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Droplet injection methods are widely used in the applications of microelectronic manufacturing, biological engineering, and 3-D printing. This work presents a new jet dispenser driven by a single piezoelectric stack that enables the capability of drop-on-demand patterning under a high working frequency (500 Hz). Due to the special designs of the jet dispenser, a broad range of liquids, whose viscosities span more than four orders of magnitude (21-665 320 cps), can be jetted. Moreover, a coupled Coulomb damping physical model is proposed, which includes an electromechanical and a dynamic model. Both the Coulomb and the fluid-solid damping are considered in the dynamic model. In order to validate the results obtained by using MATLAB/Simulink, the experiments were carried out. The injection performance of this jet dispenser has been tested by employing a self-made jetting platform. The minimum volume of a jetting droplet is about 14.4 nL with liquid wax. The error of volume uniformity among droplets does not exceed 8%, and the error of angle trajectory is about 0.17°. Furthermore, the versatility of the jet dispenser is demonstrated by printing liquid lubricant, food, glue, silver past, and a ceramic slurry in predefined patterns.

Resistive switching (RS) has been studied for several applications such as information storage and bio-inspired computing, although reliability issues still prevent their massive use. In this work, we present a novel observation of trapping activity that imposes giant random conductance fluctuations, up to 3 orders of magnitude, resembling RTN in RS devices based on TiO2, HfO2 and hexagonal boron nitride (h-BN) under reading voltages (~ 0.1 V). These events appeared reproducible for all the aforementioned RS device types in sequential measurements and under different bias. This behavior is very beneficial to ensure recognition of the device’s two-state in applications such as stochastic computing integrated circuits (ICs).

In this work, a large-area MoS2/graphene barristor device, with an electrically tunable Schottky barrier height, has been studied for detection of various gaseous analytes. The Schottky barrier height could be modulated by over 0.65 eV, allowing the drain current to be tuned by many orders of magnitude. Using diluted NO2 and NH3 gases as analytes, the performance of the barristor device was compared with individual MoS2 and graphene based planar FETs, where the barristor device outperformed its counterparts in terms of response magnitude and limit of detection. Due to the atomically thin nature of MoS2 and graphene, electric field applied to one material could not be fully screened from the other one, which allowed both materials to act as a composite structure when analyte molecules interacted with the barristor device. This apparently reversed the dopant behavior of NO2 and NH3, while increasing the device sensitivity through subthreshold operation. Both conductance and capacitance based measurements are presented to highlight the charge transfer and barrier height modulation, to support the unique sensing mechanism observed in the 2D barristor device. A lower limit of detection in low ppb is established for NO2 and low ppm for NH3, which could be further tuned by altering gate-drain bias conditions.

The development of low-cost impedance spectroscopy devices is limited by the capabilities of low-cost hardware. Impedance spectroscopy requires high accuracy over a large bandwidth and dynamic range for most applications. In this paper, back-end signal processing solutions are examined and implemented to improve both the bandwidth and dynamic range of a typical low-cost impedance analyser without modifying the hardware. The bandwidth is improved by undersampling the input waveforms and reconstructing the signals based on the known frequency information. The bandwidth can be increased by multiple orders of magnitude and the limiting factor of the system becomes amplifier bandwidth and the Analog-to-Digital Converter (ADC) sample-and-hold circuit. Despite allowing signals to become orders of magnitude larger than the ADC range, the original signal can be reconstructed based on the measured saturated signal. This saturation technique more than doubles the dynamic range for any given accuracy requirement.

In this work, we study thickness down-scaling as a technique to miniaturize piezoelectric ultrasound transducers while preserving a frequency of operation that falls in the 40–100 kHz range, where airborne ultrasound can propagate over several meters distances and attenuation is $100\,\,\mu \text{m}\,\,\times 100\,\,\mu \text{m}$ . We compare this performance to the sensitivities of ultrasound sensors recently published in literature, showing an increase in Rx sensitivity per unit area between 1 and 2 orders of magnitude. [2021-0094]

This paper proposes a novel flexible tactile sensor array for dynamic triaxial force measurement. Piezoresistive nanofibers, which are fabricated via the electrospinning method and are composed of multi-wall carbon nanotubes (MWCNTs) and thermoplastic polyurethane (TPU), are selected as the sensing material. The sensitive piezoresistive layer, which has micron-scale thickness, is wrapped in polydimethylsiloxane (PDMS) with a bumped surface. This structure not only detects triaxial forces of different magnitudes and frequencies, but also can recognize the shape, size, and curvature of external objects using multiple measuring points of the sensor. When the sensor is subjected to normal forces at different frequencies, the measuring voltage shows good responses with variations of less than 1.21 %. When the sensor is subjected to shear forces, the coefficient of variation is less than 2.05%. In addition, when the sensor is stressed at multiple measuring points, the voltage response errors between the different points are less than 5.29%. The sensor shows high sensitivity (with a resistance change that can reach four orders of magnitude) and high response-speeds (response within 62 ms) in validation experiments. The proposed flexible sensor is efficient in triaxial force detection and has the potential for application to prosthetic hands and wearable devices.

