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Testing miniaturized electrodes for impedance measurements within the β-dispersion – a practical approach

Abstract

Miniaturized electrodes are introduced in life sciences in a great number and variety. They are often designed for a special purpose without the need of quantitative analysis, such as for detecting cells or water droplets in a fluid channel. Other developments aim in monitoring a single quantity in a process where all other factors held constant.

To use miniaturized electrodes for quantitative measurements, their behavior should be known in detail and stable over time in order to allow a mathematical correction of the data measured.

Here we show test procedures for evaluating macroscopic but also microscopic electrodes. The most important quality parameters for electrode systems used in life science are the electrode impedance, its stability, the useful frequency range as well as the limits for applied stimulus without driving the electrode system into a non-linear region of the current/voltage relation. Proper electrode design allows a bandwidth from 100 Hz up to some MHz for impedances ranging over decades from 50 Ω up to several MΩ.

Open access
Biomass measurement of living Lumbriculus variegatus with impedance spectroscopy

be applied for online-monitoring; It is a non-destructive method and hence can be used for measuring living organisms. The objectives of this work are to measure mass, size and diet-based distinguishability (differences, variations) of the aquatic worms Lumbriculus variegatus using impedance spectroscopy. Materials and methods Impedance Analysis All measurements were performed using an Impedance/Gain Phase Analyzer HP 4194A (Hewlett-Packard, California, U.S.A) which was connected via four BNC cables to a BDS 1200 connection head containing a BDS

Open access
Optically isolated current source

29 6 S173 – 84 2008 http://dx.doi.org/10.1088/0967-3334/29/6/S15 7 Uwe Pliquett, Markus Schönfeldt, Andreas Barthel, Dieter Frense, Thomas Nacke, and Dieter Beckmann. Front end with offset-free symmetrical current source optimized for time domain impedance spectroscopy. Physiological measurement 32(7):927–44, 2011. http://dx.doi.org/10.1088/0967-3334/32/7/S15 21646715 10.1088/0967-3334/32/7/S15 Uwe Pliquett Markus Schönfeldt Andreas Barthel Dieter Frense Thomas Nacke Dieter Beckmann Front end with offset-free symmetrical current

Open access