Two of my own projects that were featured on Hackaday before I became a writer here include a biomedical sensor suite in Arduino shield form factor, and a simple ECG built around an AD623 ...

User [mircemk] presents his “MiliOhm Meter” project which you can build with an Arduino, a handful of common parts from your lab, and a cigar box. It doesn’t get much simpler than this, folks.

Don't worry, the coding is simple enough to understand even without prior experience. An Arduino is a much better choice than a Raspberry Pi for tasks that require real-time input and responses.