Respiratory belt transducer constructed using a singing greeting card beeper.

AN ARTICLE by Belušič and Zupančič (1) described the construction of a finger pulse sensor using a singing greeting card beeper. We felt that this beeper made of piezoelectric material could be easily modified to function as a respiratory belt transducer to monitor respiratory movements. Commercially available respiratory belt transducers, such as Pneumotrace (http:// www.adinstruments.com/products/mlt1132; marketed by AD Instruments), also use such piezoelectric material. After modification, the beeper was attached to the chest using Velcro straps. The strain induced on the piezoelectric material of the beeper by the chest movement produces a corresponding voltage change, which can be recorded by a computer using data-acquisition systems or observed using an oscilloscope. The construction of the respiratory belt transducer is described below. Materials needed. The following materials are needed for the construction of the respiratory belt transducer (Fig. 1):