Self-Powered Load Sensors for Total Knee Replacement Health Monitoring

本研究的目的是制作一套全膝关节自力式负载传感系统的样机 全膝关节置换术(TKR)及其在模拟身体膝关节上的临床前试验 日常生活活动。TKR是最常见的手术，由于 骨关节炎在老年人中流行，运动事故在年轻人中流行。在关节置换期间 手术、假体对准以提供适当的运动学和稳定性。不幸的是，异常负荷 植入物错位或术后韧带失衡导致的模式可导致早期失败。 如果没有定量的关节负荷数据，很难跟踪植入物的长期健康状况。这一点尤其正确 对于远程医疗，由于对亲自就诊的限制，远程医疗已变得越来越普遍 新冠肺炎大流行的影响。使用嵌入式自主传感器非侵入性测量负载的能力 将有助于更早地识别异常负荷并制定治疗策略。 最先进的技术使用电磁或压电换能器。电磁设备需要 假体内装有线圈和磁铁，这可能会削弱假体的结构。压电体 另一方面，传感器通常是由含有铅的陶瓷制成的，这些铅对人体健康有明显的影响。 风险。无铅压电材料已经问世，但它们的功率密度较低，特别是 与较新的能源收集技术相比。摩擦电能采集是一种新发现的能源。 基于接触带电和静电感应的收获技术。摩擦电动能量采集器 通过在带有微图案纹理的接触表面产生电荷，将循环运动转化为电能。这个 广泛的材料表现出摩擦电学特性，允许在低成本的收割机设计中的灵活性 成本、高灵敏度、高功率密度和生物兼容性，使其成为植入物应用的理想选择。 为了利用这一前景看好的新技术，我们提出了一种自供电负载监测系统，用于 TKR可定制安装在超高相对分子质量聚乙烯(UHMWPE)之间 轴承和胫骨托盘，允许将该设备整合到任何TKR系统中。负荷监测 该系统包括四台收割机，在胫骨托盘的每个象限内一台，以及一个前端电子系统。这个 系统可以在一段时间内监控四个象限的力分布。这些信息对健康是必不可少的 监测种植体，因为异常的负荷传递是种植体翻修手术的主要原因。 采集到的能量很少(约20微瓦)，但足以提取出 一整天的负荷。数据将在计算机上收集，正常加载与异常加载 模式将使用人工神经网络进行分类。这种创造性的方法使传感器能够 仅使用收割机产生的动力连续运行。拟议中的项目可以带来革命性的变化 通过提供可指导卫生保健决策的量化数据，可以在生物医学植入领域提供数据。

The goal of this research is to make a prototype of a self-powered load sensing system for Total Knee Replacement (TKR) and show its effectiveness via pre-clinical testing on cadaver knees under simulated activities of daily living. TKR is the most common surgery, and it is growing in numbers because of the osteoarthritis epidemic in older people and sports accidents in younger people. During joint replacement surgeries, prosthesis are aligned to provide appropriate kinematics and stability. Unfortunately, aberrant loading patterns resulting from implant misalignment or ligament imbalance after surgery can result in early failure. Tracking the long-term health of the implant is difficult without quantitative joint load data. This is especially true for telehealth, which have become increasingly common due to restrictions on in-person clinic visits as a result of the COVID-19 pandemic. The ability to noninvasively measure loads using embedded autonomous sensors would enable earlier identification of aberrant loading and the development of treatment strategies. State-of-the-art technologies use electromagnetic or piezoelectric transducers. Electromagnetic devices require incorporation of a coil and magnets within the prosthesis, which may weaken the structure. Piezoelectric transducers, on the other hand, are most commonly made of ceramics that contain lead posing obvious health risks. Lead-free Piezoelectric materials have been made, but they have lower power density, especially compared to newer energy harvesting technology. Triboelectric energy harvesting is a newly discovered energy harvesting technique based on contact electrification and electrostatic induction. Triboelectric energy harvesters convert cyclic motion to electricity by generating charges at micro-patterned textured contacting surfaces. The wide range of materials that exhibit triboelectric properties allows flexibility in the design of harvesters for low cost, high sensitivity, high power density and biocompatibility, making them ideal for implant applications. To take advantage of this promising new technology, we propose a self-powered load monitoring system for TKR that can be customized and installed between the ultra-high molecular weight polyethylene (UHMWPE) bearing and the tibial tray, allowing the device to be incorporated into any TKR system. The load monitoring system comprises four harvesters, one in each quadrant of the tibial tray, and a frontend electronics system. The system can monitor the force distribution across four quadrants over time. This information is essential in health monitoring of the implant because aberrant load transmission is a leading cause of implant revision surgeries. The amount of energy harvested is small (~20 microwatts), but is adequate for extracting important features of the load throughout the day. The data will be gathered on a computer and normal versus abnormal loading patterns will be classified using artificial neural networks. This creative approach enables the sensor to continuously operate using solely the power produced by the harvester. The proposed project can revolutionize the biomedical implant field by providing quantitative data that can guide health care decision making.