The BioAmp by Upside Down Labs can help! The project is open source hardware and the design files are available at upsidedownlabs/BioAmp_v1.5:

BioAmp v1.5 is a single chip Bio-potential amplifier for recording any Bio-potential signal non-invasively. It’s compatible with Backyard Brains Spike Recorder, which you can use to record and visualize all the Bio-potential signals.

Originally tweeted by Upside Down Labs (@myupsidedownlab) on March 17, 2021.