Project Description -
The second project in the course will involve the design of a biopotential signal chain to measure EEG, ECG/EKG and/or EMG signals (your choice) that are present on the surface of the skin. Your regulator from the first project will be used to regulate the supply voltage for the amplifiers and filters in the signal chain. The supply for the A/D converter and microcontroller can be provided by the battery associated with a laptop.
While it is encouraged that you use electrodes connected to the human body with your designed system to make actual biopotential measurements, it is not absolutely required that you do so. If you decide to make actual biopotential measurements, NO system/equipment should be attached/connected to the electrical power grid. Instead, your linear regulator/amplifiers/filters should be powered by a 9V battery and the A/D converter/microcontroller/laptop should be powered by the laptop's internal battery (with the laptop computer itself having been disconnected from the power grid).
At a minimum, you must verify your system's overall behavior by designing/building appropriate test circuits to "emulate" signals that are comparable in amplitude and frequency to the biopotential signals of interest at the surface of the skin, in addition to including:
- 60Hz common-mode noise (with an appropriate amplitude) with electrode impedance imbalance effects to investigate your system's ability towards rejecting common-mode noise (i.e. common-mode rejection ratio, CMRR), and
- Electrode DC offset imbalance to investigate your system's ability towards rejecting "large" input DC/low-frequency differential signals
In order to gauge the effectiveness of your system, the A/D converted signals should be analyzed both in the time- and frequency-domains in MATLAB (or another comparable program) to see whether the desired biopotential signal(s) can still be detected in spite of the above bullet points that are present in the "real world."
As possible starting points for the above bullet points, you may find the following references useful:
- Figure 6 of the posted "AC-coupled front-end for biopotential measurements" research paper
- The "signal composition" section on Page 3 of the posted "Getting the most out of your in-amp design" application note
Furthermore, reference laboratory documents from other universities have been posted to serve as starting points towards designing/building appropriate biopotential signal chain systems, in addition to building test circuits to "emulate" biopotential signals.
In addition to the Analog Devices OP90 opamps, you may obtain from the instructor an Analog Devices AD620 instrumentation amplifier chip to use in your signal chain. Furthermore, you may obtain from the instructor BIOPAC EL503 electrodes if you are interested in using your designed system to make actual biopotential measurements.
In addition to having a functional signal chain, the goal of your project is to have made design decisions/efforts aimed at improving specs/parameters often used to gauge the effectiveness of a biopotential measurement system.
Design Project Report - Must follow the following format:
- Title/Cover Page
- Objectives/Application
- Circuit Schematic/Description
- Analysis Calculations
- Simulations
- Experiments
- Discussion
Attachment:- Assignment Files.rar