The term Biosignal refers to all the signals generated in the human body or any other living organism. More specifically, it represents all those signals from living organisms that are monitored to obtain certain usage information. Primarily, the term refers to electrical signals in nature, but some non-electric signals are monitored.
Typically, the changes in potential difference across a certain tissue in the body are measured in the case of bio-electric signals. Let us have a look at a few of the properties of biosignals generated by the human body that are analyzed to obtain information:
In the case of Electroencephalography, the activity of the human brain is monitored. Usually, at a synapse (junctions between the nervous system cells), the flow of ions occurs. This results in the formation of various signals that are used by the body to transfer information. The voltage variations caused by these signals are recorded, and thus, the brain’s activity is measured.
In Magnetoencephalography, the magnetic fields produced by the variations of electric currents that form the brain activity are monitored. For this, devices such as SQUID (Superconducting Quantum Interface Devices) are used to have high sensitivity. Many difficulties are faced one tries to measure the same as the ambient magnetic noise in urban areas is quite high. Even with SQUID, about 50 thousand neurons need to be active at a given moment to measure the field.
The galvanic Skin Response
The galvanic Skin Response technique is used to measure the electric resistance offered by the skin. In it first, a random area of the skin is selected to measure establish the base resistance, and then, the area in concern is studied about the data that has already been obtained. As emotional arousal increases skin activity, it is generally used in polygraph tests.
The Electrocardiograph is produced by recording the electrical waves that are produced by a person’s heart. The human heart produces these waves when it pumps blood into the human body. These waves are measured by electrodes that are attached to the person’s skin. The rhythms produced by these heartbeats are analyzed to detect weaknesses in the heart muscles or some other abnormalities.
Electromyography is similar to Electrocardiography but is used for any muscles in the body and not the heart muscles in particular. Similar to the heart muscles, the muscles in other parts of the body also produce electric waves when they contract. Their abnormal activity can be detected by the fluctuations in the graph that are recorded.
Thus, the body’s various signals prove to be very useful in detecting any abnormalities present in the body. Biosignal processing is also used in research to understand various activities performed by specific organs in one’s body.