Integrating High Frequency Whispering-Gallery-Mode Phononic Cavities with Efficient Electrically-Small Antennas: Pushing the Limits of Wireless Passive Micro-Sensing

该项目旨在探索并结合新颖的微尺度谐振器设计和极小的天线，以建立一个不需要电源的无线传感平台，并利用经济规模以极低的价格提供卓越的性能。该平台一旦实现，将通过提供远程和非侵入性测量患者生命体征的灵活性，对医学传感范式产生重大影响。尽管在过去的几十年里微电子领域取得了巨大的技术进步，但医疗工业中使用的传感设备的规模与微型传感器领域的最新技术之间存在差距。具体来说，监测呼吸频率和呼吸模式的设备由于布线过多，给患者带来了不便。本项目提出的平台可以显著缩小监测呼吸速率所需设备的尺寸。同样的技术可以用于连续监测温度（包括核心体温）、心率、血压、摄氧量等，而无需更换电池。数据收集可以通过一个简单而小巧的装置来实现，这个装置可以与智能手机通信。主要研究人员参加了美国国家科学基金会支持的青年企业家和学者职业发展指导计划（CAMP-YES）和中佛罗里达大学的研究和指导活动（RAMA）计划，这两个计划都促进了代表性不足的本科生的研究经验。本项目开发的资源将通过招募学生参与本研究，帮助主要研究人员进一步为这些项目做出贡献。该项目的主要目标是通过探索与超小型高效天线集成的高质量因数(Q)压电高频谐振器，实现极小的无线无源传感器。在这项工作中，将首次展示压电超晶金刚石平台中的低语通道模式声子腔，目标是在1ghz左右的高频下实现高耦合因子和高质量因子。选择耳语廊模式以避免锚损失（能量损失的主要来源），选择金刚石衬底以尽量减少高频内摩擦损失的影响。如此大的耦合和Q值可以实现极小尺寸（1厘米x 1厘米，包括天线）的无线传感器，其读数范围为几米。研究工作包括：1)研究高频金刚石压电谐振器损耗的物理特性；2)在薄膜金刚石压电平台上实现低语通道模式声子腔；3)将声子腔与高效电小天线集成开发无源无线传感器。这种传感器可以比在类似频率下工作的其他无线传感器小几个数量级。该项目所针对的极小无线传感器的成功演示将对广泛的遥感应用产生重大影响，包括医疗健康监测和诊断、环境监测和工业控制。

This project aims to explore and combine novel micro-scale resonator designs with extremely small antennas to build a wireless sensing platform that does not require power sources and takes advantage of the economy scale in delivering exceptional performance at very low price-points. This platform, once realized, is believed to make a significant impact on medical sensing paradigms by offering flexibility in remote and nonintrusive measurement of patients vital signs. Despite the tremendous technological progress made in the field of microelectronics during the past few decades, there exists a gap between the scale of sensing apparatus used in medical industry and the state-of-the-art in the field of miniaturized sensors. Specifically, the devices monitoring respiration rate and breathing pattern are inconvenient for the patients due to excessive wiring. The platform proposed in this project can significantly scale down the size of the equipment required for monitoring breathing rate. The same technology can be adapted for continuous monitoring of the temperature (including the core body temperature), the heart rate, blood pressure, oxygen intake, etc. without the need for changing the battery. The data collection can be achieved by a simple and small gadget that could communicate with smartphones. The principal investigators are participating in the NSF-supported Career Advancement Mentoring Program for Young Entrepreneur and Scholars Program (CAMP-YES) and the Research and Mentoring Activities (RAMA) program at the University of Central Florida, both of which promote research experience for underrepresented undergraduate students. The resources developed in this project will assist the principal investigators in furthering their contributions to these programs by recruiting students to engage in this research. The main objective of this project is to enable extremely-small wireless passive sensors by exploring exceptionally high quality factor (Q) piezoelectric-based high-frequency resonators integrated with ultra-small highly-efficient antennas. In this work, for the first time, whispering-gallery mode phononic cavities in a piezoelectric-on-ultrananocrystalline diamond platform will be demonstrated with the goal of achieving high coupling factor and high quality factor at high frequencies around 1 GHz. The whispering gallery mode is chosen to evade the anchor-loss (a major source of energy loss) and the diamond substrate is chosen to minimize the effect of internal friction losses at high frequencies. Such large values of coupling and Q could enable extremely-small size ( 1 cm x 1 cm including the antenna) wireless sensors with a readout range of a few meters. The tasks include: 1) Studying the physics of loss in high frequency piezoelectric-on-diamond resonators, 2) Implementation of whispering-gallery mode phononic cavities in the thin-film piezoelectric-on-diamond platform, 3) Integration of the phononic cavities with highly-efficient electrically-small antennas to develop passive wireless sensors. Such sensors can be orders of magnitude smaller than other wireless sensors operating at similar frequencies. Successful demonstration of extremely small wireless sensors targeted in this project will have a significant impact on a wide range of remote sensing applications including medical health monitoring and diagnosis, environmental monitoring, and industrial control.