Bottom Film Research Articles

Enhanced terahertz absorption of quantum wells sandwiched between heavily doped contacts based on micro-cavity resonance

A novel high-efficiency microcavity structure of quantum wells sandwiched between periodic heavily Si-doped GaAs top contact gratings and bottom contact film has been proposed as the optical coupler of a terahertz quantum well photodetector (THz QWP). Similar to metal at visible light, highly doped semiconductors exhibit plasma frequencies at mid- and far-infrared wavelengths. The intersubband absorption spectra and electric field distribution of the microcavity THz QWP are calculated with the finite difference time-domain method. Our results indicate that the frequency of the surface plasmon polariton can be tuned to the microcavity resonant mode under an optimized structure and the intersubband absorption is efficiently enhanced by the microcavity structure. When the doping concentration of the contact exceeds 1018 cm−3, the intersubband absorption of the microcavity THz QWP at the response wavelength is over one order of magnitude higher than that of the standard 45° device. In addition, the angle of the incident light only influences the intensity of the absorptivity, indicating that the designed device was independent of the periodic surface structure.

Minimizing the Consumption of Stretch Film for Wrapping Cylindrical Baled Silage Using the IntelliWrap Method

HighlightsA complete mathematical model describes stretch film consumption for wrapping round bales using IntelliWrap.An algorithm is presented for optimal, in the sense of minimal, film usage based on film width selection.A solution is presented for selecting the optimal width of commercially available film.Optimal film width guarantees up to 10% savings in film usage, especially for not more than ten film layers.Abstract. The new IntelliWrap method is considered for wrapping round bales of agricultural materials using two different widths for the contact area between adjacent film strips for the bottom and upper film layers. A complete mathematical model describing the consumption of film for round bale wrapping is derived, which captures bale and film dimensions, the mechanical properties of the film as described by Poisson’s ratio and the unit deformation, the overlaps between adjacent film strips, and the numbers of bottom and upper film layers. The surface area of the film used to wrap the bale is used as a measure of film usage. To reduce film usage and protect the environment, the problem of achieving optimal, in the sense of minimal, film usage is mathematically formulated and solved. The original continuous optimization problem with a non-continuous goal function is reduced to solving two simpler integer programming tasks. An algorithm for selection of the optimal film width is proposed and numerically verified. If the common 50%, 66.7%, and 75% overlaps are used and the film width is optimal, then minimal film usage is achieved regardless of the composition of the bottom and upper film layers. In addition, the problem of choosing the best commercially available film width to guarantee minimal film usage is stated and solved. However, only near-optimal film usage is achieved for appropriately selected, commercially available film widths. Results of numerical experiments demonstrate that the relative errors for such approximations of minimal film usage do not exceed 0.1%, while inappropriate selection of the film width may result in increased film usage with almost 10% relative error, which indicates that up to 10% film cost savings can be achieved when the film width is optimally selected according to the proposed approach, especially when the number of layers is not more than ten. Keywords: Baled silage, Mathematical model, Mixed wrapping, Optimization, Stretch film consumption.

An ultra-broadband, polarization and angle-insensitive metamaterial light absorber

We propose a new ultra-broadband metamaterial absorber based on a titanium–silica–titanium sandwich structure, which is composed of a periodic array of titanium–silica elliptical nanodisks and a titanium bottom film. The absorption bandwidth reaches 1376 nm in the wavelength range from the visible to near-infrared region with the spectral absorptivity >90%. Moreover, the spectrally averaged absorption is up to 94.6%, indicating the achievement of ultra-broadband near-perfect absorption. In addition, the near-perfect absorption is polarization-independent and incident-angle insensitive. The ultra-broadband absorption mainly results from the strong plasmonic near-field coupling by the adjacent metal parts and the intrinsic material absorption in the wide wavelength range by the refractory metal. The proposed ultra-broadband metamaterial absorber could have broad application prospects in solar photovoltaic generation, infrared detection, and hot-electron devices.

