[DIYbio] Re: Conductivity measurements with Bipolar Pulse

Hi,

I'm trying to implement a conductivity meter with the Arduino board. My
intention is to keep the electronic circuit as simple as possible.

I'm only using a voltage divider as shown:
http://www.c2o.pro.br/hackaguas/figuras/condutivimetro_00_bb.png

The alternating pulses are generated by switching the signals from pins
7 and 8 of Arduino:
http://www.c2o.pro.br/hackaguas/figuras/condutividade_efeito_frequencia_01.png


For now I'm using two steel wires as electrodes:
http://www.c2o.pro.br/hackaguas/figuras/eletrodos_00.png

My intention is to be able to control via software some measuring
parameters, such as electrode polarization time. And adjust these
parameters on the fly depending on the sample concentration range.

Recently I started to read some papers about bipolar pulse technique:
http://pubs.acs.org/doi/abs/10.1021/ac60285a015

The bipolar pulse technique for measuring solution resistance minimizes
the effects of both the series and parallel cell capacitances. The
technique consists of applying two consecutive voltage pulses of equal
magnitude and pulse width but of oposite polarity to a cell and
measuring the cell current precisely at the end of the second pulse.
(Source: Peter Kissinger, William R. Heineman, Laboratory techniques in
electroanalytical chemistry)

Does anyone has any experience with this conductivity measuring technique?

Thanks for any tip,
Markos