Respiratory belt transducer constructed using a singing greeting card beeper

Abstract

AN ARTICLE by Belušicˇand Zupancˇicˇ(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. 1 Materials needed. The following materials are needed for the construction of the respiratory belt transducer (Fig.

A review of the polygraph: history, methodology and current status

“…This method of measuring respiratory activity is generally considered to have a relatively low frequency response, but this is not thought to be inherently detrimental to polygraph examinations (Baken & Orlikoff, 2000). One available alternative are piezoelectric respiration transducers, which replace the pneumonic rubber bellows with belts that include stretch-sensors, which function based on the property of certain materials, such as crystals, to build up electrical charges (piezoelectricity) when exposed to mechanical stress (Bhaskar, Subramani, & Ojha, 2013). In either case, the acquired measurements of thoracic and abdominal breathing are usually combined (either on paper or by a digitized polygraph) to create a single composite measure of respiration line length for the examiner (Kircher & Raskin, 2002).…”