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Elemyo | 14 February 2020
Sensor MH-BPS101.
Examples of signals.
Examples of signals.
In this article, we showed various forms of EMG and ECG signals obtained when working with the MH-BPS101 sensor, as well as variants of interference arising under various conditions.
Before working with the MH-BPS101 sensor, we strongly recommend you to read detailed instructions.
Before working with the MH-BPS101 sensor, we strongly recommend you to read detailed instructions.
1
An example of an EMG signal from MH-BPS101
2
An example of interference with the MH-BPS101
I. An example of an EMG signal from MH-BPS101.
1. An example of an EMG signal.
The sensor is located along the flexor muscle of the ring finger. The signal was recorded using an AKIP-4107 oscilloscope. When recording a signal, the computer was disconnected from the power supply network and located at a distance at least 0.5 m from household power sources.
Fig. 1: Single, continuous muscle contraction.
Fig. 2: Three consecutive muscle contractions.
2. An example of an ECG signal.
The sensor is located on the left side of the chest along the longitudinal axis of the heart. The signal was recorded using an AKIP-4107 oscilloscope. When recording a signal, the computer is disconnected from the power supply network and is located at a distance of at least 0.5 m from household power sources.
Fig. 3: An example of an ECG signal.
Fig. 4: An example of an ECG signal with one muscle contraction.
3. EMG signal with poor skin contact.
The sensor is located on the calf muscle. Sensor contact with the skin occurs through a thick hairline. The signal was recorded using an AKIP-4107 oscilloscope. When recording a signal, the computer is disconnected from the power supply network and is located at a distance of at least 0.5 m from household power sources.
Fig. 5: Example of an EMG signal in case of poor contact of the sensor with the skin (calf muscle).
The EMG signal is noisy at 50 Hz.
The EMG signal is noisy at 50 Hz.
Fig. 6: EMG signal with a single muscle contraction.
Due to the poor contact of the electrodes with the skin, the electric potentials of the skin and the sensor do not "have time" to equalize, as a result of which there is a strong interference from the household power supply network.
II. An example of interference with the MH-BPS101.
1. The signal when the sensor is connected to a PC disconnected from the power supply.
Fig. 7: EMG signal in the absence of interference 50Hz.
2. The signal when connecting the sensor to a PC connected to the power supply.
Fig. 8: EMG signal is completely noisy at a 50Hz pickup.
The reason is a direct connection to a PC connected to a household network.
The reason is a direct connection to a PC connected to a household network.
3. The signal when connecting the sensor to a PC through galvanic isolation. The PC is connected to the power supply.
Fig. 9: EMG signal is partially noisy with 50Hz interference.
The level of interference depends on the load on the used household network (there is almost no interference at night and day). After 0.5-1 minute after installing the sensor on the body, the interference is significantly reduced.
The level of interference depends on the load on the used household network (there is almost no interference at night and day). After 0.5-1 minute after installing the sensor on the body, the interference is significantly reduced.
4. The signal when connecting the sensor to a PC through galvanic isolation. The power to the PC is turned off, but the power cable is connected to the PC.
Fig. 10: EMG signal does not contain 50Hz interference.
5. Touching the body of wires and devices connected to the power supply network.
Fig. 11: EMG signal contains interference at 50Hz.
Fig. 12: EMG signal with 50 Hz interference.
6. The signal when the sensor is connected to a PC with the power off (the power comes from the battery), but:
a) the power cord is not disconnected from the PC,
b) the power cord is on the side of the PC (for example, it is placed on the same table with the PC).
a) the power cord is not disconnected from the PC,
b) the power cord is on the side of the PC (for example, it is placed on the same table with the PC).
Fig. 13: EMG signal with 50 Hz interference.
7. The output of the signal to a predetermined value with a strong interference of 50 Hz.
Fig. 14: Sensor signal in the first seconds after installation on the body in the presence of strong interference of 50 Hz.
14 FEBRUARY / 2020
Author: Elemyo