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This is the minimum hardware configuration needed for the EMANT380 Bluetooth DAQ to measure the biopotential voltages. The module must be powered from batteries for safety reasons. For the demonstration, we are sampling at 200 samples/sec and reading 400 samples for a duration of 2 seconds. The sampling rate is a multiple of the power line frequency which is 50Hz in our case. When reading waveforms, the EMANT380 resolution is around 30uV. For the first 2 demonstrations, the electrodes are placed on the wrist.
The python program uses the matplotlib module to plot the waveforms and the scipy module for the fft calculations. The top chart shows the raw waveform. The second chart applies a 50Hz notch filter which averages the voltages over 4 samples. The 3rd chart applies a high pass filter using the fft and ifft functions found in the scipy module. This removes the baseline drift. For this first demonstration, you can see clearly the powerline interference and the effectiveness of the notch filter.
One advantage of using the bluetooth module is that it is battery powered and operates at a low and safe voltage. Another advantage is that you can easily move to another location where the power line interference is less as is shown in this demo.
The 3rd demo shows the results when the electrodes are placed on the chest.
This demo shows the results when hand held electrodes are used.
The final demo shows the measurements done on an Android smartphone using py4A which is Python for Android. The charts are created using the flot javascript library. Note that not all the python modules on the PC are available on the android.
The hand held electrodes presents the possibility of novel non-intrusive heart rate monitoring.
We can monitor the heart rates of drivers and cyclists, soldiers and computer gamers without needing for them to put on additional equipment.
Python modules like scipy allows for testing of proof of concept algorithms quickly and inexpensively.