Self-Powered Multi-Function Harmonics-Based Wireless Sensing System Using Graphene Bioelectronics
thesisposted on 01.05.2020, 00:00 authored by Mehdi Hajizadegan
We introduce a new paradigm of low-noise and low-interface wireless sensing system, which receives a radio signal at the fundamental frequency f0 and retransmits high harmonics (e.g. second harmonic 2f0) with the conversion gain being modulated by the targeted agent. Specifically, the harmonic-transponder sensor (or harmonic sensor) is based on all-graphene radio-frequency (RF) circuits. Thanks to unique properties in graphene field-effect transistors (GFETs), such as the ambipolar carrier transport and the shiftable charge neutral point, the frequency modulation and chemical/molecular sensing functions can be combined into a single RF component (i.e., chemically-sensitive modulator). By transmitting and interrogating RF signals with orthogonal frequencies, the backscattered signal can be free from severe background clutters, jamming, multipath-scattering and background electromagnetic interfaces, regardless of the sensor’s scattering cross-section. Moreover, a GFET-based RF modulator circuit may enable dual/multi-functional sensing by employing the machine learning approach to interpret output harmonics. The proposed graphene-based harmonic sensor may be used to a variety of sensing applications, including, but not limited to, real-time monitoring of chemical and gas exposures, as well as biological agents. Further development of such technique may have an impact on wearable and implantable devices, internet of things (IoTs), industry 4.0, and smart city.