technological measuring devices attached to an animal, person, or plant in order to record biological processes.
Modern biological sensors convert the biophysical or biochemical quantity being investigated into some sort of electrical signals. Biological sensors that record physiological factors are called physiological sensors. Biological sensors are used in biotelemetry for the remote observation of animal behavior under natural or near-natural conditions (for example, in studying migrations of fish or birds), in ecological research, in studying the body state of aviators and astronauts, in the physiology of work and athletics, and in clinical practice. Some biological sensors are applied to the body surface (for example, thermocouples for measuring skin temperature, electrodes in electroencephalography and electrocardiography, and sensors attached to an animal to record its movements in an experimental chamber or open-air cage). Other sensors are inserted inside the body: they are implanted (for example, electrodes in the brain), introduced by means of a probe, or introduced in the form of so-called radiocapsules into the cavities of the stomach, heart, or other organs. Biological sensors are classified according to the factor recorded (movement, growth, respiration, cardiac activity), the type of contact with the body, and the principle of operation.