Bioimpedance analysis: a guide to simple design and implementation.

Background: Bioimpedance analysis has found utility in many fields of medical research, yet instrumentation can be expensive and/or complicated to build. Advancements in electronic component design and equipment allow for simple bioimpedance analysis using equipment now commonly found in an engineering lab, combined with a few components exclusive to impedance analysis.

Materials And Methods: A modified Howland bridge circuit was designed on a small circuit board with connections for power and bioimpedance probes. A programmable function generator and an oscilloscope were connected to a laptop computer and were tasked to drive and receive data from the circuit. The software then parsed the received data and inserted it into a spreadsheet for subsequent data analysis. The circuit was validated by testing its current output over a range of frequencies and comparing measured values of impedance across a test circuit to expected values.

Results: The system was validated over frequencies between 1 and 100 kHz. Maximum fluctuation in current was on the order of micro-Amperes. Similarly, the measured value of impedance in a test circuit followed the pattern of actual impedance over the range of frequencies measured.

Conclusions: Contemporary generation electronic measurement equipment provides adequate levels of connectivity and programmability to rapidly measure and record data for bioimpedance research. These components allow for the rapid development of a simple but accurate bioimpedance measurement system that can be assembled by individuals with limited knowledge of electronics or programming.