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Triple Gate Polycrystalline-Silicon-Based Ion-Sensitive Field-Effect Transistor for High-performance Aqueous Chemical Application
摘要： In this study, we developed a polycrystalline-silicon (poly-Si) thin-film transistor (TFT)-based, high-performance ion-sensitive field-effect transistor (ISFET) pH sensor that far surpasses the sensitivity of dual-gate pH sensors. A Triple gate structure on the same plane as the channel of the ISFET has been proposed to enhance the pH sensitivity. In a poly-Si TFT-based ISFET, a Triple gate is more advantageous than a bottom-gate for increasing capacitive coupling with the top-gate. As a result, the pH sensitivity by Triple gate (TG) mode detection using the Triple gate is much greater than single-gate (SG) mode detection using the top-gate, or dual-gate (DG) mode detection using the bottom-gate. The sensitivity of the TG mode greatly increased compared with the sensitivity of the conventional SG mode or DG mode. The measured pH sensitivity was 57.75 ± 0.77 mV/pH in the SG mode, 467.08 ± 9.92 mV/pH in the DG mode. In particular, the TG mode gives a maximum sensitivity of 1283.56 ± 45.54 mV/pH for a sensing membranes having a theoretical Nernstian pH response (59.15 mV/pH at 25 °C). Furthermore, we measured the hysteresis and drift characteristics, and found that the TG mode has improved non-ideal behavior compared to the SG and DG modes. Therefore, the poly-Si TFT-based TG ISFET pH sensor has the potential to become a promising biosensor application platform, with excellent sensitivity and stability.
关键词： ion-sensitive field effect transistor,Triple gate,capacitive coupling effect
更新于2025-09-23 15:22:29
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Effective light polarization insensitive and omnidirectional properties of Si nanowire arrays developed on different crystallographic planes
摘要： In this paper, fabrication of vertical Si nanowire arrays (SiNWAs) by a facile metal assisted electroless etching approach on different crystallographic planes of Si has been reported. A very low specular reflectance (Rspec) of 0.04% and 0.03% has been achieved in the whole visible range for SiNWAs grown on Si(100) and Si(111) oriented substrates, respectively. High broadband enhancement has been detected for vertical SiNWAs due to multiple scattering paths inside the nanowire arrays. On the other hand, inclined nanowires showed a fascinating behavior at the longer wavelength regime, where light gets the longer path to reflect back-forth and ease to reflect back outward at normal incidence. Moreover, for [100] SiNWAs, transverse electric (TE) field component demonstrates the strong polarization insensitive properties at the expense of transverse magnetic (TM) field component with a minimum reflectance of < 2% up to 1200 nm. The [100] SiNWAs demonstrates extra-ordinary omnidirectional properties at θB ≥ 58o. Theoretical validation of COMSOL with an effective medium approach reveal the effective dipole coupling and the presence of strong absorption modes for vertical SiNWs at a typical wavelength regime. The highly bound states of the particle tunneling through classical forbidden region shows a strong enhancement in light absorption effect.
关键词： nanocavities,Si nanowires,light coupling effect,omnidirectional,polarization
更新于2025-09-23 15:22:29
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Graphene disks for frequency control of terahertz waves in broadband applications
摘要： The terahertz (THz) gap lying between the microwave and optical parts of the electromagnetic spectrum has attracted immense attention due to its applications between radiofrequency (RF)/microwave and photonic systems. A structure consisting of a graphene sheet sandwiched between two graphene disks is introduced herein to control the reflection, absorption, and transmission of THz waves. The proposed metamaterial structures are designed analytically using transmission line theory. Also, the dimensions of the structure and the electrical gating of the graphene are optimized utilizing a genetic algorithm. The structure is simulated using two different methods: (1) a circuit model based on transmission line theory and (2) commercial full-wave software based on the finite element method, which are verified by the agreement between their results. Finally, the proposed method is used to design a THz filter and THz wave absorber, which are in great demand for application in modulators, sensors, detectors, and imaging systems.
