We already reviewed this topic here: to summarize the main components: 1. Start with the Apple watch: 2. Add a temperature sensor over ESP32 to Home Assistant 3. Add an AD8232 ECG Sensor over ESP32 to Home Assistant https://how2electronics.com/iot-ecg-monitoring-ad8232-sensor-esp32/ 4. Add an ADS1115 chip for 16 bit analog to digital conversion rate https://docs.espressif.com/projects/esp-idf/en/v4.2/esp32/api-reference/peripherals/adc.html https://www.hackster.io/pukhrajdhiman/dnn-based-homemade-ecg-a4259a https://www.theengineeringprojects.com/2023/01/heartbeat-monitoring-system-with-ads1115-raspberry-pi-4.html …