data/text/DLP4/900225

LMP91000: Glucose sensor

Part Number: LMP91000 Hi, I am designing circuitry for a 2-electrode glucose sensor requiring bias voltage around 600mV with current typically between 2-10 nA. Measurements are conducted with DC amperometry. I am evaluating whether LMP91000 would be an appropriate choice for the potentiostat. On page 5 of the LMP91000 datasheet, "minimum operating current capability" ICE is listed as 750µA and further states "At such currents no accuracy of the output voltage can be expected". For some reason, I am having trouble understanding the meaning of this. Can you please clarify its significance and if it precludes the suitability of this AFE for my design? Thank you!

Ahanu, When reading the data sheet be a little more through and read the description about how the device works. The statement "At such currents no accuracy of the output voltage can be expected" is a note attached to the charge current of 10mA. This means that when first charging your sensor the max current may reach 10mA. The charge bias voltage cannot be controlled if max charge current is reached. The bias voltage will be ramping as if it were in current mode. Once your sensor is charged (powered up) the current will drop below 10mA and the bias voltage will return to normal. The ICE can operate between –750 μA ≤ICE ≤ 750 μA. You should not have any problems with your sensor working on the LMP91000.

Gordon, Thank you for that clarification. I had, in fact, misread the datasheet. Warm regards, -Ahanu