Engineer Israa Issa Ibrahim The process of converting bioactivity within heart cells into digital electrical signals is considered one of the most fascinating applications of electrical engineering in medicine. This field is called “Biomedical Signal Processing”, which explains how we can translate the chemical language of cells into the language of smart devices. Here is an article explaining this technical pathway: From the Pulse to Data: The Journey of the Heart’s Electrical Signal 1. Origin: Converting Chemical Energy into Electrical Potential The journey begins inside the heart cells, specifically in the sinoatrial (SA) node. Here, cells do not use wires; they use ions: Ion Pumps: Cells exchange sodium ions ( 𝑁 𝑎 + Na + ) and potassium ions ( 𝐾 + K + ) across their membranes. Action Potential: This exchange creates a momentary voltage difference called the action potential. This voltage is the “spark” that travels from one cell to another, triggering heart contraction. 2. Capture: The Role of Electrodes as Energy Transducers As these electrical waves spread through body fluids, they reach the skin. Here, the electrical engineer’s role comes into play in designing electrodes: Electrochemical Interface: The electrode (usually 𝐴 𝑔 / 𝐴 𝑔 𝐶 𝑙 Ag/AgCl) acts as a transducer, converting the ionic current in the body into an electronic current that flows through copper wires. Challenge: The captured signal is very weak (about 1–2 millivolts) and is immersed in electromagnetic noise from surrounding devices. 3. Conditioning: Signal Filtering and Amplification (Analog Conditioning) Before a computer can understand the signal, it must be physically processed using analog circuits: Amplification: Instrumentation amplifiers boost the signal voltage thousands of times without distortion. Filtering: Band-pass filters remove frequencies caused by muscle movement or household electrical interference (50/60 Hz). 4. Digitization: Analog-to-Digital Conversion (ADC) This is the critical stage where the continuous waveform becomes data: Sampling: Thousands of signal snapshots are taken per second. Quantization: Each voltage snapshot is converted into a binary code (0s and 1s). Higher bit resolution means more accurate representation of the heartbeat and its fine details. 5. Analysis: Data Processing and Interpretation Once the signal is digital, it enters microprocessors, where it can be used for: Heart Rate Calculation: Algorithms detect the R-peak of the waveform. Smart Diagnosis: Artificial intelligence compares the recorded signal with known heart disease patterns. Al-Mustaqbal University — the first university in Iraq.