Wearable ultrasonic sensor technology for biomedical monitoring

对于老年人来说，一个特别而重要的问题是，一旦他们经历了身体上的障碍，他们经常被放在床上休息。这需要护理人员的特殊和强烈的护理来维持他们的日常活动。此外，肌肉骨骼疾病会损害病人的身体能力。这些疾病的早期诊断对于适当治疗至关重要，以防止疾病的进一步发展。此外，生物组织的力学性能，如刚度和粘度，会因疾病、老化、损伤和疲劳而发生变化。因此，这些属性包含了医学诊断的重要和有用的信息。x射线和MRI能够为医学诊断提供高空间分辨率的解剖图像。然而，它们相当昂贵，而且只能在诊所或医院买到。**超声已成为医学诊断的有力工具，由于其无创，无风险（无电离辐射暴露），并且能够以高帧率和低成本实时捕获图像而被广泛使用。超声诊断技术不仅可以提供解剖结构的静态图像，还可以提供与身体和生理活动相关的内部组织运动的实时动态信息。除了常规的定性图像外，如果能够定量地获得组织内部运动和力学特性，这种增强的信息将极大地帮助医生做出快速、准确和适当的诊断。此外，如果可以在临床设施和实验室之外进行实时和连续的超声监测和诊断，而不限制日常生活活动，这是有益的。目前用于监测身体活动（如肌肉收缩）的非侵入性、可穿戴和/或非接触式技术包括肌力图、表面肌电图和3D运动捕捉。然而，这些技术在组织深度方向上缺乏灵敏度/空间分辨率，或者只能监测体表的外部运动，而不能监测内部组织的详细运动。因此，评估位于身体深处的单个肌肉可能是困难或不可能的。**本研究计划的目标是开发一种可穿戴超声波传感器和相关的信号处理算法，可以在身体活动期间持续实时监测内部组织运动。这种传感器的特点是：轻便、灵活、可批量生产、低成本，因此是一次性的。对于接触人体的医疗设备来说，传感器的一次性是可取的，因为它在使用后不需要消毒或灭菌。在本研究计划中开发的可穿戴超声波传感器技术能够定量测量感兴趣组织的机械行为和性能。开发的技术将能够在医院、诊所和实验室之外监测受试者的身体状况。此外，人们将能够佩戴具有成本效益的超声波传感器，持续监测他们的健康状况。该开发技术的应用不仅在医学诊断和健康监测领域，而且在康复、运动机能学和运动中进行有效和高效的身体训练。科学、工程和临床研究人员可以从这种新的超声波传感技术中受益，通过监测各种身体活动中他们感兴趣的组织运动来研究和理解人体生理学。

One of the particular and significant issues for elderly people is that once they experience a physical disorder, they are often placed on bed rest. This requires special and intense care from caregivers to maintain their daily activities. Also, musculoskeletal diseases impair a patient's physical ability. Early diagnosis of such ailments is crucial for appropriate treatment in order to prevent further progression of the disease. In addition, mechanical properties of biological tissues, such as stiffness and viscosity, change due to the disease, aging, injury and fatigue. Thus, such properties contain significant and useful information for medical diagnosis. X-ray and MRI are capable of providing anatomical images with high spatial resolution for medical diagnosis. However, they are rather expensive and available only in clinics or hospitals. **Ultrasound has been a powerful tool for medical diagnosis and is widely used since it is noninvasive, risk-free (no ionizing radiation exposure), and capable of capturing images in real-time at a high frame rate and at low-cost. Ultrasonic diagnostic techniques can provide not only static images of anatomical structures but also real-time dynamic information of internal tissue motion associated with physical and physiological activities. If one can obtain internal tissue motion and mechanical properties quantitatively, in addition to conventional qualitative images, such augmented information would greatly aid doctors in making fast, accurate, and appropriate diagnoses. In addition, it is beneficial if real-time and continuous ultrasonic monitoring and diagnosis could be performed outside of clinical facilities and laboratories, without restricting daily life activities. Current non-invasive, wearable and/or non-contact techniques employed for monitoring physical activities, such as muscle contractions, include mechanomyography, surface electromyography, and 3D motion capture. However, these techniques lack sensitivity/spatial resolution in the tissue depth direction, or are capable of only monitoring the external motion at the body surface but not the detailed motion of internal tissues. Therefore, it might be difficult or impossible to assess the individual muscle located deep in the body.**The objective of this proposed research program is to develop a wearable ultrasonic sensor and associated signal processing algorithms that can continuously monitor internal tissue motion in real-time during physical activities. Features of this sensor are: lightweight, flexible, mass-producible, low-cost, and thus, disposable. Disposability of the sensor is desirable for a medical device that contacts a human body since it does not require disinfection or sterilization after its usage. The wearable ultrasonic sensor technology to be developed in this proposed research program is able to measure the mechanical behavior and properties of tissues of interest quantitatively. The developed technology will enable monitoring of physical conditions of a subject outside of hospitals, clinics and laboratories. Furthermore, people will be able to wear cost-effective ultrasonic sensors that will continuously monitor their health conditions. The applications of the develop technology are not only in the areas of medical diagnosis and health monitoring but also in rehabilitation, kinesiology and sports for effective and efficient physical training. Science, engineering and clinical researchers could have benefits from this new ultrasonic sensing technology to study and understand a human physiology by monitoring tissue motion of their interest during various physical activities.