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Exhaled breath can be used for early detection and diagnosis of diseases, monitoring metabolic activity, and precision medicine. In this work, we design and simulate a microwave sensor in which thin graphene aerogels are integrated into rectangular microwave waveguides. Graphene aerogels are ideal sensing platforms for gases and volatile compounds as they combine extremely high surface-to-volume ratio and good electrical conductivity at RF and microwave frequencies. The latter is modified by exposure to different gases, and -when integrated into a waveguide- these changes result in significant shifts in transmission and reflection scattering parameters. We model the aerogel as a graphene grid with hexagonal openings of size 22.86×10.16×0.1 mm3, characterized by an air volume equal to about 90 % of its entire volume. This grid is used as a building block for modeling thicker samples (up to 9 mm), To simulate the variation in the dynamic conductivity of the graphene sheets as a consequence of the absorption of gaseous molecules, a sweep of the chemical potential from 0.0 e V to 0.5 e V with steps of 0.1 e V was used. The results show a significant variation of the waveguide transmission scattering parameters resulting from the gas-induced modification of the graphene conductivity, and hence the potential of the proposed sensor design for breath analysis.

We report room temperature terahertz detection in hBN/graphene/hBN heterostructures, integrated in top-gated field effect transistors. The record combination of high-speed (response time < 1 ns) and high sensitivity (noise equivalent power ~ 100 pWHz-1I2) is enabled by the photo-thermoelectric effect and paves the way for the design of ultrafast graphene arrays in the far infrared, opening concrete perspectives for targeting ultrafast applications.

Graphene field-effect transistor (FET) has been successfully demonstrated for terahertz (THz) detection at room temperature. This graphene FET has a differential feeding structure and a high output impedance up to several thousand Ohms. These characteristics significantly challenge the antenna design, especially a high-performance antenna. To alleviate this issue, this paper presents a circularly bended dipole antenna on silicon substrate. The results show that, this novel antenna features a differential pair, a high impedance of 5000 Ohms, a high gain of 9.47 dBi, and also a narrow bandwidth of 3 GHz to filter out input noise. This antenna is a very good candidate for inherent integration, and will significantly improve the performance of the graphene-based THz detector.

In this work an advanced overview in the field of near-infrared silicon photodetectors, is presented. Proposed photodetectors are based on the internal photoemission effect through a Schottky junction and their fabrication results completely compatible with the silicon technology. Taking advantage of both new structures and new two-dimensional emerging materials, a progressive increase in device performance has been demonstrated along the last years. Our insights show that silicon devices based on the internal photoemission effect are already suitable for power monitoring applications and they could play a key role in the telecommunications opening new frontiers in the field of low-cost silicon photonics. © 2014 AEIT.