Based upon an electrocardiogram circuit we made for a university project, introducing the Raspberry Pi Pico into the circuit with it's 12-bit Successive Approximation Register (SAR-type) Analog to Digital Converter (ADC).

The circuit includes Op-Am based Low Pass and High Pass Filters to prevent movement artifacts (ie. breathing) or noise becoming a problem. Op-Amp Amplifiers amplify the signal to workable 0-3.3V levels for the Pico to read.

Although still a work in progress, the aim is to use this circuit to display heart rate on the PC, with the Pico's USB interface. It's low current at standby allows minimal power consumption, especially great for portability applications. Possibility to make this wireless with a wifi module (ESP32 or RP2040 Connect).