Electromagnetic Diaphragm
Encyclopedia
Electromagnetic Diaphragm is a form of capacitive sensor used on an electronic stethoscope. The diaphragm is coated with a conductive material. Behind the diaphragm, a conductive plate is positioned behind and parallel to the diaphragm, so that the two conductive elements form a capacitor
. Capacitance is a function of plate area, dielectric properties of the space between the conductors, and the distance between the conductors. It is this latter parameter which is modulated by vibration
such that the capacitance varies with the distance between the electromagnetic
diaphragm and the plate, forming an acoustic sensor.
The electromagnetic diaphragm is a form of capacitive sensor, and shares properties with condenser microphones. The difference between the electromagnetic diaphragm and a condenser microphone is that a condenser microphone operates on the basis of air transmission, has a very thin membrane instead of a diaphragm, and cannot be placed against a body to sense sounds within the body.
The electromagnetic diaphragm for stethoscopes was patented by Clive Smith in 2002 and is used on Thinklabs
electronic stethoscopes.
Capacitor
A capacitor is a passive two-terminal electrical component used to store energy in an electric field. The forms of practical capacitors vary widely, but all contain at least two electrical conductors separated by a dielectric ; for example, one common construction consists of metal foils separated...
. Capacitance is a function of plate area, dielectric properties of the space between the conductors, and the distance between the conductors. It is this latter parameter which is modulated by vibration
Vibration
Vibration refers to mechanical oscillations about an equilibrium point. The oscillations may be periodic such as the motion of a pendulum or random such as the movement of a tire on a gravel road.Vibration is occasionally "desirable"...
such that the capacitance varies with the distance between the electromagnetic
Electromagnetic
Electromagnetic may refer to:* Electromagnetism* Electromagnetic field* Electromagnetic force* Electromagnetic radiation* Electromagnetic induction* Electromagnetic spectrum...
diaphragm and the plate, forming an acoustic sensor.
The electromagnetic diaphragm is a form of capacitive sensor, and shares properties with condenser microphones. The difference between the electromagnetic diaphragm and a condenser microphone is that a condenser microphone operates on the basis of air transmission, has a very thin membrane instead of a diaphragm, and cannot be placed against a body to sense sounds within the body.
The electromagnetic diaphragm for stethoscopes was patented by Clive Smith in 2002 and is used on Thinklabs
Thinklabs
Thinklabs Technosolutions Pvt Ltd, styled ThinkLABS, is an Indian venture in the field of educational robotics and embedded systems, founded in November 2005. ThinkLABS is currently incubated at the Indian Institute of Technology Bombay...
electronic stethoscopes.