Biosignal
A biosignal is any signal in a living organism that can be continually measured and monitored. The term biosignal is often used to refer to bioelectrical signals, but it may refer to both electrical and non-electrical signals. The usual understanding is to refer only to time-varying signals, although spatial parameter variations are sometimes subsumed as well.
Electrical biosignals
Electrical biosignals, or bioelectrical time signals, usually refers to the change in electric current produced by the sum of an electrical potential difference across a specialized tissue, organ or cell system like the nervous system. Thus, among the best-known bioelectrical signals are:- Electroencephalogram
- Electrocardiogram
- Electromyogram
- Electrooculogram
- Electroretinogram
- Electrogastrogram
- Galvanic skin response or electrodermal activity
With the development of methods for remote measurement of electric fields using new sensor technology, electric biosignals such as EEG and ECG can be measured without electric contact with the skin. This can be applied, for example, for remote monitoring of brain waves and heart beat of patients who must not be touched, in particular patients with serious burns.
Electrical currents and changes in electrical resistances across tissues can also be measured from plants.
Biosignals may also refer to any non-electrical signal that is capable of being monitored from biological beings, such as mechanical signals, acoustic signals, chemical signals and optical signals.