Physiological instruments

thumb|American inventor Leonarde Keeler testing his improved polygraph on [[Arthur Koehler, a former witness for the prosecution at the 1935 trial of Richard Hauptmann]] A polygraph, often incorrectly referred to as a lie detector test, is a pseudoscientific device or procedure that measures and records several physiological indicators such as blood pressure, pulse, respiration, and skin conductivity while a person is asked and answers a series of questions. The belief underpinning the use of the polygraph is that deceptive answers will produce physiological responses that can be differentiate

A sphygmomanometer ( ), also known as a blood pressure monitor, blood pressure machine, or blood pressure gauge, is a device used to measure blood pressure, composed of an inflatable cuff to collapse and then release the artery under the cuff in a controlled manner, and a mercury or aneroid manometer to measure the pressure. Manual sphygmomanometers are used with a stethoscope when using the auscultatory technique.

medical device for determining the concentration of glucose in the blood

personal monitoring device

300px|thumb|A sphygmograph, probably of Etienne-Jules Marey's design The sphygmograph ( ) was a mechanical device used to measure blood pressure in the mid-19th century. It was developed in 1854 by German physiologist Karl von Vierordt (1818–1884). It is considered the first external, non-intrusive device used to estimate blood pressure.

A hemoglobinometer or haemoglobinometer (British English) is a medical device used to measure hemoglobin concentration in blood. It can operate by spectrophotometric measurement of hemoglobin concentration. Portable hemoglobinometers provide easy and convenient measurement of hematological variables, especially in areas where clinic laboratories are unavailable.

A phonometer is an instrument invented by Thomas Edison for testing the force of the human voice in speaking. It consists chiefly of a mouthpiece and diaphragm. Behind the diaphragm is placed a delicate mechanism which operates a 15-inch flywheel by means of which a hole can be bored in an ordinary pine board.