During the academic year of 2016-2017 at McMaster University, in conjunction with Dr. DeBruin, Christina Riczu, Thomas Phan and Emilie Corcoran, we developed a compact, battery powered, 12-lead electro-cardiogram. The project won 1st place in the biomedical category at the ECE Capstone Poster Day.
The final report we handed in for the course is attached at the end of this post and includes background information, a design overview, schematics and bill of materials for the hardware we developed. This post will introduce the project and serve as a personal account of the considerations and problems associated with the portion of the project that I focused on.
Before we begin I should note that if you decide to replicate this design or develop a derived design that you are doing so at your own risk. Attaching a device with a low impedance connection to a person can be dangerous. We developed this project under a supervisor with experience developing and maintaining such devices and protocols were put into place to ensure safety.
My goal during the project was to develop the most compact device possible while providing robust mechanical design, usable battery life, convenient connectivity, a clean user interface, and good analog performance. For this to occur components must be selected carefully across electrical, mechanical and software domains. In addition to this I wanted the design to be reusable and extendable in the future, choices were made to allow the circuit boards to be used for different applications beyond this project.
The purpose of the hardware is to perform signal conditioning, analog to digital conversion and transfer the data to a host.
The software processes the data and displays it in a graphical interface.
Low cost cables for connecting skin electrodes to a data acquisition system is available on EBay. If you search for Contec ECG cable on EBay you will find them for about $20. They interface with a DB15 connector and come terminated with button snap connectors for connecting with commonly available ECG electrodes such as the 3M Red Dot silver-silver chloride electrodes.