Nearly all commercial continuous glucose monitoring (CGM) devices depend on glucose oxidase enzymes that degrade within days to weeks, demanding frequent and costly replacements. Enzyme-free alternatives based on glucose-responsive hydrogels have shown promise, but they remain trapped between two imperfect readout options: optical methods prone to interference and toxicity concerns, and implantation-based ultrasound approaches that require invasive surgery.

In a published in Science Advances, researchers from the Shenzhen Institute of Advanced Technology (SIAT) of the Chinese Academy of Sciences, the Hong Kong Polytechnic University, and the Korea Advanced Institute of Science and Technology, developed the acoustically readable microneedle patch (ARMPatch), a wearable, enzyme-free glucose monitor built entirely from glucose-responsive hydrogel microneedles.

Positioned between a standard ultrasound probe and the skin, the ARMPatch acts as an acoustically augmented interface: as the microneedles absorb interstitial fluid and swell in response to blood glucose fluctuations, the resulting length changes are quantified in real-time by any conventional ultrasound imaging system—no enzymes, no fluorescent dyes, and no custom hardware required.

The ARMPatch sustained stable glucose sensing for 56 days in laboratory tests and enabled seven days of continuous glucose monitoring in freely moving animal models, with ultrasound-measured readings strongly correlated with a commercial glucometer.

Acting as an "accessory" for standard ultrasound probes, the ARMPatch is the first reported approach to continuous glucose monitoring driven by conventional ultrasound imaging, providing a new way for ultrasound in wearable biosensing.

Schematic diagram of a continuous glucose monitoring system using a standard ultrasound probe combined with the developed ARMPatch, and a schematic diagram of the glucose-responsive mechanism of the synthetic hydrogel under glucose regulation. (Image by SIAT)