Electrocardiography for Cheap: DIY ECG Uses One LM741 Op-Amp, Five Resistors, and 'Penny Electrodes' « Adafruit Industries – Makers, hackers, artists, designers and engineers!
Check Your Heart Condition Under 10$ || DIY Homemade ECG Machine using AD8232 - YouTube
Citizen Science — DIY ECGs - Make:
DIY ECG with AD8232 and Sound Card - YouTube
The Do-It-Yourself Electrocardiogram | SpringerLink
Build Your Own ECG-EKG Unit | Nuts & Volts Magazine