Wireless, wearable elastography via mechano-acoustic wave sensing for ambulatory monitoring of tissue stiffness.

Assessing the mechanical properties of soft tissues holds broad clinical relevance. Advances in flexible electronics offer possibilities for wearable monitoring of tissue stiffness. However, existing technologies often rely on tethered setups or require frequent calibration, restricting their use in ambulatory environments. This study introduces a mechano-acoustic wave sensing technology for automated, wireless elastography. The patch-form sensor maintains conformal contact with the skin, regardless of body motion or deformation. It provides continuous, depth-sensitive estimation of subcutaneous tissue stiffness through real-time surface wave dispersion analysis. Theoretical and experimental investigations on phantom materials and tissues spanning a wide range of Young's modulus (in kilopascals to megapascals) demonstrate the capability of the device to rapidly and robustly evaluate the stiffness at depths up to several centimeters. The device shows compatibility with various tissue models, with results consistent with in-parallel ultrasound elastography measurements. Deployment of the device during exercises confirms its viability for ambulatory monitoring, enabling continuous assessment of variation in tissue stiffness.