Portable 6 Lead 4 Electrode EKG

This project focused on designing a small, portable, 6 lead 4 electrode electrocardiogram (EKG) machine with enough accuracy and resolution to successfully diagnose clinical issues. The electrical design used to measure signals originating from the heart can be broken up into three stages. The first stage is the human device interface. Next, is the analog block that filters out common mode noise and conditions the signal for digital encoding using instrumentation amplifiers, a right leg circuit, high pass, low pass, and an amplifier. This circuit filters all frequencies above and below the frequency band of meaningful data (1-160Hz), rejects signals common to all of the electrodes, and amplifies signals to a value measurable by the digital ADC. After the three data signals have gone through the analog block they are passed to the digital block. Here the data is digitized using an analog converter, formatted to be sent in a useful way to an external device. This device can save or display the information in real time. This is done by using a serial USB connection to a computer, and then presenting that data using a GUI built in C#. A microcontroller with an on-board ADC was used to digitize, format, and transmit the data. The graphical user interface on a computer was used to simultaneously save the data in a text file and plot that data on a graph for easy analyzing. The final analog design function at the bread board level, but critical mistakes were made when designing the printed circuit board. The microcontroller and user interface on the computer worked with marginal success. This project provided an important first step in the development of a viable product