CAREER: Integrated Research and Education on Self-Activated, Transparent Harmonics-Based Wireless Sensing Systems Using Graphene Bioelectronics

最近，物联网通过收集和分析可穿戴微纳米级传感器的生物信息，在具有成本效益和长期健康监测方面得到了普及。尽管无电池微型传感器可以实现廉价、长寿命和免维护的运行，但这些微型传感器通常会受到不必要的电磁干扰，如杂波、回波和多径衰落，这大大降低了信噪比和无线探测范围。为了克服这些挑战，该研究项目将研究一种新型的自供电、化学调谐谐波转发器作为无线生物传感器。谐波生物传感器由全石墨烯天线和集成电路组成（石墨烯基本上是石墨的单原子层），可制成透明、轻质、柔性和生物相容性的医疗应用，从而使隐形眼镜传感器成为可能，用于低成本、便携式和连续诊断病原体细菌、蛋白质和多功能生物分子标记。提出的无线生物传感技术可能会导致各种应用，例如检测病毒性眼睛感染，眼表面肿瘤和眼压。此外，该项目还将把研究整合到韦恩州立大学的新课程和外展活动中（例如，ReBUILDetroit计划，Richard Barber跨学科研究计划和WSU STEM日），以招募底特律大都会地区代表性不足的K-12学生，并提高他们在射频（RF）工程和生物医学电子方面的兴趣。本研究项目的目标是研究基于全石墨烯射频和生物电子学的低噪声，节能的无线微传感器系统。本研究的关键科学进展在于基于谐波的生物传感技术，该技术采用全无源、化学可重构的应答器作为谐波生物传感器，实现实时、远程的无线生物传感。谐波生物传感器与传统的后向散射传感器有着本质的区别，它发射和检测正交频率的信号，可以对电磁干扰和人体后向散射杂波进行更大的检测范围。利用石墨烯晶体管独特的双极性和可调谐电子特性，将生物传感器和倍频器的功能结合在一个模块中，用简单的石墨烯生物电子电路就可以实现谐波生物传感器。此外，这种生物敏感的射频应答器可以连接到一个透明的双频石墨烯天线上，该天线放置在柔性的生物相容性衬底上。生物分子（如感染性或生物威胁因子）在石墨烯谐波生物传感器上的选择性结合可以通过发射单调射频信号并检测后向散射二次谐波的强度进行无线监测，因为频率转换效率会随着生物分子浓度的变化而改变。如果成功，这种小巧透明的石墨烯谐波生物传感器可以集成在软性隐形眼镜上，以灵敏地检测目标病原体、感染性病原体、疾病或感兴趣的代谢变化，并在没有任何电源或复杂电路的情况下无线传输数据。随着进一步的发展，所提出的无线生物传感器可以在医疗监测方面产生广泛的影响。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

The internet-of-things has recently gained popularity in the cost-effective and long-term health monitoring, enabled by collecting and analyzing biological information from wearable micro- and nano-scale sensors. Although battery-free micro-sensors can achieve inexpensive, long-lived and maintenance-free operation, these miniature sensors usually suffer from unwanted electromagnetic interferences, such as clutters, echoes, and multipath fading, which greatly reduce the signal-to-noise ratio and the wireless interrogation range. To surmount these challenges, this research project will investigate a new class of self-powered, chemically-tuned harmonic transponders as wireless biosensors. The harmonic biosensor consists of all-graphene antenna and integrated circuit (graphene is, basically, a single atomic layer of graphite), which can be made transparent, light-weight, flexible, and biocompatible for medical applications, thus making possible a contact lens sensor for low-cost, portable, and continuous diagnosis of pathogen bacteria, proteins, and versatile biomolecular markers. The proposed wireless bio-sensing technology may lead to various applications, such as detection of viral eye infections, ocular surface tumors, and intraocular pressure. In addition, the project will also integrate the research into the new courses and outreach activities in Wayne State University (e.g., ReBUILDetroit Program, Richard Barber Interdisciplinary Research Program, and WSU STEM Days) for recruiting under-represented and K-12 students in the Detroit metropolitan area and promoting their interest in pursuing a career in radio-frequency (RF) engineering and biomedical electronics. The goal of this research project is to investigate the low-noise, energy-efficient wireless micro-sensor system based on all-graphene RF- and bio-electronics. The key scientific advance of this research lies in the harmonics-based bio-sensing technique, which uses a fully passive and chemically reconfigurable transponder as a harmonic biosensor to achieve real-time and long-range wireless bio-sensing. Fundamentally different from conventional backscatter sensors, the harmonic biosensor, launching and detecting signals of orthogonal frequencies, can enable longer detection range against electromagnetic interferences and human-body backscatter clutters. The harmonic biosensor can be realized with a simple graphene-based bioelectronic circuit which combines functions of a biosensor and a frequency multiplier into a single module, based on the unique ambipolar and tunable electronic properties of graphene transistors. Moreover, this bio-sensitive RF transponder can be connected to a transparent, dual-band graphene antenna placed onto the flexible biocompatible substrate. The selective binding of biomolecules, such as infectious or bio-threat agents, on the graphene harmonic biosensor can be wirelessly monitored by launching a monotone RF signal and detecting the strength of the backscattered second harmonic, as the frequency conversion efficiency is altered by the biomolecular concentration. If successful, the compact and transparent graphene harmonic biosensor can be integrated on the soft contact lens to sensitively detect targeted pathogen bacteria, infectious agents, diseases, or metabolic changes of interest, and wirelessly transmit data without any power source or sophisticated circuit. With further development, the proposed wireless biosensors can have broad impacts in healthcare monitoring.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.