Piezoresistive tactile sensor with tongue pressure measurement capability for dysphagia assessment

Abstract

Diagnosis of dysphagia or difficulty in swallowing begins with suspecting its presence. When dysphagia is suspected, patients with high risks should be screened by means of simplified examinations for dysphagia. Highly sensitive yet simple screening tests are extremely useful when examining patients in both clinical and point-of-care settings. In particular, orthodontists are increasingly interested in analyzing the pressure of the tongue against the hard palate since it gives valuable information on several vital functions, including swallowing and speaking. In this study, we report on the development of a soft and flexible piezoresistive tactile sensor for quantitative measurement of tongue pressure. The sensing layer is made of a grid type MWCNT/PDMS nanocomposite and is attached onto screen-printed interdigitated microelectrodes (IDMs). As the tongue pressure is applied and the sensing layer is deformed, the resistance across the IDMs decreases due to the piezoresistive properties of the nanocomposite. The observed sensor response is highly repeatable and shows an increasing trend as the applied force is varied from 1 to 33 N, which covers the complete required range for measuring human tongue pressure. Furthermore, to ensure practical applicability, the sensor was tested on 30 volunteers to measure their tongue pressure. The obtained sensor output was compared with a commercial pneumatic tongue press device and a high correlation (Pearson's $\mathrm{r}=0.8941829$ ) was obtained. Consequently the proposed tactile sensor shows promise for applicability in measuring tongue pressure.