Ultra-high transparent sandwich structure with a silicon dioxide passivation layer prepared on a colorless polyimide substrate for a flexible capacitive touch screen panel

Indium tin oxide (ITO)-based multilayer structures with ultrathin silver (Ag) deposition on colorless polyimide (CPI) were investigated as touch sensor electrode materials in this study. The electrical, optical, structural, and morphological properties of the ITO-based multilayer structures were compared. The figure of merit of the ITO/Ag/ITO(160)/CPI multilayer structure (bottom ITO film deposited at 160 °C), in which the bottom ITO layer was deposited at 160 °C, was calculated using Haacke's formula, and the value was found to be 63.6 × 10−3 Ω−1. Moreover, the sheet resistance and optical transmittance at 550 nm were 6.4 Ω/□ and 91.4%, respectively. Transmission electron microscopy measurements demonstrated that the continuous Ag layer had a uniform film of 10.9 nm. When an ITO/Ag/ITO(160) multilayer structure was used as a substitute for an X–Y ITO layer electrode for fabricating a flexible capacitive-type touch screen panel (FCTSP) and a low-refractive-index silicon dioxide (SiO2) layer was used as the passivation layer, the ultra-high optical transmittance of the SiO2/ITO/Ag/ITO(160) multilayer structure was measured to be 94.6% (at 550 nm), and the average optical transmittance over the visual region (400–700 nm) was measured to be 92.2%. An FCTSP with multiple touch points was successfully fabricated using an X–Y ITO/Ag/ITO(160) multilayer electrode and SiO2 passivation layer. Finally, we also derive the related theoretical formulas to fix our experimental data. Moreover, based on the theory, we can predict the optimized thickness to support the desirable ultra-high transparency of multilayer structures. This auxiliary simulation also paves an alternative route to explore the possibilities of optimized multilayer flexible devices.

Influence of Surface Conductivity on Dispersion Curves, Mode Shapes, Stress, and Potential for Lamb Waves Propagating in Piezoelectric Plate.

Lamb waves propagating in piezoelectric plate covered by thin-film electrodes with arbitrary conductivity are investigated. The structure consists of three parts, piezoelectric plate, top and bottom thin films with arbitrary conductivities, and top and bottom free space. The governing equations in each part are first solved, and then, continuous conditions are used to form the propagating matrix. Finally, the dispersion equations are obtained by boundary conditions. Calculating the dispersion equations with different conductivities, the dispersion curves in high conductivity and zero conductivity are compared. The wave mode shapes of different branches are investigated, including the distributions of mechanical displacements and stresses in the piezoelectric plate and distributions of electrical displacement and potential in both plate and free space. The relationships between frequency difference and wave mode shapes in zero and high conductivity are investigated. Furthermore, the dispersion curves of general conductivity are calculated. The attenuation of waves is compared in different branches and different conductivities. The wave mode shapes are also calculated and compared with the cases in zero and high conductivities.

Integrated metamaterial with functionalities of absorption and electromagnetically induced transparency.

A switchable metamaterial with bifunctionality of absorption and electromagnetically induced transparency is proposed based on the phase-transition characteristic of phase change material-vanadium dioxide. When vanadium dioxide is in the metallic state, an isotropic narrow absorber is obtained in the terahertz region, which consists of a top metallic cross, a middle dielectric layer, and a bottom vanadium dioxide film. By adjusting structure parameters, perfect absorption is realized at the frequency of 0.498 THz. This designed narrow absorber is insensitive to polarization and incident angle. Absorptance can still reach 75% for transverse electric polarization and transverse magnetic polarization at the incident angle of 65∘. When vanadium dioxide is in the insulating state, the top metallic cross will interact with the bottom split ring resonator, and the interaction between them will lead to the appearance of electromagnetically induced transparency. The behavior of electromagnetically induced transparency works well for transverse electric polarization and transverse magnetic polarization at the small incident angle. The designed hybrid metamaterial opens possible avenues for achieving switchable functionalities in a single device.

The Characteristics of Transparent Non-Volatile Memory Devices Employing Si-Rich SiOX as a Charge Trapping Layer and Indium-Tin-Zinc-Oxide

