Biosignal is a summarizing term for all kinds of signals that can be (continually) measured and monitored from biological beings. The term biosignal is often used to mean bio-electrical signal but in fact, biosignal refers to both electrical and non-electrical signals.

Electrical biosignals ("bio-electrical" signals) are usually taken to be (changes in) electric current

Electric current

Electric current is a flow of electric charge through a medium.This charge is typically carried by moving electrons in a conductor such as wire...

s produced by the sum of electrical potential differences across a specialized tissue, organ or cell system like the nervous system

Nervous system

The nervous system is an organ system containing a network of specialized cells called neurons that coordinate the actions of an animal and transmit signals between different parts of its body. In most animals the nervous system consists of two parts, central and peripheral. The central nervous...

. Thus, among the best-known bio-electrical signals are the

• Electroencephalogram (EEG)
• Magnetoencephalogram (MEG)
• Galvanic skin response
  Galvanic skin response
  Skin conductance, also known as galvanic skin response , electrodermal response , psychogalvanic reflex , skin conductance response or skin conductance level , is a method of measuring the electrical conductance of the skin, which varies with its moisture level...
  
   (GSR)
• Electrocardiogram
  Electrocardiogram
  Electrocardiography is a transthoracic interpretation of the electrical activity of the heart over a period of time, as detected by electrodes attached to the outer surface of the skin and recorded by a device external to the body...
  
   (ECG)
• Electromyogram (EMG)
• Heart Rate Variability
  Heart rate variability
  Heart rate variability is a physiological phenomenon where the time interval between heart beats varies. It is measured by the variation in the beat-to-beat interval....
  
   (HRV)

Electrical currents and changes in electrical resistance

Electrical resistance

The electrical resistance of an electrical element is the opposition to the passage of an electric current through that element; the inverse quantity is electrical conductance, the ease at which an electric current passes. Electrical resistance shares some conceptual parallels with the mechanical...

s across tissues can also be measured from plants.

Bio-signals may also refer to any non-electrical signal that is capable of being monitored from biological beings, such as mechanical signals (e.g. the mechanomyogram or MMG), acoustic signals (e.g. phonetic and non-phonetic utterances, breathing), chemical signals (e.g. pH, oxygenation) and optical signals (e.g. movements).

Applications

• Using electroencephalograph signals for task classification and activity recognition Microsoft
• [ftp://ftp.hq.nasa.gov/pub/pao/pressrel/2001/01-012.txt NASA scientists use hands-off approach to land passengers jet]

Hardware

University project

• University of Vienna : cours Biomedical Engineering, Electromyography (EMG)
• Electroencephalographe,EEG, sans fil ( Cornell University, Ithaca, NY, USA)

See also

• Bioindicator
  Bioindicator
  Biological indicators are species used to monitor the health of an environment or ecosystem. They are any biological species or group of species whose function, population, or status can be used to determine ecosystem or environmental integrity. An example of such a group are the copepods and other...
  
  
• Biomarker
• Biosignature
  Biosignature
  A biosignature is any substance -such as an element, isotope, or molecule - or phenomenon that provides scientific evidence of past or present life. Measurable attributes of life include its complex physical and chemical structures and also its utilization of free energy and the production of...
  
  
• Molecular marker
• Multimedia Information Retrieval
  Multimedia Information Retrieval
  Multimedia Information Retrieval is a research discipline of computer science that aims at extracting semantic information from multimedia data sources. Data sources include directly perceivable media such as audio, image and video, indirectly perceivable sources such as text, biosignals as well...