Injectable ultrasonic metagels for intracranial monitoring

Abstract Annually, over 10 million patients undergo high-risk invasive intracranial monitoring, facing risks of infection and secondary surgeries. Injectable ultrasonic metagels, wireless, biodegradable sensors with air-column matrices for multiparameter (pressure, temperature, pH, flow) ultrasound readout, are delivered via 5.8 mm burr-hole/22 G needle (avoiding ≥10 mm craniotomy), enabling ambulatory monitoring. Biodegradation eliminates removal surgery, addressing biocompatibility, fidelity, and deployability. However, unresolved degradation kinetics, motion artifact, and deep-tissue signal require resolution for further clinical translation.