Ultrathin Parylene C-based sensitivity-gain nanoplasmonic sensor integrated on VCSEL for Aß42 detection.

As Alzheimer's disease prevalence continues to rise, there is an increasing demand for efficient on-chip biosensors capable of early biomarker detection. This study presents a novel biosensor chip leveraging vertical cavity surface emitting laser (VCSEL) technology, with Parylene C serving as the antibody coupling layer and utilizing a streamlined one-step antibody modification method. Integration of Parylene C enhances chip sensitivity from 34.28 µW/RIU to 40.32 µW/RIU. Moreover, post-testing removal of Parylene C enables chip reusability without significant alteration of results. The sensor demonstrates effective detection of Aß42, an Alzheimer's biomarker, exhibiting a linear range of 1-200 ng/mL and a detection limit of 0.26 ng/mL. These findings underscore the reusability and reliability of the ultrathin Parylene C-based VCSEL biosensor chip, highlighting its potential for point-of-care Alzheimer's disease diagnosis.

Terahertz Liquid Biosensor Based on A Graphene Metasurface for Ultrasensitive Detection with A Quasi-Bound State in the Continuum.

The concept of a quasi-bound state in a continuum (QBIC) has garnered significant attention in various fields such as sensing, communication, and optical switching. Within metasurfaces, QBICs offer a reliable platform that enables sensing capabilities through potent interactions between local electric fields and matter. Herein, a novel terahertz (THz) biosensor based on the integration of QBIC with graphene is reported, which enables multidimensional detection. The proposed biosensor is distinctive because of its ability to discern concentrations of ethanol and N-methylpyrrolidone in a wide range from 100% to 0%, by monitoring the changes in the resonance intensity and maximum wavelet coefficient. This approach demonstrates an excellent linear fit, which ensures robust quantitative analysis. The remarkable sensitivity of our biosensor enables it to detect minute changes in low-concentration solutions, with the lowest detection concentration value (LDCV) of 0.21 pg mL-1 . 2D wavelet coefficient intensity cards are effectively constructed through continuous wavelet transforms, which presents a more accurate approach for determining the concentration of the solution. Ultimately, the novel sensing platform offers a host of advantages, including heightened sensitivity and reusability. This pioneering approach establishes a new avenue for liquid-based terahertz biosensing.

Label-free integrated microfluidic plasmonic biosensor from vertical-cavity surface-emitting lasers for SARS-CoV-2 receptor binding domain protein detection.

The nanoplasmonic sensor of the nanograting array has a remarkable ability in label-free and rapid biological detection. The integration of the nanograting array with the standard vertical-cavity surface-emitting lasers (VCSEL) platform can achieve a compact and powerful solution to provide on-chip light sources for biosensing applications. Here, a high sensitivity and label-free integrated VCSELs sensor was developed as a suitable analysis technique for COVID-19 specific receptor binding domain (RBD) protein. The gold nanograting array is integrated on VCSELs to realize the integrated microfluidic plasmonic biosensor of on-chip biosensing. The 850 nm VCSELs are used as a light source to excite the localized surface plasmon resonance (LSPR) effect of the gold nanograting array to detect the concentration of attachments. The refractive index sensitivity of the sensor is 2.99 × 106 nW/RIU. The aptamer of RBD was modified on the surface of the gold nanograting to detect the RBD protein successfully. The biosensor has high sensitivity and a wide detection range of 0.50 ng/mL - 50 µg/mL. This VCSELs biosensor provides an integrated, portable, and miniaturized idea for biomarker detection.

In Situ Growth of Graphene Catalyzed by a Phase-Change Material at 400 °C for Wafer-Scale Optoelectronic Device Application.

The use of metal foil catalysts in the chemical vapor deposition of graphene films makes graphene transfer an ineluctable part of graphene device fabrication, which greatly limits industrialization. Here, an oxide phase-change material (V2 O5 ) is found to have the same catalytic effect on graphene growth as conventional metals. A uniform large-area graphene film can be obtained on a 10 nm V2 O5 film. Density functional theory is used to quantitatively analyze the catalytic effect of V2 O5 . Due to the high resistance property of V2 O5 at room temperature, the obtained graphene can be directly used in devices with V2 O5 as an intercalation layer. A wafer-scale graphene-V2 O5 -Si (GVS) Schottky photodetector array is successfully fabricated. When illuminated by a 792 nm laser, the responsivity of the photodetector can reach 266 mA W-1 at 0 V bias and 420 mA W-1 at 2 V. The transfer-free device fabrication process enables high feasibility for industrialization.