This paper proposes a new structure named a Side Contact lateral Doping Field Effect Diode (SLFED) to overcome the short channel effects of a regular field effect diode (FED). The fabrication of this new structure is simple that can be fabricated by the standard CMOS process technology, and it offers good electrical characteristics. Furthermore, a comprehensive analysis of FEDs has presented. Our results show that the calculated Ion/Ioff ratio is several orders of magnitude larger than of the regular FED. For simulating the structures, we have applied semiconductor device simulation tools.

Ultraviolet photodetectors have several critical applications in communications, early missile launch detection, pollution monitoring, and bacterial fluorescence detection. Wide-bandgap metal oxide semiconductors have proven to be high performance ultraviolet photodetectors with some photoresponsivities reaching several orders of magnitude greater than solid state commercial devices and even photomultiplier tubes. However, analysis and design of metal-oxide photodetectors is complicated by oxygen adsorption and photodesorption at the surface. A limited understanding of this adsorption phenomenon hinders the development of new UV photodetectors. This paper clarifies the adsorption and photodesorption process and makes analysis of metal-oxide photoconductors tractable. Several models of oxygen adsorption, oxygen desorption, and adsorption-controlled conduction from across disciplines are summarized. We discuss each model’s use in their intended context, implications for design, fitting parameters, and limitations. We conclude with an argument that current models are insufficient for describing high-gain metal oxide ultraviolet photodetectors, and we outline the requirements for a new model suitable for high-gain sensors.

Tunnel FET is recognized as one of the most promising candidates for ultra-low power applications due to its ultra-low off current and CMOS compatibility. However, some characteristics of TFET caused by asymmetric device structure and special conduction mechanism may make conventional topologies of logic circuits no longer applicable. Our previous work has reported that TFET stacking will result in severe current degradation, which makes traditional logic cells not applicable. In this paper, two solutions are proposed: first, from a logic cell perspective, novel hybrid TFET-MOSFET topologies of standard logic cells are proposed, which achieve more than 2 times lower hardware cost and intrinsic delay, hence up to 4 times lower area-power-delay product (APDP) than that of conventional TFET logic circuits. Compared to MOSFET logic circuits, the designs achieve almost 2 orders of magnitude lower power and up to 34 times lower APDP. Second, from a large-scale circuit perspective, an optimized digital front-end (DFE) is proposed. Taking serial peripheral interface (SPI) as an example, SPI circuit using the optimized DFE achieves 46% lower delay and 4 times lower APDP than that of traditional TFET SPI, and 3 orders of magnitude lower static power and APDP than that of MOSFET SPI.

A two-dimensional (2D) model was developed, for the first time, to describe the characteristics of the micromachined thermal expansion-based angular motion (TEAM) sensor, which has been validated by the experimental results. Scaling analysis on the performance characteristics through the 2D model was conducted to optimize the TEAM sensor’s design in terms of the normalized distances between the microheaters and temperature detectors in $x$ and $y$ directions, the thickness of the thin film, the heater width, the cavity depth, and the heater temperature. Furthermore, the proposed 2D model was normalized by two dimensionless numbers, namely Rayleigh number Ra and Peclet number Pe, with a critical Rayleigh number (Ra $^{\ast }_{\mathrm {c}} =18$ ,000) identified to differentiate linear and nonlinear operation regimes of the TEAM sensor. In particular, our 2D model is much faster than the conventional CFD model by three orders of magnitude (18.91s versus 5.5h), enabling rapid system-level optimization of the critical design parameters. Accordingly, the TEAM sensors with three pairs of platinum thermoresistive temperature sensors were designed and fabricated. The fabricated device demonstrated a normalized sensitivity of $11.8~\mu \text{V}$ /°/s/mW based on the working fluid of air, which was more than three times better than previous thermal angular motion sensors. Thus, with the experimental validation, the proposed 2D model should be a reliable tool to realize the systematical design optimization of TEAM sensors integrated with on-chip microelectronics for future industrial IoT applications. [2020-0355]

This article reports humidity sensors based on hierarchical gallium nitride (GaN) with flower-like microstructures based on a scalable hybrid approach. We have fabricated 3D dandelion flower-like GaN hierarchical microspheres with an ammonothermal- conjugated ammoni- fication method (750-1150 °C) for the humidity sensors. The GaN microspheres are analyzed by scanning electron microscopy, X-ray diffraction, Raman and Fourier-transform spectroscopic methods. It is found that the use of oleylamine in the ammonothermal-ammonification hybrid approach, plays an essential role in the GaN morphology. The GaN sensors are prepared by dip-coating the sensor materials on the interdigitated electrode and their humidity sensing performance have been characterized. The humidity sensing performance is investigated at an applied 1V AC bias, by measuring the impedance and charge transfer resistance as a function of the broad range (10 to 95%) of RH. The GaN sensor exhibits a high response of above four orders of magnitude with excellent linearity and stability within the whole measurement range, while the bare GaN humidity sensors exhibited a low response of less than two orders of magnitude with poor linearity and stability. We have also proposed a possible charge transfer mechanism and studied the influence of the defect degree on the sensing performance of the GaN humidity sensors.

