CAREER: Leveraging the Dielectric Waveguide Properties of the Human Body for Ultra-Efficient "Unawearables"

这项研究的主要目标是大幅降低在身体周围交流信息所需的电力，以帮助实现下一代可穿戴医疗和健康设备。目前的可穿戴设备倾向于使用蓝牙在身体周围进行通信，尽管操作相当可靠，但能源效率极低，导致设备电池续航时间较短。例如，在可穿戴医疗贴片上发现的传统蓝牙设备将向各个方向发射无线电波，只有智能手表或智能手机上无线电接收到的发射能量的0.000001，这在一定程度上是因为人体在2.4 GHz处大量吸收电磁能量。为了提高无线通信的效率，拟议的研究致力于利用人体本身作为通信渠道。具体地说，这种方法不是向各个方向传播信息，这会导致严重的能源效率低下和隐私/安全问题，而是利用放置在智能手表带内、可穿戴式贴片或智能手机上的有线线圈来产生安全而高效地通过人体的小磁场。人体在低得多的目标频率(10-50 MHz)下的电磁特性比2.4 GHz时更有利，使效率高达10%，并迅速从人体下降，从而实现固有的更高效、更安全和更私密的通信。产生的磁场强度低于地球的自然磁场，比蓝牙或手机小一个数量级，因此被认为是安全的。为了证明这项技术的有效性，将开发几个线圈、电路和系统原型，并对各种与医疗保健相关的应用进行测试，例如助听器和可穿戴式血糖监测仪。该计划还包括一项与研究目标协同的教育计划，包括面向K-12和工程学专业代表性不足的学生。所提出的通信系统特别利用生物组织的高介电常数来获得高效率。尽管在很大程度上是磁惰性的，但由于组织的高介电常数，以10-50 MHz传递到人体的磁能增强了近场和中场分量，同时还产生了完全在内部反射的远场分量，从而创建了一种基于人体的介质波导式结构。这份职业计划的目标是开发描述这种行为的物理模型，优化线圈以降低跨体路径损耗，并设计、制造和测试集成电路以实现高效的跨体通信。成功的开发将使身体区域网络收发器的运行效率比传统技术高得多，使可穿戴设备比以前更小，电池寿命更长，从而在医疗保健、健康和个人信息娱乐系统中开辟新的途径和应用。为了帮助代表不足群体的成员更广泛地参与STEM领域，将在K-12外联活动上讨论相关的研究成果，例如，包括在夏季技术夏令营创造互动式身体-区域网络通信体验。

The primary objective of this research is to dramatically reduce the power needed to communicate information around the body in order to help enable the next generation of wearable medical and wellness devices. Current wearables tend to utilize Bluetooth for communication around the body, which despite operating fairly reliably, is extremely energy inefficient, resulting in poor device battery life. A conventional Bluetooth device found on a wearable medical patch, for example, will broadcast radio waves in all directions, with as little as 0.000001% of the transmitted energy received by the radio on your smartwatch or smartphone, in part due to large absorption of electromagnetic energy by the human body at 2.4GHz. To improve the efficiency of wireless communication, the proposed research endeavors to leverage the human body itself as a communication channel. Specifically, rather than broadcasting information in all directions, which has severe energy inefficiencies and privacy/security concerns, the proposed approach utilizes wired coils placed within the band of a smartwatch, in a wearable patch, or on a smartphone, to generate small magnetic fields that safely and efficiently pass through the body. The electromagnetic properties of the human body at the much lower targeted frequencies (10-50MHz) are more favorable than at 2.4GHz, enabling efficiencies as high as 10%, with rapid fall-off away from the body, for inherently more efficient, secure, and private communications. The generated magnetic fields are of lower strength than Earth's natural magnetic field, and orders of magnitude less than Bluetooth or mobile phones, and are thus considered to be safe. To demonstrate the effectiveness of this technique, several coil, circuit, and system prototypes will be developed and tested for a variety of healthcare-related applications such as in hearing aids and wearable glucose monitors. The program also includes an education plan that is synergistic with the research goals, including outreach to K-12 and underrepresented students in engineering. The proposed communication system specifically leverages the high dielectric constant of biological tissue to attain high efficiency. Despite being largely magnetically-inert, magnetic energy delivered to the body at 10-50MHz has, due to the high dielectric constant of tissue, enhanced near- and mid-field components, while also generating far-field components that totally-internally reflect to create a human-body-based dielectric waveguide-like structure. The objectives of this CAREER proposal are to develop physical models that describe this behavior, optimize coils for low trans-body path loss, and design, fabricate, and test integrated circuits to communicate across the body at high efficiency. Successful development will enable body-area networking transceivers that operate at much higher efficiency than conventional techniques, enabling wearable devices that are smaller and have longer battery life than before, thereby opening up new avenues and applications in healthcare, wellness, and personal infotainment systems. To help broaden participation of members of underrepresented groups in STEM fields, related research results will be discussed at K-12 outreach events, including, for example, the creation of interactive body-area network communication experiences at summer technology camps.