Going Bio: ECG Amplifier

Circuit connected to Arduino and batteries

The finished product!

This semester, my project work portfolio took a turn for the biomedical with an ECG data acquisition build!

This was a partnered project, and the process of designing, building and presenting required a generous amount of planning and time management.

The Idea

Traditional portable ECGs, such as Holter Monitors used for diagnostic purposes are bulky, expensive and intrusive.

Their consumer alternatives, such as the FitBit and Apple Watch, do not provide in-depth information on the function of the heart, and cannot detect potentially lethal conditions such as atrial fibrillation.

However, commonly found DIY ECG circuits often neglect to address electrical safety concerns and present a potential risk of electrical shock.

In light of these concerns, our team aimed to create an accessible and safe middle ground between a high-end Holter monitor and consumer grade heart rate monitors, by creating a portable ECG 3 lead system that made use of the popular Arduino development platform for data acquisition in MATLAB.

Design and Build

Design sketches on paper

Initial design sketches

ECG circuit on breadboard.

The completed breadboard build during the early testing phase.

 

 

 

 

 

 

 

 

 

 

First came the rough design sketches pictured above, where we started with a system overview and then delved into the nitty-gritty of using the supplied components: an instrumentation amplifier, a selection of op-amps and ECG leads. Then, the breadboard allowed us to test and adjust our design as required.

ECG signal on oscilloscope.

Finally! The ECG signal needed refinement, but showed the R peaks clearly.

Early testing phase, featuring a very noisy signal!

 

 

 

 

 

 

 

 

 

 

 

As shown in the first photo, we later transferred our finished and refined design to a stripboard for demonstration and better stability, as well as adding a DC source before the initial testing phase to protect the test subjects.

I was delighted to have the chance to work on this extremely rewarding project, and hopefully for the chance at more bio-related projects in the future!

 



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