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I need to achieve a -600mV bias between Vsense and Vref for a potentiostat circuit.

I'm trying to replicate the design for an Oxygen Sensor (EC410) by following the above image from the application note for design for the eletronics (https://www.sgxsensortech.com/content/uploads/2014/08/A1A-EC_SENSORS_AN2-Design-of-Electronics-for-EC-Sensors-V4.pdf).

biased sensor circuit

I've design this circuit on a protoboard, I'm using a 5V DC power supply. I have do not connected the circuit to the sensor yet because I'm affraid to damage it nor the arduino (why that is de microprocessor I'm using). And I'm using a IC TLC2274AI.

schematic

simulate this circuit – Schematic created using CircuitLab

I found this very similar question (Problem with biased circuit for oxygen sensor (SGX EC410)), but this's not the same trouble. In my case a got 1.7V from the REF, 5V from the Counter, 2.5V from the Sense, only when I connect the REF and the Count together then I got the 3.1V which I want. I'm a rookie about electronics and I don't know how to measure that Biased voltage. What I'have done was connect the probes from my multimeter between the Vss and the jumper wires Ref(1.7V), Count(5V), Sense(2.5V) and Ref+Count(3.1V). I don't know what I'm doing wrong, perhaps if I connect the sensor to de jumpers e the output to the arduino it's works fine, but like I said, I'm a rookie.

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  • \$\begingroup\$ Have you considered using an integrated solution like the Texas Instruments LMP91000, which is purpose built for applications like these? I've used it for a couple year on my gas sensing products and it has served me well. \$\endgroup\$ – vicatcu Jul 21 '18 at 0:14

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