Pneumograph

From Ask Dr Wiki

A pneumograph, also known as a pneumatograph or spirograph, is a device for recording velocity and force of chest movements during respiration.

Principle of operation

There are various kinds of pneumographic devices, which have different principles of operation. In one mechanism, a flexible rubber vessel is attached to the chest. The vessel is equipped with sensors. Others are impedance based, and thus the form of sensor is something that measures electrical conductivity.