This paper focuses on the development of a thin normal-shear force sensor based on the use of a supercapacitive sensing mechanism. The sensor has a quad structure with four sensing units in which the bottom substrate has four pairs of electrodes while the top deformable portion has a solid-state electrolyte. The application of normal and shear forces increases the contact area between the solid-state electrolyte and the electrodes. Key innovations in the sensing mechanism include the use of a paper-based solid state electrolyte, the use of 3d-printing with a combination of soft and hard polymers to construct the top portion of the sensor, and the use of deep learning to model the sensor response. The sensor can accept any combination of shear and normal forces and can measure both their magnitudes and orientation. The deep learning based sensor response model enables accurate sensor calibration while accommodating the imperfections in the stiffness distribution of the sensor. The normal and shear force sensitivities are of the order of 50 nF/N and 22 nF/N respectively, which are orders of magnitude larger than the sensitivity of a traditional capacitive force sensor.

In this paper, three dimensional spherical magnetic field coils are proposed and optimized for atomic sensors that require highly uniform magnetic field coils within a limited volume. The design objective of the uniform coil is transformed into a nonlinear optimization model with constraints, which is solved by combining with the particle swarm optimization algorithm. Compared with the traditional cylindrical tri-axial magnetic field coil system whose volume is limited by the aspect ratio of the coil structure, the three dimensional spherical coils not only effectively reduce the volume but also provide consistent magnetic field performance in the three coordinate axis directions. It is of great significance to the miniaturization of atomic sensors. The theoretical calculation shows that the uniformity of spherical coil is improved by about 2 to 3 orders of magnitude compared with the Lee-Whiting coil and the saddle coil. The measurements show that the magnetic field uniformity of our design reached $1.5\times 10^{-4}$ along the ${z}$ -axis within a range of $\pm 0.25{R}$ . The actual magnetic field distribution is basically consistent with the theory. However, due to the limited processing and experimental conditions, the actual magnetic field uniformity is 1 to 2 orders of magnitude lower than the theory.

We report an ambipolar phototransistor using the organic–inorganic hybrid perovskite, CH3NH3PbI3 [methylammonium lead iodide (MAPbI3)]. The high iconicity of MAPbI3 leads to intrinsic p-type and n-type self-doping, which enables simultaneous or selective hole and/or electron transport in a single device, depending on the bias conditions. Under white light illumination, both hole and electron current increase by four orders of magnitude and the dark characteristics recover completely and immediately after turning off the light source. In addition, the photosensitivity can be controlled by compositional ratio (MAI:PbI2) and the thickness of the MAPbI3 film. Moreover, the hole current shows higher responsivity and shorter response time (0.62 A/W and 100 ms) compared with electron current (0.20 A/W and 200 ms), resulting in respective photodetectivity values of $6.87\times 10^{15}$ and $1.33\times 10^{15}$ Jones. These photodetectivities are among the highest reported, making the phototransistors reported herein suitable for simple and cost-effective optoelectronics.

$p$ -type modulation doping of the quantum dot active region is known to improve high temperature and dynamic performance of quantum dot lasers. These improvements are critical to realizing commercially relevant quantum dot devices on silicon and are shown to enable continuous wave operation over 100°C, nearly complete insensitivity to optical feedback, and orders of magnitude improvement in device reliability relative to unintentionally doped active regions. Also described is a spectrally resolved analysis of the effect of p-modulation doping on the optical gain revealing anomalous behavior that explains the high characteristic temperatures commonly observed in literature for similar devices on native substrate.

Surface passivation is critically important to improve the leakage current and current on/off ratio in Schottky diodes and thus the overall device performance and reliability. In this work, we report the reduction of leakage current in Pt/n-GaN and Pd/n-GaN Schottky diodes by improving metal-GaN interface passivation using ultraviolet/ozone (UV/O3) plasma treatment. X-ray photoelectron spectroscopy was used to verify the improved passivation at the surface of GaN. Capacitance-voltage measurements were employed to determine the change in built-in potentials and the Schottky barrier heights of the Schottky diodes. Temperature-dependent measurements of current-voltage characteristics verified the thermionic emission carrier injection mechanisms. It was found that the leakage current in the GaN Schottky diodes was reduced by three orders of magnitude and the current on/off ratio was increased by two orders of magnitude due to the interface passivation that reduced defect states at metal-semiconductor interfaces and suppressed dislocation-induced leakage current.

It is experienced that MV XLPE cable links including heat shrink cable joints can have a high electrical conductivity compared to the XLPE cable insulation. The field grading sleeve included in the joint design is proposed to be responsible for the reduced insulation resistance and is therefore studied in this paper. New field grading sleeves are aged in the laboratory at temperatures up to 150 °C in both dry and humid conditions. The degree of ageing is determined by DSC measurements, the mechanical properties are determined by tensile strength testing, and the electric properties are characterized by time domain dielectric response measurements. The results show that after only a few days above the melting point of 104 °C the tensile strength of the material is strongly reduced. The electrical conductivity is strongly dependent on the degree of thermal ageing of the sleeve material but also the water content. The combination of significant thermal degradation and a high water content results in particularly high conductivity values. It is shown that the increase of the conductivity after ageing at 150 °C for 15 days is five orders of magnitude for wetted field grading sleeves measured at 30 °C. © 2019 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.

