The Diaphragm as Transducer

In a conventional stethoscope, the diaphragm vibration causes air pressure behind the diaphragm to change, which passes up the tubes as a sound wave to impinge pressure changes on the listener's eardrums. Losses occur through the tubing and there is no amplification.

Thinklabs developed a technology that replaces air pressure changes with electric field changes. Having captured diaphragm movement as an electrical signal, it can be amplified and processed with the full power of current technology. The resulting electrical signal is a perfect analog of the air pressure changes at the diaphragm of a traditional stethoscope, ensuring that the electrical signal truly captures the authenticity of stethoscope sound enabling you to use a Thinklabs stethoscope with no "ear re-training".

The Electromagnetic Diaphragm (EmD)

Thinklabs diaphragm technology has been implemented as the Electromagnetic Diaphragm (EmD) used in Thinklabs stethoscopes. The EmD is coated internally with a conductive surface. Spaced behind the diaphragm is a metal plate which is charged to a high voltage, thereby setting up an electric field behind the diaphragm. As the diaphragm moves, the voltage on the plate changes due to changes in the electric field. The beauty of this solution is that the diaphragm moves exactly as it would in a conventional stethoscope, and therefore the vibratory response is identical. The result is a sound familiar to the clinician, but amplified and processed to extract the optimal frequency response.

Patents

Thinklabs has patents for Electromagnetic Diaphragm technology, as well as other technologires related to diaphragm transducers.