Hello everyone,
The project is a type of LAB instrument that requires low ohm measurement to find resistivity of the conducting material. And the precision is my concern to a better job. For now 1% is quite sufficient, but I would like to do better later.
And I don't know of any type of calibration house facilty that can do this kinda work. Most of these facilities just check the final device and make sure their specifications are correct. Also they are mostly for the the marketable products.
Even though I started the project on Arduino UNO board, but currently I am using a lot of extra components (as suggested here) and arduino is just calculating the result. So I don't mind adding a precise voltage regulator for reference, if needed.
raschemmel ,sir, your suggestions of current sense resistors are very good, but currently I think I will test using the 0.5Ohm(0.5%) and 0.1Ohm(0.1%) from vishay. But I will definitely keep them in mind.
About temperature concern, even if the device work accurately in a fixed temperature range, is currently fine by me. We can add temperature sensors later on after a few tests, if necessary.
Lastly, I have started working on the board, will probably post feedback in a day.
Thanks.