Functional, RF‐Trilayer Sensors for Tooth‐Mounted, Wireless Monitoring of the Oral Cavity and Food Consumption

TLDR

Wearable devices are powerful for personalized healthcare, yet challenges limit their use as continuous physiological monitors, and the proposed format could be extended to diverse interlayer materials for added sensing specificity. The study develops a materials‑based strategy to enhance traditional dielectric sensors by creating a conformal RF construct with an active layer between two reverse‑facing split ring resonators. The authors fabricate small passive dielectric sensors (down to 2 mm × 2 mm) with enhanced sensitivity, using an active interlayer encapsulated between two reverse‑facing split ring resonators, which can be further functionalized. Demonstrator devices using a porous silk film or a pH/temperature‑responsive PNIPAM hydrogel were successfully adhered to tooth enamel, enabling in vivo detection of foods and providing multiplexed, data‑rich temporal information on analyte diffusion.

Abstract

Abstract Wearable devices have emerged as powerful tools for personalized healthcare in spite of some challenges that limit their widespread applicability as continuous monitors of physiological information. Here, a materials‐based strategy to add utility to traditional dielectric sensors by developing a conformal radiofrequency (RF) construct composed of an active layer encapsulated between two reverse‐facing split ring resonators is applied. These small (down to 2 mm × 2 mm) passive dielectric sensors possess enhanced sensitivity and can be further augmented by functionalization of this interlayer material. Demonstrator devices are shown where the interlayer is: (i) a porous silk film, and (ii) a modified PNIPAM hydrogel that swells with pH or temperature. In vivo use is demonstrated by adhesion of the device on tooth enamel to detect foods during human ingestion. Such sensors can be easily multiplexed and yield data‐rich temporal information during the diffusion of analytes within the trilayer structure. This format could be extended to a suite of interlayer materials for sensing devices of added use and specificity.