Injectable Bioadhesive Ultrasonic Sensor for Continuous and Wireless On-Demand Pressure Monitoring in Acute Compartment Syndrome.

Acute compartment syndrome (ACS) is a severe orthopedic emergency caused by limb injuries and elevated intra-compartmental pressure (ICP), which can lead to permanent disability. Clinical practice has long pursued continuous and on-demand ICP monitoring across the risk window for accurate ACS management. Existing probe manometry imposes pain and infection risk, particularly during prolonged wired indwelling or repeated punctures. Implantable electronic sensors enable wireless monitoring, but face biocompatibility and stability challenges from the mismatched human-machine interface. Here, we present an injectable, bioadhesive ultrasonic sensor (metagel sensor) that enables continuous and wireless on-demand monitoring of intracompartmental pressure across the post-njury clinical window. The ultrasonic modulation properties of the metastructural hydrogel encode pressure signals into reflected ultrasonic waves as measurable bandgap shifts, enabling fully passive wireless readout. The metagel exhibited substantial biodegradation over 14 weeks in rats. In a porcine model, we demonstrated the capability of the metagel sensor in continuous acute-phase ICP monitoring and repeated wireless on-demand interrogation over 10 days. Simultaneously decoupled signals related to respiration and pulse offer additional physiological information relevant to ACS assessment.