Electronics-free, wearable ultrasonic tags for on-demand health monitoring in epidermal and ocular applications

Abstract

Medical ultrasound is widely used, but the size, complexity, and need for trained operators currently restrict its use to clinical settings, limiting opportunities for remote patient monitoring. Despite the rapid emergence of wearable ultrasound in the research community, the common practice still requires wired connections to benchtop instruments. While a few fully wearable and integrated solutions do exist, complex ultrasound electronics are bulky and power hungry, impeding unobtrusive sensing and seamless integration into daily lives. Here, we report miniaturized ultrasonic (US) tags in epidermal patch and contact lens formats that are electronics free, enabling comfortable, on-demand, and operator-free US measurements, including bladder volume, axial eye length, muscle activity, and blood pressure. US transducers are coupled with millimeter-sized antennas to enable on-demand, wireless measurements when in proximity to an external coil. We demonstrate the versatility of the US tags through in vitro, ex vivo, and pilot in vivo experiments.