We report a novel magnetic field sensor based on a PT-symmetry structure with the modulation of magnetic resonators giving advantages of high sensitivity, large sensing range, and low equipment expenses. The structure has a unique band-edge mode whose wavelength is very sensitive to the external magnetic field. The band-edge mode can be used to detect magnetic fields. The sensitivity range is 240– $2.435 \times 10^{4}$ nm/Oe, which is larger than those obtained using other approaches by an average of two–six orders of magnitude. The sensing range is 1300–4500 (Oe), which is larger than those of other approaches by an average of two orders of magnitude. The proposed magnetic field sensor is very important for applications requiring extremely higher sensitivities over a wide magnetic field range

Metal–semiconductor and junction n-channel field-effect transistors (MESFETs and JFETs) have been fabricated on glass substrates using room temperature deposited amorphous zinc–tin oxide (ZTO) channel layers. Characteristics of transistors and inverter circuits are compared. Best FET devices exhibit ON-to- OFF current ratios over eight orders of magnitude, subthreshold swings as low as 250 mV/dec and field-effect mobilities of 5 cm2/Vs. Furthermore, all devices show long-term stability over a period of more than 200 days. Inverters fabricated using either MESFETs or JFETs exhibit remarkable peak gain magnitude values of 350 and voltage uncertainty levels as low as 260 mV for an operating voltage of 5 V. A Schottky diode FET logic (SDFL) approach is applied to shift the switching voltage which is a requirement for cascading of inverters for realization of ring oscillators.

Vertical Au/ZnO Schottky barrier diodes (SBDs) were fabricated on an n+ Si substrate and tested as X-ray detectors in this paper. The high-resistivity ZnO film-based SBDs had a large effective area about 0.78 cm2 and showed a notable sensitivity about 0.78 uC/Gy for X-ray illumination. The detector with linear outputs achieved an X-ray dose measurement across four orders of magnitude of the dose rate from 3.83 mGy/s to 19.00 Gy/s. The response current to switched X-ray illumination exhibited a repeatable and stable characteristic, and the response current mechanism was given and discussed. The results imply the potential of junction devices based on ZnO material for X-ray dose measurement.

The experiments on deuterium plasma-driven permeation through liquid Ga and Li were conducted in a linear plasma device VEHICLE-1. Deuterium transport parameters such as diffusivity and surface recombination coefficient for Ga and Li were measured from the experiments. By using the measured transport parameters, deuterium dynamic retentions in Ga and Li under steady-state plasma bombardment were evaluated with the DIFFUSE code. It has been found that the deuterium dynamic retention in Ga is ~five orders of magnitude lower than that in Li under present experimental conditions. After exposed to the steady-state deuterium plasma at temperatures from 78 °C to 360 °C, deuterium static retentions in liquid Ga are measured by the thermal desorption spectroscopy. It has been found that the deuterium static retentions in Ga are close to the dynamic retentions when the exposure temperatures are below 250 °C.

In this letter, we present a magnetic field sensor with a noise equivalent field of 500 nT based on a tapered fiber in a magnetic fluid (Fe3O4 nanoparticles dispersed in the deionized water). This sensitivity, which is three orders of magnitude better than the previously demonstrated tapered sensors, is achieved by biasing the fluid material with a ≈1-mT magnetic field. In addition, application of an optical modulator and an auto-balanced synchronized detector increased the sensor output signal-to-noise ratio significantly. Furthermore, a novel method is presented to employ the proposed sensor in a distributed scheme.

Laser-induced dispersion provides an all-optical means for dynamically controlling light propagation. Previous works on dispersion control with a laser beam make use of Kerr non-linearity, electromagnetic-induced transparency, and stimulated Brillouin scattering in optical fibers. Here we report, for the first time to our knowledge, optically controllable dispersion with stimulated Raman scattering in a gas-filled hollow-core optical fiber and show that flexible dispersion tuning can be achieved by varying optical pump power and wavelength as well as gas concentration and pressure in the hollow core. As an example of application, we demonstrated the use of such laser-induced dispersion for high-sensitivity hydrogen detection and achieved a normalized detection limit of 17.4 ppm/(m·W) with dynamic range over four orders of magnitude.

We present a new sensing technique exploiting light-sheet excitation of skew rays in a multimode fiber, which can be applied to enhance the sensitivity of a range of sensing mechanisms such as pump absorption. The underlying principle is that a light sheet (i.e. thin plane of light) can selectively concentrate the optimum ray group, giving rise to enhanced interaction between light and matter (e.g. fluorophores). We compared this excitation method with others in terms of attenuation of pump light through Rhodamine B. It was observed that the attenuation experienced by light-sheet skew rays can be up to one order of magnitude higher than that of collimated skew rays, and three orders of magnitude higher than that of normal-incidence rays. Refereed/Peer-reviewed

Antennas that operate in the very low frequency (LF) band and below are useful for a number of applications, including long-distance and underwater communication. When constrained in size, the antennas are electrically small and very inefficient. This has motivated the need for novel approaches to LF antenna design. Here, we present concepts for antennas that generate electromagnetic signals from mechanical motion. We first review the generated fields and efficiency of conventional magnetic and electric dipole transmitters. This is then extended to their mechanical counterparts for comparison. Our results show that the motion of magnets or electrets (the electrical analog of a magnet) can efficiently radiate electromagnetic energy when coupled to a low-loss electromechanical suspension. Mechanical antennas, with spatial dimensions on the order of a meter, can theoretically exceed the performance of conventional short dipole and coil transmitters by more than eight orders of magnitude for frequencies of 1 kHz and below. This paper is intended to lay the foundation for future development involving the implementation of efficient, small form-factor, mechanically actuated antennas.

