Digital chest expansion measurement & its biomedical application

This paper describes the construction of a device to measure chest expansion. Chest expansion is an important diagnostic criterion. The current methods used are mechanical in nature and lack precision. The objective was to make a device which can measure the chest expansion digitally. Ultrasound sensors have been known to be useful in the measurement of distance. This concept was extended to measuring chest expansion. The subject is made to stand in front of the device and the chest expansion is computed by measuring the distance by means of the ultrasound waves. The device contains an ultrasound transceiver connected to a microcontroller and the results are displayed on a LCD display. The entire unit runs off a 9-volt battery. It is compact and mobile. The device was tested on 30 healthy people with favorable results.