Meng Chen

Graphene‐based materials combining outstanding electrical, thermal, optical and mechanical properties have demonstrated remarkable potential for high‐performance sensing across optoelectronic, molecular, mechanical, magnetic and thermal applications. However, practical graphene sensing often involves relatively small stimulus‐induced changes in diverse electrical quantities, requiring dedicated readout electronics for accurate detection and conditioning. Existing reviews rarely treat sensing mechanisms and readout architectures in a unified system co‐design context, which leaves a gap between device demonstrations and deployable systems. To bridge device transduction and circuit interfacing, a three‐level PS–EQ–RF framework is proposed, which maps physical stimuli (PS) to electrical quantities (EQ) and to readout features (RF). Guided by the framework, this review organizes graphene‐based sensors according to electrical output characteristics into four categories: voltage‐source, current‐source, resistive (RS), and capacitive (CS) sensors. Key circuit modules, representative readout topologies, and practical implementations are analyzed for each category. We further provide system‐level co‐design guidelines, including metric mapping, architecture selection, low‐noise design, and mitigation of nonidealities, and discuss the evolution, remaining bottlenecks, and future directions of graphene‐based sensing systems. This review aims to provide a systematic view of graphene‐based sensing systems and to accelerate the transition of graphene‐based sensing technologies from laboratory prototypes to practical applications.

Owing to the unique linear Dirac-cone dispersion of graphene, graphene field-effect transistors (GFETs) exhibit advantages including high carrier mobility and ambipolar transport. Leveraging these properties, GFETs provide a promising route for broadband response from terahertz (THz) to ultraviolet wavelengths and self-powered photodetection at room temperature based on photothermoelectric (PTE) effect. However, the absence of a unified modeling framework has hindered systematic device optimization and circuit-level implementation. This work presents a general modeling methodology that couples dark state transport, PTE conversion, and intrinsic noise into an integrated framework. Three sub-models are developed for the drain-to-source current and transconductance: a uniform drift model with minimum complexity, a high carrier density model for the high carrier density regime, and a low carrier density model applicable near the charge neutrality point. A virtual optical power port is introduced to represent optical excitation within circuit simulations, enabling co-design with readout electronics. Illuminated state behavior is described by the Seebeck coefficient derived from Mott's formula combined with a hot electron temperature profile. Noise is modeled using Johnson–Nyquist and 1/f components. Experimental validation on CVD-grown GFETs under 0.288 THz illumination demonstrates strong agreement between predictions and measurements. This work establishes a systematic modeling framework for GFET PTE detectors by integrating I–V characteristics, PTE response as well as noise behavior into a unified scheme. The framework provides a reliable foundation for device performance optimization, readout circuit design, thereby accelerating the transition of GFET PTE detectors from laboratory prototypes to practical optoelectronic systems.

The frequency spectra and polarization states of terahertz waves can convey significant information about physical interactions and material properties. Compact and miniaturized on-chip platforms for effective capturing of these quantities are being extensively investigated because of their promising potential for paramount applications of terahertz technology such as in situ sensing and characterization. Here, we present a metamaterial-graphene hybrid device that integrates the functions of photodetection, wavelength, and polarization selectivity into a monolithic architecture. Leveraging the ultrahigh design freedom of metamaterial optical properties and the electronically controllable hot-carrier-assisted photothermoelectric effect in graphene, our detector shows resonantly enhanced photoresponse at two specific target wavelengths with orthogonal polarizations. We demonstrate its versatile capabilities for spectrally selective and polarization resolved imaging on a single-chip platform that is free from advanced optical components. Our strategy is beneficial to the future development of multifunctional, compact, and low-cost terahertz sensors.

A terahertz (THz) amplifier based on graphene plasmonic crystal is presented in this paper. The amplifier is composed of periodic graphene-silicon arrays, and graphene is used as the THz wave gain medium due to its negative conductivity at a certain temperature and bias voltage. The plasmonic bandgap and cascade amplification effect effectively improve the gain of the THz wave in a single slow light mode at the photonic band edge, which greatly increase the effective interaction distance of THz waves in the graphene with a limited gain coefficient and gain medium thickness. Moreover, with the thermal and electronic control on the conductivity and refractive index of graphene, the operating frequency and amplification efficiency of this device can be broadly tuned. The results show that a THz output with a gain of larger than 30 dB and $Q$ value of 720 is achieved in this device. This device has a great potential application in the THz communication, imaging, and radar system integrated with other THz solid-state electronic sources and detectors.