Design of a Programmable Bioelectrical Impedance System for Biomedical Applications

The design of a portable,versatile and programmable bioelectrical impedance system is presented. The device uses in expensive off-the-shelf components to perform multi-frequency current injection and voltage measurements through skin electrodes. The impedance measurement system can be configured as multi-frequency bioelectrical impedance analyzer as well as acupuncture point detector, for localizing pathologically changed acupuncture points on the body. In order to improve the accuracy and the flexibility of the measurements, a programmable wide frequency band width current source has been designed. It allows to generate sinusoidal and square wave forms with a frequency up to 1 MHz and amplitude values in the range of [12 mu A(pp)-1.2mA(pp)]. The measured signals can be amplified with a programmable gain and converted with 16 bits of resolution before being transmitted to a PC through USB transmission for further processing.