I am working on a 3 Lead amperometric cell in Potentiostat configuration (CE, RE and WE) and I found the word "Biased sensor" and "Bias voltage" all over the datasheet. My question is:

  • What is a biased sensor ?
  • Why shall we inject a Bias voltage in a biased sensor ?

Link: http://www.ti.com/lit/ds/symlink/lmp91000.pdf

  • \$\begingroup\$ Same words mean different things in different context, you should add a link to the datasheet if possible, or quote some relevant text to give us a bit more stuff to work with. \$\endgroup\$ – Arsenal Jul 25 '18 at 9:12
  • \$\begingroup\$ A data sheet link is necessary. \$\endgroup\$ – Andy aka Jul 25 '18 at 9:13
  • \$\begingroup\$ Edited. I added the link \$\endgroup\$ – Pryda Jul 25 '18 at 9:41

From Design of Electronics for Electrochemical Gas Sensors:

For sensors which have 3 electrodes, (the majority of sensors for detecting toxic gases and EC410 Oxygen sensor), the circuit required is known as a potentiostatic circuit. This circuit can either have the sensing and reference electrodes at the same potential (non-biased) or the sensing and reference held at different voltages (a biased sensor).


The purpose of the sensor bias circuit (potentiostat) is to maintain the potential of the sensing electrode at a constant level with respect to the reference electrode. This is done by adjusting the voltage of a third ‘counter’ electrode.

As to why one would do that, I think you might need to ask over on Chemistry.SE, however, for the case of an SGX EC410 oxygen sensor, user Viktor Scherf wrote in a comment that:

The bias voltage is needed for chemical redaction of oxygen.


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