Transfer-Free CVD Growth of High-Quality Wafer-Scale Graphene at 300 °C for Device Mass Fabrication.

Direct chemical vapor deposition of graphene on semiconductors and insulators provides high feasibility for integration of graphene devices and semiconductor electronics. However, the current methods typically rely on high temperatures (>1000 °C), which can damage the substrates. Here, a growth method for high-quality large-area graphene at 300 °C is introduced. A multizone furnace with gradient temperature control was designed according to a computational fluid dynamics model. The crucial roles of the chamber pressure in the film continuity and hydrogen composition in the graphene defect density at low temperature were revealed. As a result, a uniform graphene film with the Raman ratio ID/IG = 0.08 was obtained. Furthermore, a technique of laminating single-crystal Cu foil as a sacrificial layer on the substrate was proposed to realize transfer-free growth, and a wafer-scale graphene transistor array was demonstrated with good performance consistency, which paves the way for mass fabrication of graphene devices.

Graphene-silicon-graphene Schottky junction photodetector with field effect structure.

Graphene has unique advantages in ultrabroadband detection. However, nowadays graphene-based photodetectors cannot meet the requirements for practical applications due to their poor performance. Here, we report a graphene-silicon-graphene Schottky junction photodetector assisted by field effect. Two separate graphene sheets are located on both sides of the n-doped silicon to form two opposite lateral series heterojunctions with silicon, and a transparent top gate is designed to modulate the Schottky barrier. Low doping concentration of silicon and negative gate bias can significantly raise the barrier height. Under the combined action of these two measures, the barrier height increases from 0.39 eV to 0.77 eV. Accordingly, the performance of the photodetector has been greatly improved. The photoresponsivity of the optimized device is 2.6 A/W at 792 nm, 1.8 A/W at 1064 nm, and 0.42 A/W at 1550 nm, and the on/off photo-switching ratio reaches 104. Our work provides a feasible solution for the development of graphene-based optoelectronic devices.

An LSPR Sensor Integrated with VCSEL and Microfluidic Chip.

The work introduces a localized surface plasmon resonance (LSPR) sensor chip integrated with vertical-cavity surface-emitting lasers (VCSELs). Using VCSEL as the light source, the hexagonal gold nanoparticle array was integrated with anodic aluminum oxide (AAO) as the mask on the light-emitting end face. The sensitivity sensing test of the refractive index solution was realized, combined with microfluidic technology. At the same time, the finite-difference time- domain (FDTD) algorithm was applied to model and simulate the gold nanostructures. The experimental results showed that the output power of the sensor was related to the refractive index of the sucrose solution. The maximum sensitivity of the sensor was 1.65 × 106 nW/RIU, which gives it great application potential in the field of biomolecular detection.

Remote Phonon Scattering in Two-Dimensional InSe FETs with High-κ Gate Stack.

This work focuses on the effect of remote phonon arising from the substrate and high-κ gate dielectric on electron mobility in two-dimensional (2D) InSe field-effect transistors (FETs). The electrostatic characteristic under quantum confinement is derived by self-consistently solving the Poisson and Schrödinger equations using the effective mass approximation. Then mobility is calculated by the Kubo⁻Greenwood formula accounting for the remote phonon scattering (RPS) as well as the intrinsic phonon scatterings, including the acoustic phonon, homopolar phonon, optical phonon scatterings, and Fröhlich interaction. Using the above method, the mobility degradation due to remote phonon is comprehensively explored in single- and dual-gate InSe FETs utilizing SiO2, Al2O3, and HfO2 as gate dielectric respectively. We unveil the origin of temperature, inversion density, and thickness dependence of carrier mobility. Simulations indicate that remote phonon and Fröhlich interaction plays a comparatively major role in determining the electron transport in InSe. Mobility is more severely degraded by remote phonon of HfO2 dielectric than Al2O3 and SiO2 dielectric, which can be effectively insulated by introducing a SiO2 interfacial layer between the high-κ dielectric and InSe. Due to its smaller in-plane and quantization effective masses, mobility begins to increase at higher density as carriers become degenerate, and mobility degradation with a reduced layer number is much stronger in InSe compared with MoS2.