Biomechanical Monitoring of Rotator Cuff by an Ultrasensitive Stretchable and Implantable Sensor

Abstract Monitoring of mechanical forces on the rotator cuff in real time after surgical repair may allow the development of personalized rehabilitation programs for patients undergoing recovery. However, there are no currently available modalities for continuous monitoring of the healing process during rehabilitation; previously reported implantable sensors are either too bulky or stiff without sufficient sensitivity. In this study, a strategy employing a stretchable and implantable sensor is proposed for biomechanical monitoring of the rotator cuff. The sensor is made of a patterned boomerang on thin piezoelectric composite sheets, optimized for biosafety, suitability, and functionality. It allows strain and force sensitivities measurements of up to 755 V ε ⁻¹ and 80 V N ⁻¹ , respectively. To the best of the knowledge, the sensor achieves the highest sensitivity among reported flexible piezoelectric strain sensors, although it has the smallest size. In a cadaveric study, the sensor is used to monitor tension changes in the rotator cuff during shoulder movements. In an in vivo study, the sensor exhibits excellent biocompatibility and functionality in a rabbit model. High‐accuracy motion poses recognition is realized using machine learning, illustrating the potential applicability of the device for real‐time monitoring of tendon healing.