High-Precision Wearable Displacement Sensing System for Clinical Diagnosis of Anterior Cruciate Ligament Tears

Abstract

An anterior cruciate ligament (ACL) tear is a common musculoskeletal injury with a high incidence. Traditional diagnosis employs magnetic response imaging (MRI), physical testing, or other clinical examination, which relies on complex and expensive medical instruments, or individual doctoral experience. Herein, we propose a wearable displacement sensing system based on a grating-structured triboelectric stretch sensor to diagnose the ACL injuries. The stretch sensor exhibits a high resolution (0.2 mm) and outstanding robustness (over 1,000,000 continuous operation cycles). This system is employed in clinical trial to diagnose ACL injuries. It measures the displacement difference between the affected leg and the healthy leg during Lachman test. And when such a difference is greater than 3 mm, the ACL is considered to be at risk for injury or tear. Compared with the gold standard of arthroscopy, the consistency rate of this wearable diagnostic system reached about 85.7%, which is higher than that of the Kneelax3 arthrometer (78.6%) with a large volume. This shows that the wearable system possesses the feasibility to supplement and improve existing arthrometers for facile diagnosing ACL injuries. It may take a promising step for wearable healthcare.

Self-Powered Sensing in Wearable Electronics─A Paradigm Shift Technology

“…By combining data sharing and doctors’ guidance, patients achieved over 20–30% enhancement in recovery . Due to the inherent high precision of displacement-sensitive sensors, more sensing devices have been developed. − For instance, Lee reported a bidirectional angular sensor, as shown in Figure d . It is embedded in an arm exoskeleton, serving as an economic and advanced human–machine interface for supporting the manipulation in both real and virtual worlds.…”

“… 116 Due to the inherent high precision of displacement-sensitive sensors, more sensing devices have been developed. 117 − 120 For instance, Lee reported a bidirectional angular sensor, as shown in Figure 10 d. 117 It is embedded in an arm exoskeleton, serving as an economic and advanced human–machine interface for supporting the manipulation in both real and virtual worlds. Figure 10 e presents a stretchable sensor based on a cyclic annular TENG encapsulated in a retractable reel.…”

A heat-triggered triboelectric nanogenerator for self-powered wireless fire alarm

“…To overcome this limitation, researchers have combined gears with springs to create mechanical structures that can harvest and convert irregular low-frequency vibrations or pulsatile surrounding excitations into high-frequency stable alternating current outputs [34,35]. As a typical structural design of TENG, grating-structured freestanding TENGs [36] have been widely sdudied and shown excellent performance in biomechanical and vibrational energy harvesting [37,38] and high precision motion monitoring [39,40]. Welldesigned grating-structured freestanding TENGs [34,35,41,42] is very suitable for this kind of combination with gear systems.…”