Portable ECG System Design Using the AD8232 Microchip and Open-Source Platform
Miguel E. Bravo-Zanoguera, Daniel Cuevas-González, Juan Pablo Garćıa-Vázquez, Roberto L. Avitia, M. A. Reyna · 2019
This paper presents the design of a portable electrocardiograph (ECG) device using the AD8232 microchip as the analog front-end (AFE). Starting with the manufacturer’s evaluation board of the AFE chip for testing circuit configurations, open-source hardware and software components were integrated into a breadboard prototype. Ultimately, a custom printed circuit board (PCB) was produced. The prototype required to accommodate the microchip on a SMD-to-DIP adapter for testing with the breadboard-friendly Arduino microcontroller alongside a data logger and a Bluetooth breakout board. The analog ECG signal from the AFE output was digitized using one channel of the 10-bit analog-to-digital Converter (ADC) of the ATmega328 microcontroller contained in the Arduino Nano board. The digitized ECG signal can be transmitted not only by serial cable using the Arduino functions, but also via Bluetooth to a PC or to an Android smartphone system when the HC-06 shield is used. The data logging shield provides gigabytes of storage, and the signal is recorded to a micro SD card adapter along with the date and time stamp data of the sample capture (real-time clock provided). In addition to hardware and software development, a simulation was used in the analog circuit design with SPICE Multisim software and the related macromodel library to assess system stability. Besides the analog filters in the AFE stage, digital filtering by means of simple difference equations was investigated. A menu was incorporated to choose from the several modes of operation of the device. The ECG test signals were obtained from a patient simulator (SimCube) and real patients. A portable ECG system for monitoring applications that complies with electrical safety regulations and medical equipment design was realized.