We fabricated the transparent non-volatile memory (NVM) of a bottom gate thin film transistor (TFT) for the integrated logic devices of display applications. The NVM TFT utilized indium–tin–zinc–oxide (ITZO) as an active channel layer and multi-oxide structure of SiO2 (blocking layer)/Si-rich SiOX (charge trapping layer)/SiOXNY (tunneling layer) as a gate insulator. The insulators were deposited using inductive coupled plasma chemical vapor deposition, and during the deposition, the trap states of the Si-rich SiOx charge trapping layer could be controlled to widen the memory window with the gas ratio (GR) of SiH4:N2O, which was confirmed by fourier transform infrared spectroscopy (FT-IR). We fabricated the metal–insulator–silicon (MIS) capacitors of the insulator structures on n-type Si substrate and demonstrated that the hysteresis capacitive curves of the MIS capacitors were a function of sweep voltage and trap density (or GR). At the GR6 (SiH4:N2O = 30:5), the MIS capacitor exhibited the widest memory window; the flat band voltage (ΔVFB) shifts of 4.45 V was obtained at the sweep voltage of ±11 V for 10 s, and it was expected to maintain ~71% of the initial value after 10 years. Using the Si-rich SiOX charge trapping layer deposited at the GR6 condition, we fabricated a bottom gate ITZO NVM TFT showing excellent drain current to gate voltage transfer characteristics. The field-effect mobility of 27.2 cm2/Vs, threshold voltage of 0.15 V, subthreshold swing of 0.17 V/dec, and on/off current ratio of 7.57 × 107 were obtained at the initial sweep of the devices. As an NVM, ΔVFB was shifted by 2.08 V in the programing mode with a positive gate voltage pulse of 11 V and 1 μs. The ΔVFB was returned to the pristine condition with a negative voltage pulse of −1 V and 1 μs under a 400–700 nm light illumination of ~10 mWcm−2 in erasing mode, when the light excites the electrons to escape from the charge trapping layer. Using this operation condition, ~90% (1.87 V) of initial ΔVFB (2.08 V) was expected to be retained over 10 years. The developed transparent NVM using Si-rich SiOx and ITZO can be a promising candidate for future display devices integrating logic devices on panels.

Ferroelectric Properties of Si Doped HfO2 Thin Films with NiSi2 As Bottom Electrode

It has been already demonstrated that the orthorhombic phase transformation of Zr or Si doped HfO2 (induced by annealing) is responsible for its ferroelectricity but the use of capping top electrodes is usually required [1-4]. Here, we show that by using NiSi2 as bottom electrode (suggesting an orthorhombic structure after annealing), moderate ferroelectric properties of Si-doped HfO2 thin films (8.7 nm in thickness) deposited on NiSi2 electrodes can be generated during post-deposition annealing (PDA). For this Si:HfO2/NiSi2 structure, the bottom and top metallic films are deposited by sputtering at room temperature while atomic-layer deposition is used for deposition of Si:HfO2 with a cycle ratio of 1:16 (SiO2:HfO2), see figs. 1-2. Annealing in argon, forming gas and oxygen atmospheres for temperatures ranging from 1000°C down to 400°C, was done on structures having NiSi2 or TiN (used as reference) as bottom electrodes in order to correlate the influence of these processing conditions to the electrical and ferroelectric properties of the resulting MIM devices. For this, leakage current, capacitance, remanent polarization and fatigue measurements with applied voltage were obtained. Moderate ferroelectric behavior was obtained for PDA samples having NiSi2 as bottom electrode in the temperature range of 750°C–500°C, see figs. 3-4. This result shows the advantage of the use of NiSi2 bottom electrode, broadening the processing window for CMOS-compatible ferroelectric materials. AcknowledgementThis research is supported by the Center of Innovation Program from Japan Science and Technology Agency, JST.

Pressure Effects on Low-Liquid-Loading Oil/Gas Flow in Slightly Upward Inclined Pipes: Flow Pattern, Pressure Gradient, and Liquid Holdup

Summary This paper studied the effects of system pressure on oil/gas low–liquid–loading flow in a slightly upward inclined pipe configuration using new experimental data acquired in a high–pressure flow loop. Flow rates are representative of the flow in wet–gas transport pipelines. Results for flow pattern observations, pressure gradient, liquid holdup, and interfacial–roughness measurements were calculated and compared to available predictive models. The experiments were carried out at three system pressures (1.48, 2.17, and 2.86 MPa) in a 0.155–m–inside diameter (ID) pipe inclined at 2° from the horizontal. Isopar™ L oil and nitrogen gas were the working fluids. Liquid superficial velocities ranged from 0.01 to 0.05 m/s, while gas superficial velocities ranged from 1.5 to 16 m/s. Measurements included pressure gradient and liquid holdup. Flow visualization and wire–mesh–sensor (WMS) data were used to identify the flow patterns. Interfacial roughness was obtained from the WMS data. Three flow patterns were observed: pseudo-slug, stratified, and annular. Pseudo-slug is characterized as an intermittent flow where the liquid does not occupy the whole pipe cross section as does a traditional slug flow. In the annular flow pattern, the bulk of the liquid was observed to flow at the pipe bottom in a stratified configuration; however, a thin liquid film covered the whole pipe circumference. In both stratified and annular flow patterns, the interface between the gas core and the bottom liquid film presented a flat shape. The superficial gas Froude number, FrSg, was found to be an important dimensionless parameter to scale the pressure effects on the measured parameters. In the pseudo-slug flow pattern, the flow is gravity–dominated. Pressure gradient is a function of FrSg and liquid superficial velocity, vSL. Liquid holdup is independent of vSL and a function of FrSg. In the stratified and annular flow patterns, the flow is friction–dominated. Both pressure gradient and liquid holdup are functions of FrSg and vSL. Interfacial–roughness measurements showed a small variation in the stratified and annular flow patterns. Model comparison produced mixed results, depending on the specific flow conditions. A relation between the measured interfacial roughness and the interfacial friction factor was proposed, and the results agreed with the existing measurements.

