Broadband excitation for short-time impedance spectroscopy.
Frequency domain impedance measurements are still the common approach in assessing passive electrical properties of cells and tissues. However, due to the time requirements for sweeping over a frequency range for performing spectroscopy, they are not suited for recovering fast impedance changes of biological objects. The use of broad bandwidth excitation and monitoring the response as a function of time will greatly reduce the measurement time. The widespread usage of a square wave excitation is simple but not always the best choice. Here we consider different waveforms for excitation and discuss not only the advantages but also their limitations. Measurements in a miniaturized chamber where frequency and time domain measurements are compared show the suitability of different waveforms as excitation signals for the measurements of bio-impedance. The chirp excitation has been found to be most promising in terms of frequency range, signal-to-noise ratio and crest factor.
Min
M
M
Department of Electronics, Tallinn University of Technology, Tallinn, Estonia. min@elin.ttu.ee
Pliquett
U
U
Nacke
T
T
Barthel
A
A
Annus
P
P
Land
R
R
D017097:Electric Impedance; D044085:Microfluidics; D013057:Spectrum Analysis / Q000379:methods*; D013997:Time Factors