关键词： Resonator,Circuit method,Coupling effect,Graphene,Genetic algorithm,Absorber design,Impedance matching
更新于2025-09-23 15:21:01
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Collectively induced exceptional points of quantum emitters coupled to nanoparticle surface plasmons
摘要： Exceptional points, resulting from non-Hermitian degeneracies, have the potential to enhance the capabilities of quantum sensing. Thus, finding exceptional points in different quantum systems is vital for developing such future sensing devices. Taking advantage of the enhanced light-matter interactions in a confined volume on a metal nanoparticle surface, here we theoretically demonstrate the existence of exceptional points in a system consisting of quantum emitters coupled to a metal nanoparticle of subwavelength scale. By using an analytical quantum electrodynamics approach, exceptional points are manifested as a result of a strong-coupling effect and observable in a drastic splitting of originally coalescent eigenenergies. Furthermore, we show that exceptional points can also occur when a number of quantum emitters are collectively coupled to the dipole mode of localized surface plasmons. Such a quantum collective effect not only relaxes the strong-coupling requirement for an individual emitter, but also results in a more stable generation of the exceptional points. Furthermore, we point out that the exceptional points can be explicitly revealed in the power spectra. A generalized signal-to-noise ratio, accounting for both the frequency splitting in the power spectrum and the system’s dissipation, shows clearly that a collection of quantum emitters coupled to a nanoparticle provides a better performance of detecting exceptional points, compared to that of a single quantum emitter.
关键词： strong-coupling effect,metal nanoparticle,power spectra,quantum emitters,quantum sensing,signal-to-noise ratio,surface plasmons,Exceptional points
更新于2025-09-23 15:19:57
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AIP Conference Proceedings [AIP Publishing PROCEEDINGS OF THE INTERNATIONAL CONFERENCE ON MATHEMATICAL SCIENCES AND TECHNOLOGY 2018 (MATHTECH2018): Innovative Technologies for Mathematics & Mathematics for Technological Innovation - Penang, Malaysia (10–12 December 2018)] PROCEEDINGS OF THE INTERNATIONAL CONFERENCE ON MATHEMATICAL SCIENCES AND TECHNOLOGY 2018 (MATHTECH2018): Innovative Technologies for Mathematics & Mathematics for Technological Innovation - Numerical study of the evanescent field coupling effect on two optical fiber sensors
摘要： In this paper, multi-sensor is proposed based on the evanescent field coupling effect on two optical fibers. The waveguide aligned side by side were numerically simulated using the beam propagation method (OptiBPM) simulator. Optical rays are confined within a waveguide by total internal reflection and closely visualized at the waveguide’s cladding interface via electromagnetic wave theory model. Distinct distances between optical fibers are considered for optical power loss and the sensor operation is explained in terms of these effects. The coupling coefficient express the products between the evanescent part of the field and the propagative part guided in the core. The performance of the device is found satisfactory to build higher order multi-sensor.
关键词： optical fiber sensors,beam propagation method,coupling effect,evanescent field
更新于2025-09-16 10:30:52
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Wavelength-dependent surface plasmon coupling electrochemiluminescence biosensor based on sulfur doped carbon nitride quantum dots for K-RAS gene detection
摘要： Although graphite phase carbon nitride quantum dots (GCN QDs) showed some advantages in the electrochemiluminescence (ECL) analytical research, the low ECL efficiency limited the potential sensing application. Herein, we synthesized sulfur doped graphite phase carbon nitride quantum dots (S-GCN QDs) to fabricate a sandwich sensor based on amplified surface plasmon coupling ECL (SPC-ECL) mode. Sulfur doping can change the surface states of QDs effectively and produced new element vacancy. As a result, the ECL efficiency of S-GCN QDs was 2.5 times over GCN QDs. Furthermore, compared with the big gap between the ECL peak of GCN QDs (620 nm) and the absorption peak of Au NPs, the doped sulfur elements in S-GCN QDs generated new ECL emission peaks at 555 nm, which was closed to the absorption peak of Au NPs at 530 nm. Due to the wavelength-dependent surface plasmon coupling effect, the ECL peak of S-GCN QDs at 555 nm had greater amplitude of enhancement in the sensing system. The proposed biosensor can quantify the K-RAS gene from 50 fM to 1 nM with a limit of detection (LOD) of 16 fM. We were the first to provide insight into the role of wavelength-dependent surface plasmon coupling in enhancing the sensitivity of ECL biosensor.