Hollow-petal graphene metasurface for broadband tunable THz absorption.

We propose a tunable and broadband terahertz (THz)-wave absorber based on the graphene metasurface, which consists of a layer of graphene-hollow-petal structure array and a bottom copper film separated by a 20-μm-thick lossless thermo plastic olefin polymer of amorphous structure layer. The mechanism of such a THz-wave absorber is numerically investigated and theoretically analyzed with the aid of a modified Fabry-Perot resonant model and finite element method. A large absorption efficiency of more than 90% in a frequency range of 2.66THz ∼3.46 THz was obtained up to a THz-wave incident angle as large as 50°. The absorption bandwidth and absorptivity can be tuned by changing the bias voltage of the graphene metasurface Fermi level. This work indicates that our device has potential applications with respect to tunable sensors and smart absorbers.

Terahertz Absorber With Reconfigurable Bandwidth Based on Isotropic Vanadium Dioxide Metasurfaces

The design of a broadband tunable absorber is proposed based on a thin vanadium dioxide metasurface, which is composed of a simple array of vanadium dioxide and a bottom gold film. When the conductivity of vanadium dioxide is equal to 2000 Ω -1 cm -1 , simulated absorptance exceeds 90% with 71% bandwidth from 0.47 to 0.99 THz and full width at half maximum is 98% from 0.354 to 1.036 THz with center frequency of 0.695 THz. Simulated results show that absorptance peak can be tuned from 5% to 100% when the conductivity changes continually from 10 Ω -1 cm -1 to 2000 Ω -1 cm -1 . The designed absorber may have useful applications in terahertz spectrum such as energy harvesting, thermal emitter, and sensing.

Promoting control of antiferromagnet-induced perpendicular magnetic anisotropy in magnetic multilayers: Effects of applying in-plane magnetic supporting layers

We report that antiferromagnet-induced perpendicular magnetic anisotropy (PMA) occurring in magnetic thin films can be effectively controlled by applying ultrathin in-plane magnetic supporting layers with high ferromagnetic ordering temperature through magnetic proximity effects. In a series of epitaxially grown 12-ML Ni/Co/Mn/Co/Cu(001) films, we observed that the PMA of the top 12-ML Ni/Co films and the long-range antiferromagnetic ordering of Mn film were enhanced concurrently with the establishment of ferromagnetic ordering of the bottom Co film. This clearly proves the underlying mechanism of magnetic proximity effects, and offers another degree of freedom for the control of perpendicular-based magnetic logical devices.

Fabrication of Nanopillar Crystalline ITO Thin Films with High Transmittance and IR Reflectance by RF Magnetron Sputtering.

Nanopillar crystalline indium tin oxide (ITO) thin films were deposited on soda-lime glass substrates by radio frequency (RF) magnetron sputtering under the power levels of 100 W, 150 W, 200 W and 250 W. The preparation process of thin films is divided into two steps, firstly, sputtering a very thin and granular crystalline film at the bottom, and then sputtering a nanopillar crystalline film above the bottom film. The structure, morphology, optical and electrical properties of the nanopillar crystalline ITO thin films were investigated. From X-ray diffraction (XRD) analysis, the nanopillar crystalline thin films shows (400) preferred orientation. Due to the effect of the bottom granular grains, the crystallinity of the nanopillar crystals on the upper layer was greatly improved. The nanopillar crystalline ITO thin films exhibited excellent electrical properties, enhanced visible light transmittance and a highly infrared reflectivity in the mid-infrared region. It is noted that the thin film deposited at 200 W showed the best combination of optical and electrical performance, with resistivity of 1.44 × 10−4 Ω cm, average transmittance of 88.49% (with a film thickness of 1031 nm) and IR reflectivity reaching 89.18%.

