Bio-impedance Detection Using AD5933 Impedance Converter Analyzer

The biomedical devices are playing major role in diagnosis of diseases, analysis of physiological processes and transferring the medical data all over the world. Analyzing the impedance of biological samples has gained importance in the last decade. Presently all the bio-impedance analyzer available in the market are heavy and costly. In this paper, an attempt has made to develop a portable, low cost bio-impedance analyzer. The main aim of this paper is to detect the human Bio impedance using AD5933 Impedance Converter Analyzer that can be used to diagnose various diseases like skin cancer, viral fevers and so on. This paper is based on the prototype of bio-impedance measurement system using AD5933 of Analog Devices, ARM LPC2148 low power MCU and unique disposable strip electrode system. Impedance converter generates excitation signal, which is applied to tissue under study (TUS) through electrodes. The response signal from TUS is measured using different electrode pair and processed internally in impedance converter to obtain real and imaginary values. These values are obtained at each sweeping frequency and transferred to ARM LPC2148 MCU trough I2C interface. ARM LPC2148 is low power MCU, useful to develop portable or battery operated system. For further processing the data is transferred to PC through USB interface. The developed device was successfully operated in a frequency range of 100 Hz to 1 MHz to measure impedance of various samples. The prototype operates from 100Hz - 1MHz and covers the impedance range of 1k - 10 M in four sub ranges. It is also capable of measuring of 100 to 1k with additional circuitry. The system is operated from a PC and the software required for operation and control has developed. The main target of these systems is personal and home monitoring.