Olimex SHIELD-EKG-EMG-PASSIVE ECG EMG Passive Electrode Pack

The DRL electrode is a key component for active noise cancellation in biopotential measurements. It connects to a feedback circuit on the Olimex shield that injects an inverted version of the common-mode noise picked up by the body back into the right leg. This technique dramatically improves the Common-Mode Rejection Ratio (CMRR), resulting in cleaner, more stable ECG and EMG signals, especially in electrically noisy environments.

No, these are passive electrodes and cannot be used directly. They require the Olimex SHIELD-EKG-EMG (part #73-0274) or a similar active signal conditioning circuit. The shield provides the necessary high-input-impedance amplification, band-pass filtering, and protection required to safely capture and process the microvolt-level signals from the human body before they can be read by an Arduino's ADC.

This set supports a standard Einthoven Lead I configuration. The Right Arm (RA) and Left Arm (LA) electrodes are the two differential signal inputs, measuring the voltage difference across the chest. The Driven Right Leg (DRL) serves as the reference and noise cancellation point. This setup is ideal for basic heart rate monitoring, rhythm analysis, and educational demonstrations of electrocardiography.