Thermionic electron emitter, a critical component in vacuum electronic devices, usually suffers from bulky size, difficulty to integrate, and slow temporal response. Here, to overcome these problems, we fabricate and test a new miniature electron emitter: on-chip thermionic electron emitter arrays based on horizontally aligned single-walled carbon nanotubes. The devices are fabricated and integrated on a Si chip with microfabrication technologies, providing compactness as well as fast temporal response. Emitter arrays with a packing density of up to $\sim \textsf {0.4}\times 10^{7}$ emitters/cm2 and an emission density of 1.73 mA/cm2 at a bias voltage of 2.64 V are realized. The turn-on/off response times of the devices are measured to be ~150/500 ns, which are 5 orders of magnitude faster than those of their bulky counterparts. The advantages of on-chip nature, high degree of integration, and fast temporal response make the thermionic emitter arrays promising in miniature vacuum electronic devices.

This paper presents a multiscale method for the numerically efficient electromagnetic analysis of two-dimensional (2-D) photonic and electromagnetic crystals. It is based on a contour integral method and a segmented analysis of more complex structures in terms of building blocks which are models for essential components. The scattering properties of essential photonic crystal components, such as waveguide sections, bends, and junctions, can be expressed independent of the electromagnetic wave launch parts which are used for the excitation by de-embedding of the network parameters. To enable this, the launch properties are extracted by a calibration technique using several calibration standards analog to a measurement. The de-embedding can be applied both to the proposed integral method and to the reference results from other full-wave methods. The extracted scattering parameters of the components can be used in a multiscale analysis for the efficient simulation of very large 2-D photonic and microwave structures with circular inclusions as the concatenation is performed only in terms of the network parameters. The proposed approach is about one to two orders of magnitude faster than the conventional unsegmented analysis with the contour integral method and several orders of magnitude faster than the full-wave reference method.

The Naval Research Laboratory has developed a low-power, real-time displacement damage dosimeter (RT3D). RT3D consists of two components; one being the measurement electronics and the second being the actual dosimeter (GaAs diode) exposed to the radiation source. RT3D accumulates displacement damage passively (without power) and the displacement damage dose (DDD) is measured at will with measurement electronics by measuring the GaAs diode dark current at one or more forward bias voltages. The DDD is subsequently determined in real-time from a calibration curve derived from ground-based testing. The dosimeter is capable of measuring approximately three orders of magnitude in DDD. The dosage measurement range of the sensor can be modified by placing an absorber material over the sensor. Proton testing performed in situ yielded an error estimate determination to within 10% for simulated space use.

This paper presents design, fabrication, and characterization of flexible capacitive graphene oxide (GO) based humidity sensors, which can be used in many applications, such as environmental protection, civil engineering, and agriculture. They consist of interdigitated electrodes ink-jet printed on a polyimide flexible substrate and GO based sensing layer. Measurement setup for testing and characterization was developed in laboratory conditions. The dependence of the capacitance and resistance of the GO based humidity sensors on the percentage of the applied humidity is presented. The main advantage of developed GO based capacitive humidity sensors is very large variation of capacitance, almost five orders of magnitude, compared with the previously demonstrated sensors. The other advantages of the sensors are fast response-recovery time, excellent reproducibility of the measurement results, and use of cost-effective additive ink-jet technology.

[100]-tilt YBa 2 Cu 3 O 7-x bicrystal Josephson junctions (JJs) with resistances R n = (50-500) Ω and characteristic voltages I c R n (50 K) of 2.5 mV have been fabricated and their potential as classical terahertz detectors has been evaluated. The dc I-V curves of the JJs at temperatures T above 40 K have been found free of hysteresis and demonstrated high nonlinearity with the second derivatives d 2 V/dI 2 up to 10 7 -10 8 Ω/A at T = 50 K. The response ΔV(I) at the current I corresponding to the maximum of d 2 V/dI 2 has been observed in a power range of more than four orders of magnitude, and ΔV is directly proportional to the incident power P (square-law detection) at low power, then ΔV ~ P 1/2 (linear detection) at higher power. The responses ΔV(V) at low voltages V to external radiation with the frequencies from 0.05 to 3 THz have been experimentally found to be proportional to d 2 V/dI 2 (classical detection) at low frequencies and to dV/dI (Josephson detection) at high frequencies with a crossover near the low-frequency limit f l = (0.9 ± 0.3) THz of the ac Josephson effect in our JJs. Numerical simulations of such quasiclassical detector with R n = 300 Ω at T = 50 K predict the NEP-values of 5·10 -15 W/Hz 1/2 at the frequencies up to 1 THz.

We discuss the theory, design, fabrication, and testing of a three-terminal memristor based on thin-film metal oxides. The fabricated device modifies a traditional SrTiO3 thin-film memristor to include a third control terminal. The results show the device conductance is continuous over three orders of magnitude, with significant retention and endurance, and comparatively low set and reset currents. The gate allows for continuous conductance state tuning, and allows for flexible architectures compared with traditional two-terminal memristors by separating the read and write terminals.

