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

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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.