Electrocardiography is the study of the electrical signals produced by the heart during the cardiac cycle. Doctors monitor a person's electrocardiogram (ECG) in order to assess how the heart is functioning and can be used to diagnose a variety of cardiac diseases. The ECG is thought to have first been discovered by Alexander Muirhead[1] and has become a hallmark in patient care. It turns out that an ECG is very easily obtained with a few common circuit components. I'll show you how to build a 'Super Simply Electrocardiogram (ECG) Circuit.'
This Instructable assumes that you know a few basic concepts of circuit design and analysis such as:
Nodal Analysis
Operational Amplifiers
Filters
If you are a bit shaky on these topics, please consult the links provided for additional information.
Nodal Analysis
Operational Amplifiers
Filters
If you are a bit shaky on these topics, please consult the links provided for additional information.
I am trying to understand the input impedance of this circuit, which is a part of the schematic of this project. Simulate this circuit – Schematic created using CircuitLab. The circuit explanation in the linked page says: 'Note however that the input impedance is 100k resistance between the - input and ground, and 100k between the + input and the - input. Impedance of the electrode. This is important at low frequencies near dc. Instrumentation amplifiers such as the AD8220 and AD8224, shown in Figure 2 and Figure 3, have input bias currents under 20 pA. Biopotential Electrode Sensors in ECG/EEG/EMG Systems.
[1] 'Electrocardiography.' Accessed: November 5, 2016. <https://en.wikipedia.org/wiki/Electrocardiography>
Warning: Please do not connect your ECG circuit to a wall outlet or any instrument powered through the wall outlet for safety reasons.
Warning: This is not a medical device.
Warning: This is not a medical device.