This letter proposes a novel device structure named P-edge nMOS, in which high P+ doped belts are placed at the edges of the N+ source and drain. This structure is immune to the radiation-induced edge effects, thus, is able to improve total ionizing dose tolerance with much less area cost than enclosed layout transistors. Furthermore, P-edge nMOS is fully compatible with standard commercial technologies and can be used as a technique of radiation hardened by design. In order to evaluate the radiation tolerance of the new structure, sample transistors fabricated by the SMIC 350-nm commercial CMOS process with shallow trench isolation have been irradiated up to total doses of 2 Mrad(Si). The experimental results show that the leakage current of the P-edge nMOS is four orders of magnitude smaller than the normal nMOS device and the threshold voltage variation of the P-edge nMOS is reduced by about 90% when the dose is up to 2 Mrad(Si). The proposed P-edge nMOS can be a competitive alternative device to be used in CMOS integrated circuits for space applications.

We propose a scheme for an all-optical comparator which embeds a nonlinear fiber ring resonator in a Mach–Zehnder configuration. Such a resonator accumulates the circulating power of the light traversing the ring, so that the effective nonlinear phase shift in fiber can be significantly enhanced. Numerical results demonstrate that with appropriate choice of the parameters of the Mach–Zehnder configuration and the power of the probe light, the all-optical comparator can exhibit an excellent step-like transfer function. Simultaneously, the configuration reduces the switching threshold by 3 or more orders of magnitude to the level of milliwatt when conventional highly nonlinear fibers are adopted. In addition, our simulations show that this all-optical threshold comparator also has a multiperiodic transfer characteristic and thus may be used to construct multibit analog-to-digital convertors.

Experiments demonstrate gas breakdown within a single point defect in a 2D photonic crystal at millimeter wave frequencies (43.44 GHz) using only 1.5 W of continuous wave input power. We show that after formation of the plasma within the defect, the transmission of energy through the crystal is decreased by two to four orders of magnitude for gas pressures from 30 to 750 torr. Time domain measurements of the transmitted energy through the device show plasma formation times ranging from 800 ns at 45 torr to 180 ns at 400 torr of argon gas. Electron density of the plasma is 1018 m−3 at low pressures and up to 1020 m−3 at 750 torr.

A novel beyond-CMOS device concept, the Bilayer pseudoSpin Junction Transistor (BiSJT), is proposed. Like the previously proposed Bilayer pseudoSpin FET (BiSFET), the BiSJT is motivated by the possibility of interlayer electron–hole exciton condensation in bilayer 2-D material systems, and could provide switching energies of a few 10 s of zJ, orders of magnitude below even end-of-the-roadmap CMOS. The BiSJT is, however, current-controlled, and may allow for simpler device design, smaller device area, and more flexible gate design.

Being able to increase the sensitivity of magnetoresistive sensors, by orders of magnitude, provides a route toward challenging detection levels, and opens the way for new applications. This paper describes a novel architecture of magnetic flux concentrators to achieve an improved guiding efficiency, combining materials with different magnetic properties, and a vertical tapering. The novelty consists in the concentration of the magnetic flux kept by the entire structure in a reduced cross-sectional area within the vicinity of the spinvalve sensor. Depending on the configuration of the double-layer magnetic flux concentrators, average sensitivity gains of $\sim 90\times$ and $\sim 400\times$ were obtained. This enhanced guiding efficiency also reduced the impact of a misalignment between the device sensing direction and the applied magnetic field, since the device performance is not compromised until a misalignment angle $\theta = 45$ °. This further stabilization may arise from the vertical tapering of the magnetic flux concentrator, being consistent with 2-D finite-element simulations.

This paper models the performance and summarizes the design considerations (electrical, mechanical, and thermal) of CMOS-SOI-NEMS (CMOS Silicon on Insulator nanoelectro mechanical systems) transistors fabricated in the 130-nm technology, which perform as uncooled passive infrared (PIR) sensors. The nanmachined CMOS-SOI-NEMS transistors (dubbed TMOS) are isolated thermally by the postprocessing dry etching with high yield and uniformity, achieved at the wafer-level processing as well as the wafer-level packaging, using 8-in wafers. The TMOS transistor is an active sensor with internal gain achieving voltage, responsivity, over $10^{7}$ V/W. This responsivity is larger by approximately an order of magnitude compared to bolometers, and several orders of magnitude compared to thermopiles or pyros, which are passive devices. The TMOS operates at subthreshold, requiring very low power, of the order of microWatt. Accordingly, this uncooled IR sensor, in the low-cost CMOS-SOI technology, promises to become the standard PIR technology for mobile applications, wearables, and Internet of Things.

