and it suits to work in complex condition for its high sensitivity, wide frequency band and low distortion.[Chinese Medical Equipment Journal,2009,30（3） ：16-17,20]