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.


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.
Aroom
Kevin R
KR
Department of Surgery, University of Texas Health Science Center at Houston, Houston, Texas 77030, USA.
Harting
Matthew T
MT
Cox
Charles S
CS
Radharkrishnan
Ravi S
RS
Smith
Carter
C
Gill
Brijesh S
BS
D017097:Electric Impedance; D004582:Electronics, Medical / Q000295:instrumentation*; D006801:Humans