I'm wondering whether galvanometer can be used or not ?
closed as unclear what you're asking by Nick Alexeev♦ Mar 10 at 18:08
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For low current, amplifying the voltage drop across a very precise and very small sense resistor is the usual approach. A commercially available and open source implementation of that technique is the uCurrent produced by EEVBlog. It has a range switch for nA, uA, and mA.