Acoustical imaging systems are an important kind of instrumentation for underwater investigation. Currently, angular resolutions of most existing real-time underwater 3-D imaging systems are around 1°, which cannot meet the high-quality imaging requirement in a relatively far distance. Enhancing the angular resolution of a real-time 3-D imaging system needs enlarging the aperture size of its receiving 2-D array. However, the huge number of elements is not affordable for a traditional fully sampled uniform large 2-D array with half-wavelength interelement spacing to achieve a high angular resolution. This paper proposes the concept of ultralarge ultrasparse ultra-wideband (UUU) 2-D arrays for achieving the high angular resolution of underwater 3-D acoustical imaging systems. The design method of UUU 2-D arrays is demonstrated through the example of designing an annular 2-D array with only 100 elements. The capabilities of the designed annular UUU 2-D array are evaluated, showing that it can achieve a 0.1° angular resolution and a −32 dB maximum sidelobe level. The imaging simulations of complicated targets also demonstrate that the designed annular UUU 2-D array can satisfy the requirement of high-resolution underwater 3-D acoustical imaging. The element number of the designed annular UUU 2-D array is 4 orders of magnitude lower than that of a fully sampled uniform 2-D array, which provides a viable choice for developing high-resolution real-time underwater 3-D acoustical imaging systems.

Electric cell lysis (ECL) is a promising technique to be integrated with portable lab-on-a-chip without lysing agent due to its simplicity and fast processing. ECL is usually limited by the requirements of high power/voltage and costly fabrication. In this paper, we present low-cost 3-D nano-spikes-based ECL (NSP-ECL) chips for efficient cell lysis at low power consumption. Highly ordered High-Aspect-Ratio (HAR). NSP arrays with controllable dimensions were fabricated on commercial aluminum foils through scalable and electrochemical anodization and etching. The optimized multiple pulse protocols with minimized undesirable electrochemical reactions (gas and bubble generation), common on micro parallel-plate ECL chips. Due to the scalability of fabrication process, 3-D NSPs were fabricated on small chips as well as on 4-in wafers. Phase diagram was constructed by defining critical electric field to induce cell lysis and for cell lysis saturation $\text{E}_{sat}$ to define non-ECL and ECL regions for different pulse parameters. NSP-ECL chips have achieved excellent cell lysis efficiencies $\eta _{lysis}$ (ca 100%) at low applied voltages (2 V), 2~3 orders of magnitude lower than that of conventional systems. The energy consumption of NSP-ECL chips was 0.5–2 mJ/mL, 3~9 orders of magnitude lower as compared with the other methods (5J/mL-540kJ/mL).

A graphene oxide (GO)-based sensor with differential structure was designed to detect both humidity and temperature. Two identical units have been fabricated with patterned gold electrodes on which a layer of GO was deposited by the drop-casting or spraying coating method. One unit was then covered by a layer of polydimethylsiloxane to modify its response to the temperature and humidity. Using this differential structure, the sensor shows great linearity in a temperature range from 20 °C to 60 °C and a humidity range from RH25% to RH95%. The humidity response of the two units varied for three orders of magnitude under the same temperature, which indicates a good sensitivity of the device. We have also found that the spray-coated sensor has a relatively short response and recovery times than the drop-casted one.

Surface enhanced Raman scattering has recently been proposed as a label free sensing method for diagnostic applications. Raman scattering is an excellent analysis tool because a wealth of information can be obtained using a single measurement, however the weak signal has made it unsuitable for detecting low concentrations of analytes. Using plasmonic nanostructures to create SERS substrates, the Raman signal can be amplified by several orders of magnitude, but SERS substrates have been complicated to fabricate. Here we report low-cost silicon substrates based on simple fabrication method of silver nanoparticles and silicon nanowires decorated with these nanoparticles for use as a convenient practical platform for SERS-active substrates. In addition, the placement of silver nanoparticles on silicon nanowires allowed the autoaligning of the hot spots such that low cost Raman systems with normal incident laser can be used. These substrates have the ability to detect wide range of concentrations of pyridine, as low as 10 –11 M. An enhancement factor of around 6 to 8 × 105 was observed for silver nanoparticles alone. By depositing the same nanoparticles on silicon nanowires, the enhancement factor jumped by orders of magnitude to 1011.

We propose an array of unbiased antennaless continuous wave (CW) THz photomixers made of subwavelength buried metal–semiconductor–metal (MSM) gratings with dissimilar Schottky barriers. These dissimilar metals in each unit cell are in intimate contact, and yet the maximum electric field appearing in the semiconducting material, unlike that in the planar structures, is far below its breakdown threshold. This relaxes the breakdown constraint that is normally confronted in the design of similar THz emitters with planar gratings. Besides, as compared with a similar array with subwavelength but planar MSM gratings, use of the buried MSM has increased the volume in which the carriers’ photogeneration occurs, enhancing the resultant CW THz radiation by an order of magnitude. This is also five orders of magnitude greater than the THz power that can be radiated by a similar array of the same size with diffraction-limited planar electrodes. Moreover, calculating the frequency dependence of the THz output power, the newly proposed plasmons-assisted emitters are shown to be tunable in a wide range of 0.1–3 THz. We have also numerically demonstrated that 4.5% of the 1.58 mW optical pump can efficiently be converted to the THz power at the radiation frequency of 0.5 THz.

