How to sense currents below 1 mA

I'm trying to sense a current through a line below 1 mA (at max it's 0.22 mA), how would I make this measurement either through ADC, or through a sensor with I2C or UART interface? I need a resolution of ~0.05 mA minimum. Thanks! :grin: :grin: :grin: :grin: :grin:

I think this is not a simple ask.

Current is measured by magnetic field or voltage drop. Neither of these will give a meaningful amount for the Arduino.


If the source impedance is high (i.e. a current source) then a resistor will work. A 10K resistor will produce a 2.2 V drop if 0.22 mA is passed through it. This is easily measured with the Arduino ADC.

I have assumed that putting a R in series will effect the circuit being measured.

OP please supply more information on the actual use.