A Standardized Chewable Conductive Hydrogel Sensor for Direct Monitoring of Masticatory Dynamics.

Abstract

Chewing is a fundamental orofacial function closely related to nutrition, digestion, and quality of life, yet current assessment methods generally rely on indirect signals or endpoint measurements and provide limited process-level information. Here, a hydroxypropyl cellulose (HPC)/polyacrylamide (PAM) conductive hydrogel is developed as a standardized chewable sensor that integrates the test substrate with force-to-electrical signal transduction, enabling direct monitoring of masticatory dynamics. The sensor captures chewing frequency, relative force response, chewing duration, relative force response variability, and rhythm variability during standardized tests. Using predefined chewing-state labels, these features were integrated into a classification framework, with KNN achieving 98.0% accuracy in recording-level cross-validation and 76.7% in nested leave-one-participant-out validation, providing an initial assessment of generalizability to unseen participants. The hydrogel exhibits a compressive strength of 2.3 MPa, toughness of 287 kJ m^{- 3}, a response time of 150 ms, recovery within 173 ms, and less than 3% signal attenuation over 150 cycles. Polydimethylsiloxane (PDMS) encapsulation supports stable intraoral operation and biocompatibility. This work establishes a proof-of-concept platform for standardized acquisition and analysis of process-resolved chewing data, offering a route toward objective, data-driven assessment of masticatory function and, with larger population datasets, personalized oral rehabilitation and healthcare decision-making.