High‐Performance Pressure Sensors Based on 3D Microstructure Fabricated by a Facile Transfer Technology

AbstractIn this paper, a high‐performance pressure sensor that imitates the sensing functions of human skin is proposed. A rough poly(3,4‐ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) film transferred from abrasive paper acts as the sensing layer, while silver nanowires deposited on the bottom Ecoflex film with a 3D microstructure serve as the electrodes. Because of the bionic hierarchical structure, the resulting sensor exhibits a high pressure sensitivity of 6.13 kPa−1, low limit of detection (20 Pa), low operating voltage (0.1 V), and broad sensing range (up to 90 kPa). Furthermore, as the sensor is ultrathin, ultraflexible, and stretchable, it can easily conform to the uneven surface of human skin to allow monitoring of physical signals from the human body or detect the tactile stimulation of objects. In addition, a sensor array consisting of 4 × 4 pixels is assembled to realize the precise mapping of spatial pressure distribution. By virtue of its superior performance and low‐cost fabrication, the proposed pressure sensor may potentially be applied to next‐generation wearable devices such as e‐skin, soft robotics, and human–machine interaction systems.

Complementary Resistive Switching Using Metal-Ferroelectric-Metal Tunnel Junctions.

Complementary resistive switching (CRS) devices are receiving attention because they can potentially solve the current-sneak and current-leakage problems of memory arrays based on resistive switching (RS) elements. It is shown here that a simple anti-serial connection of two ferroelectric tunnel junctions, based on BaTiO3 , with symmetric top metallic electrodes and a common, floating bottom nanometric film electrode, constitute a CRS memory element. It allows nonvolatile storage of binary states ("1" = "HRS+LRS" and "0" = "LRS+HRS"), where HRS (LRS) indicate the high (low) resistance state of each ferroelectric tunnel junction. Remarkably, these states have an identical and large resistance in the remanent state, characteristic of CRS. Here, protocols for writing information are reported and it is shown that non-destructive or destructive reading schemes can be chosen by selecting the appropriate reading voltage amplitude. Moreover, this dual-tunnel device has a significantly lower power consumption than a single ferroelectric tunnel junction to perform writing/reading functions, as is experimentally demonstrated. These findings illustrate that the recent impressive development of ferroelectric tunnel junctions can be further exploited to contribute to solving critical bottlenecks in data storage and logic functions implemented using RS elements.

Performance optimization of bi-layer solar steam generation system through tuning porosity of bottom layer

In recent years, solar steam generation has attracted many attentions due to its potential applications in desalination, etc. In the present work, a bi-layer solar steam generation system is prepared by daubing carbon particles on the sintered sawdust film, which possesses an advantage of adjustable porosities compared to widely used wood. Then, the influence of the porosity on the evaporation performance is explored. The experimental result indicates that: the porosity could significantly affect the water transportation in the film, and the water diffusivity increases almost linearly with the increase of the porosity. The evaporation efficiency increases with the increasing porosity, until the porosity reaches about 0.52 then decrease slowly. The positive effect of the increased water diffusivity and the negative effect of the increased thermal conductivity of the bottom film layer determine that the porosity of 0.52 is optimal for improving the evaporation efficiency. Under a solar light power of 1 kW·m−2, the optimal porosity gives an evaporation efficiency of 77.64%, which is comparable to the best performance of bi-layer systems reported in previous works. The conduction of heat through the bottom layer to the bulk water and the convection heat loss on the top surface contribute 83% to the total heat losses in the system, suggesting that the energy losses of these two modes should be further reduced in the future applications. Considering the accessible materials, easy preparation, low cost and high efficiency, we conclude that the 0.52-porosity system is suitable for being used as an efficient solar steam generation device.

Model-Based Analysis of Stretch Film Consumption for Wrapping Cylindrical Baled Silage Using Combined 3D Method

