Multichannel bipolar current source used in electrical impedance spectroscopy: Preliminary results

Abstract

Electrical Impedance Spectroscopy (EIS) is a method used to characterize biological materials. Mostly EIS systems consist of applying a multifrequency sinusoidal current of constant amplitude in the material and measuring the resulting potential to calculating the transfer impedance. It is necessary to assure that the injecting current has constant amplitude over a wide frequency range. Some EIS systems use multichannel circuits to allow measurements covering a wide area. However, multiplexing system introduces undesirable capacitances in the EIS method. The objective of this work is to investigate the stray capacitance effects in an 8-channel bi-polar current source used in EIS system. It also investigates the load effects. It was compared the measured load current to the output currents at source and sink side of the bipolar current source. The results showed that stray currents are high at higher frequencies and that the load affects the stray currents. It can be concluded that is very important know the exact current flowing in the load in order to assure accuracy measurements and then to improve EIS systems. © 2009 Springer-Verlag.