关键词： wavelength-dependent surface plasmon coupling effect,sulfur doped GCN QDs,K-RAS gene,Electrochemiluminescence
更新于2025-09-16 10:30:52
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Dual-band asymmetric optical transmission of both linearly and circularly polarized waves using bilayer coupled complementary chiral metasurface
摘要： It is highly desirable to develop asymmetric transmission (AT) devices for both linearly and circularly polarized light. However, currently existing metamaterial-based AT devices require multi-step micro-nano fabrication processes and usually realize AT responses only for linearly or circularly polarized waves, not simultaneously for both. We here propose a dual-band AT device for both linearly and circularly polarized waves in the near-infrared region by using a bilayer coupled complementary chiral metasurface, which includes a half-gammadion-shape gold (Au) structural layer and its Babinet’s complimentary copy. Unlike other multilayer AT devices working at optical frequencies, it takes less micro-nano fabrication steps. Besides, with the help of chirality and the inherent near-?eld coupling e?ect between the two complementary Au layers, the maximal AT parameters for linearly and circularly polarized waves can reach up to 0.45 and 0.56, respectively. The underlying mechanisms of dual-band AT responses are also investigated in depth from the perspectives of chirality and coupling e?ect. Our work o?ers a new and simple approach to high-performance AT devices, helps to better understand near-?led coupling e?ect in coupled complementary metasurfaces, and also expands their application ?elds.
关键词： chiral metasurface,asymmetric transmission,polarization conversion,coupling effect,near-infrared
更新于2025-09-11 14:15:04
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Plasma spatial distribution manipulation and electrical property enhancement through plasma coupling effect
摘要： Plasma pattern transition in a symmetric hybrid structure cavity device at micrometer scale is researched through microplasma interaction in intervening microchannel between adjacent cavities while manipulating electric field strength. Plasma distribution reconfiguration in central (objective) cavity is observed when sidearm (donor) cavities are ignited. As long as coupling effect occurred by modulating the electric field strength in the sidearm cavities, stable plasma pattern transition in objective cavity is obtained, exhibiting plasma pattern split from one circular spot (initial pattern) to two small circular spots (transited pattern), along with plasma peak emission intensity displacement over 100 μm to its equilibrium position. The shape of transited plasma patterns are depending on the coupling effect from sidearm cavities. The two circular spots unsymmetrically distributed if either donor cavity is ignited, and the ratio of average emission intensity between the two plasma spots is over 30%, however, which is less than 4% if coupling symmetrically occurred. The electrical and optical properties of central microplasma are also modulated, that the breakthrough voltage is decreased by 22% and emission intensity is improved by ～30%, by means of plasma coupling. The microplasma pattern formation at micrometre scale and manipulation of the electrical properties in microscale cavity implies significant value in the application of plasma transistor and signal processing.
关键词： microscale cavity,plasma pattern transition,plasma coupling effect,electric field strength,microplasma interaction
更新于2025-09-10 09:29:36
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High performance InGaN double channel high electron mobility transistors with strong coupling effect between the channels
摘要： In this paper, high performance InGaN double channel (DC) high electron mobility transistors (HEMTs) are proposed and systematically investigated. Due to the coordination of double InGaN channels, a large maximum drain current density and a distinct double-hump feature of the transconductance and frequency performance are achieved. More importantly, it is revealed that the coupling effect between the two InGaN channels is much stronger than that of the conventional GaN DC HEMTs. This characteristic leads to a remarkable enhancement in the gate voltage swing, indicating the excellent linearity of the InGaN DC HEMTs at both dc and rf conditions. Benefiting from the enhanced electron confinement in InGaN channels, the fabricated HEMTs show a low off state drain leakage current of 0.26 μA/mm and a high on/off current ratio (Ion/Ioff) of 5.1 × 106. In addition, the desirable current collapse and breakdown characteristics are also obtained. This work convincingly demonstrates the great potential and practicality of the InGaN DC HEMTs for high power and high bandwidth applications.
关键词： high power,InGaN,double channel,high electron mobility transistors,high bandwidth,coupling effect,linearity
更新于2025-09-09 09:28:46