We proposed an ultrafast accelerated retention test methodology for resistive random access memory (RRAM) using micro thermal stage (MTS). For accelerated retention test using chuck heating, the two major factors that limit the test speed are the attainable temperature range and thermal time constant. To extend these limits, we built MTS with extended temperature range (~800 °C) and short thermal time constant ( $\sim 10\mu \text{s}$ ). Using high resistance state retention failure of HfOx-based RRAM as an example, we demonstrated that the proposed methodology can reduce accelerated retention test time to

A dual-mode fiber optofluidic flowmeter with a large dynamic range of four orders of magnitude is developed. The sensing mechanism is based on the force balance on an optically trapped polystyrene microparticle. As the optical force is at piconewton level, the flowmeter is very sensitive with a lower detection limit of 10 nl/min. In the open-loop mode, the manipulation length is used as the sensing output and the flowmeter has an inverse sensitivity so that it has higher sensitivity at lower flow rate. In the closed-loop mode, the manipulation length is set constant and a feedback signal, tuning the laser power for the force balance, is used as the sensing output. The closed-loop mode is helpful for extending the upper detection limit of flow rate and also enhancing the sensitivity at higher flow rate. This paper introduces a new kind of high-performance optofluidic sensors based on optical forces.

This article provides a comprehensive review of recent advances in heterostructures of two-dimensional (2-D) layered materials for future electronic and optoelectronic applications. We also discuss the progress in capping heterostructures, where an inert 2-D material serves as a passivation layer and provides environmental stability to the relatively unstable 2-D material. Such capping of heterostructures often enhances the electronic properties (e.g., the carrier mobility) of the active 2-D layer by orders of magnitude. Finally, we elucidate the progress in large-area growth of these heterostructures using various state-of-the-art techniques.

Hydraulic fracturing is an essential way to improve the production of unconventional shale oil and gas. It is important to characterize the produced fractures using either acoustic or electromagnetic (EM) methods. Conventional EM solvers in the low-frequency range face significant challenges by such multiscale problems where the fracture width is orders of magnitude smaller than its diameters. Furthermore, the cased borehole environment is extremely difficult to simulate with conventional EM solvers due to meshing difficulties and the multiscale nature of the problem. In this paper, we develop a hybrid distorted Born approximation and 3-D mixed ordered stabilized biconjugate gradient fast Fourier transform (DBA-BCGS-FFT) method to simulate the very challenging 2-D, 2-D-axisymmetric, and 3-D hydraulic fracture models under both open and cased borehole environments. Numerical examples show that this method has orders of magnitude higher efficiency than the finite element method. The capabilities of the DBA-BCGS-FFT method for the induction tool fracture mapping are demonstrated by comparing with laboratory experimental results and other reference results.

We present a novel approach in designing high-throughput high-resolution apertureless near-field scanning probes with enhanced nanofocusing based on graphene plasmonics. Extremely localized plasmons on graphene are mingled with nanofocusing of surface plasmon polaritons to confine and steer the plasmon waves into the apex of a near-field scanning optical microscopy tip. The Fermi level, localized emission sites on graphene, and the angle of excitation play a critical role in exciting graphene surface plasmons on the lateral walls of the designed conical probes. The optimized probes feature full-width at half-maximum (FWHM) around 25 nm, which is at least two times smaller than conventional metallic plasmonic tips. The near-field electromagnetic properties of the designed probes are characterized in detail and compared to the conventional single-aperture and typical apertureless metallic plasmonic (silver and gold) probes. Over three orders of magnitude electric field enhancement compared to metallic probes on SiO2 substrate has been achieved.

We propose a novel static random access memory (SRAM) cell employing correlated material (CM) films in conjunction with the transistors to achieve higher read stability, write ability, and energy efficiency. The design of the proposed SRAM cell utilizes orders of magnitude difference in the resistance of the insulating and metallic phases of the CM to mitigate the design conflicts. By appropriately controlling the phase transitions in the CM films during SRAM operation through device–circuit codesign, we achieve 30% higher read static noise margin and 36% increase in the write margin over standard SRAM. The proposed design also leads to a 50% reduction in the leakage current due to high insulating state of the CM. This is achieved at 28% read time penalty. We also discuss the layout implications of our technique and present techniques to sustain no area overhead.

The light-induced self-written (LISW) waveguide technique is a promising candidate for the practical realization of a passive alignment between telecommunication and silicon photonic devices. While silicon is transparent to wavelengths above 1100 nm, the one-photon polymerization wavelength range is limited below 1100 nm. In this study, LISW waveguide fabrication at telecommunication wavelengths was demonstrated using a single-photon photopolymerizing resin. The LISW waveguide fabrication threshold values are lower than that of the two-photon photopolymerization system by six to seven orders of magnitude. LISW waveguides are fabricated from a single-mode fiber, a vertical-cavity surface-emitting laser, and a silicon waveguide. Using this technique, fiber-to-chip self-coupling between silicon photonic devices at telecommunication wavelengths is demonstrated. The results demonstrate the potential of the LISW technique for optical self-coupling of telecommunication and silicon photonic devices.

We report the design, fabrication, and characterization of an ultrasensitive resonant (~300–400 Hz) magnetometer with 0.67-mV/nT sensitivity. The sensor was composed of a low stress (−14 MPa) low-pressure chemical vapor deposition silicon nitride cross bridge and a neodymium magnet. External magnetic field biasing (to modify the effective Hooke’s constant), shielding, mechanical isolation, and parametric amplification and feedback were used to progressively improve the sensor performance from 1 $\mu \text{T}$ minimum detectable signal to 27 pT; an improvement of five orders of magnitude. The sensor’s average temperature sensitivity around the room temperature was 11.9 pV/pT/°C.