From the MobilECG webpage:
MobilECG is an USB-based open source 12-lead clinical electrocardiograph.
It is designed to meet all the relevant medical standards (ISO 60601-1, etc.).
Smaller than most ECGs on the market, and also has superior signal quality.
Works with PCs, notebooks, and Android tablets. Records all leads simultaneously.
This enterprise went open source after their fund raising campaign didn’t achieve the funds they wanted. In a noble move the creators decided that this shouldn’t be a reason for this project to be left in a shelf somewhere. Now everyone can download plans, code and work with it.