Measurement of very low current

Hello everyone

I construct hand-made device to work with some biological sensor. That sensor got 600-800 mV of voltage and change current on line. How can I measure that current? Main problem in very low parameters - in normal tine current lays in 10-1000 nA (nano Amperes). I have working prototype (on base of Arduino Uno, MCP4725 and INA222), what simultaneously measure current and control voltage, but so tiny current INA222 cant see.

What do you advise?

Thank you

For currents that low, you will probably need a professionally designed and built instrument.

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