Abstract. A combined method for wrapping round (i.e., cylindrical) bales of agricultural materials based on biaxial rotation of the film applicators is considered in this study. A complete mathematical model is derived describing the consumption of the film used to wrap the bales that can be applied for film consumption estimation and design purposes. The bale and film dimensions, mechanical properties of the stretch film described by Poisson ratio and unit deformation, dimensionless relative overlap ratios determining the width of the contact area between adjacent film strips, and the assumed number of nominal film layers are taken into account. There is a need for good understanding of the influence of the wrapping process parameters on film consumption so that this method can be applied with lower cost and less damage to the environment. Based on the derived model, insight is obtained into the influence of the film width and wrapping parameters on film consumption when the combined method is used. Robustness on disturbances of the wrapping process, which lead to parameter uncertainty, is examined, and a simple algorithm for robust design of the overlaps of the bottom film layers is developed. The alternative method for wrapping round bales is the conventional method used by bale wrappers with a rotating table or with rotating arms. In this study, film consumption is compared between the combined and conventional wrapping methods. The combined wrapping method may offer substantial advantages in reduced film use compared with the conventional method. The potential reduction in film usage depends on the bale, film, and wrapping parameters. Without the proper choice of parameters, film consumption may be unjustifiably high. The model-based necessary and sufficient conditions for film usage reduction are obtained under typical assumptions concerning the bale and film parameters as well as the wrapping process parameters. No specific assumptions are made concerning the assumed number of film layers. The results concerning film usage reduction are written in the form of mathematical inequalities in terms of film, bale, and wrapping parameters. The stated conditions are useful for film consumption analysis and provide easy-to-use tools for analytical and numerical design of bale wrapping processes. A fast scheme is proposed for determining if the considered film parameters, together with the assumed number of film layers, could result in reduced film usage. For the algorithms, the executable and readable source codes are written in Matlab. Model-based simulations provide valuable insight into the underlying processes of film consumption and are shown to be useful for wrapping process design. To ensure a fair comparison, four to ten film layers are considered. Keywords: Baled silage, Film usage reduction, Mathematical models, Robustness, Stretch-wrap film consumption.

Toward calibration-free wall shear stress measurement using a dual hot-film sensor and Kelvin bridges

Combined heat transfer and wall shear stress measurements on the inner wall of a fully developed turbulent air flow in a round pipe were presented in this paper. The heat transfer was measured using a flush-mounted dual hot-film sensor composed of a non-electric conductive membrane sandwiched in between two thin nickel films. Each of the two films was installed in a branch of a separate Kelvin bridge, and operated at a same temperature; the bottom film served as an active heat insulator so that the Joule heat from the upper film transferred only to the air. Both theoretical analysis and measurements indicated for , where was the averaged Nusselt number and was the Péclet number. A calibration-free technique for wall shear stress measurement based only on measuring the Joule heat flux was found to be feasible, providing the Péclet number was in the range of 300–2500 and the film temperature was sufficiently large.

Graphene-assisted all-optical tunable Mach–Zehnder interferometer based on microfiber

We experimentally demonstrate a compact all-optical tunable Mach–Zehnder interferometer (MZI) based on microfiber. The graphene-assisted sandwich structure (GASS) integrated on the microfiber is adopted to form the all-optical tunable structure. The effective footprint of the fabricated device is about 7.31×8.66 mm2 which is much more compact than other reported all-optical tunable MZIs based on fiber system. An out-fiber 1535 nm continuous-wave pump light is employed to irradiate the GASS vertically, which can produce the strong interaction of light-graphene. As a result, the device’s response spectrum occurs red-shift due to the graphene’s photothermal effect. Compared with the microfiber MZI with only the bottom graphene film, the tuning efficiency of the microfiber MZI with GASS is improved by 6 times, which is about 0.856 pm/mW. Meanwhile, the red-shift range can exceed one free spectral range (FSR) that means the resonant wavelength can be tuned to arbitrary wavelength in the range of the transparent window. This microfiber MZI with GASS featured with wavelength tunability, all-in-fiber, compact size, easy fabrication, and simple packaging is expected for the fabricated device to be used as all-optical modulator, tunable optical filter and optical switch, etc.

Electrode-Shared Differential Configuration for Pressure Sensor Made of Carbon Nanotube-Filled Silicone Rubber Composites

To develop the differential pressure sensor made of carbon nanotube-filled silicone rubber composites with a simplified structure, an electrode-shared differential configuration is designed. The configuration includes the top and bottom sandwich layers. The top sandwich layer is composed of the top film, the intermediate film, and the composite film with low carbon nanotube content between them. The bottom sandwich layer is composed of the intermediate film, the bottom film, and the composite film with high carbon nanotube content between them. The electrode in the intermediate film is shared by the top and bottom sandwich layers, which can make the sensor probe more concise. The electrical resistance of the composite film with high/low carbon nanotube content increases/decreases with the increase of the pressure, and increases with the increase of the temperature. The top and bottom sandwich layers are connected to the neighboring arms of an electrical bridge to construct a differential system. The experiments verify the feasibility of using the electrode-shared configuration to construct the differential piezoresistive sensor made of the composite to decrease the temperature-induced drift and increase the sensitivity.