ECG Heart Monitor with AD8232 and OLED Waveform Display

The heart's electrical activity is a millivolt-level signal buried in noise — mains hum, muscle artifacts and electrode motion all dwarf it, which is why measuring it cleanly is a genuine instrumentation challenge. The AD8232 was designed exactly for this: an integrated analog front-end with an instrumentation amplifier, filters and lead-off detection for single-lead ECG. This project builds a working heart monitor around it: disposable electrodes feed the AD8232, an Arduino samples the conditioned signal, an OLED draws the scrolling ECG trace in real time, and firmware detects R-peaks to compute beats per minute. The student sees their own PQRST complex appear on the display, measures their own heart rate, and writes a report on the signal chain that produced it — with the explicit, honest boundary that this is a teaching prototype, not clinical equipment.

1. Three disposable electrodes are placed on the chest/arms per the guide; skin preparation reduces contact impedance.
2. The AD8232 amplifies the differential biopotential (instrumentation amplifier), applies high-pass filtering to remove baseline drift and low-pass filtering to remove high-frequency noise.
3. The Arduino's ADC samples the conditioned analog output at approximately 200 Hz.
4. Firmware draws the samples as a scrolling waveform on the OLED while a peak-detection algorithm identifies R-peaks.
5. Heart rate is computed from the R-R interval over a rolling window and shown on the display.
6. If an electrode detaches, the AD8232 lead-off detection flags it and the display shows a lead-off warning.

Tech stack:

• AD8232 single-lead ECG front-end module
• Arduino Nano (ATmega328P)
• 0.96-inch OLED display (live waveform)
• Disposable ECG electrodes + snap leads
• R-peak detection firmware
• Serial logging for report plots
• Arduino IDE (C/C++ firmware)

• [AD8232 analog front-end] Integrated instrumentation amplifier with high-pass and low-pass filtering extracts the millivolt ECG signal from electrode noise.
• [Live OLED waveform] The Arduino samples the conditioned signal and draws a scrolling real-time ECG trace on a 0.96-inch OLED.
• [Heart-rate calculation] Firmware detects R-peaks with a threshold algorithm and computes BPM over a rolling window, displayed beside the trace.
• [Lead-off detection] The AD8232's lead-off pins flag a detached electrode; the display shows a clear warning instead of a flat line.
• [Right-leg-drive noise rejection] The AD8232's driven-reference output reduces mains interference, demonstrating a real biomedical noise-rejection technique.
• [Serial ECG logging] Raw samples stream over serial for plotting the PQRST complex in the report.
• [Electrode placement guide] Documented three-electrode placement with skin-preparation notes the student follows for clean traces.

• Working ECG monitor prototype (AD8232 module, Arduino, OLED, electrode leads)
• Arduino firmware with waveform plot, BPM and lead-off handling
• Wiring diagram and electrode-placement guide
• Skin-preparation and noise-reduction notes
• Project report PDF (ECG physiology basics, instrumentation amplifiers, filtering, sample traces template)
• PPT presentation for final review
• Viva Q&A preparation document

• Educational prototype only — NOT a medical device; it must never be used for diagnosis, screening or any clinical decision. This boundary is stated in the report.
• Single-lead only; it cannot produce the 12-lead views a clinician uses.
• Trace quality depends on electrode contact, skin preparation and stillness — motion artifacts are expected and documented as a limitation.
• Mains interference is reduced, not eliminated; the demo works best away from heavy electrical noise.
• Heart-rate is computed from a simple threshold algorithm; arrhythmia detection is explicitly out of scope.
• Disposable electrodes are consumables and must be replaced between subjects for hygiene.