Finger Heartbeat Sensor Module
A KY-039 heartbeat module uses an infrared emitter and light sensor to detect changes as blood flow changes in a fingertip.
Part images
What it is
A KY-039 heartbeat module uses an infrared emitter and light sensor to detect changes as blood flow changes in a fingertip.
How students use it
Students use it for signal-smoothing practice, pulse-wave demos, and data visualization experiments.
Pins and power
Signal output, VCC, and GND on typical KY-039 modules.
Use module power that keeps the signal output inside Pico ADC limits.
Read the signal as an analog value and look for repeating peaks after filtering and steady finger placement.
Voltage and safety
Keep the analog output at or below 3.3V for Pico ADC.
Educational demo only. It is not a medical device and must not be used for health decisions.
Module internals
Main component: Optical pulse-sensing emitter and phototransistor pair.
IR emitter, phototransistor, resistors, header, and PCB.
Datasheet notes
Finger pressure, movement, ambient light, and skin contact strongly affect the signal.
Common libraries
Use machine.ADC and simple filtering/peak-detection code.
Common mistakes
Pressing too hard, moving the finger, expecting instant medical accuracy, and reading raw ADC noise without filtering.