Search

Simultaneously and independently measuring two-dimensional (2D) displacement, one-dimensional (1D) for out-of-plane measurement and 1D for in-plane measurement, is important for practical applications. Although extrinsic fiber Fabry-Perot interferometers (EFPIs) have been reported for highly precise out-of-plane displacement measurements for many years, simultaneous measurement of 2D displacement with submicron accuracy has not been realized by a monolithic EFPI as far as we know. In this paper, a monolithic dual-cavity EFPI to realize 2D displacement measurement of a target is reported. By quantitatively analyzing and experimentally calibrating the linear dependences of the in-plane displacement sensitivity and interception on the cavity length, the effect of out-of-plane displacement on the in-plane displacement measurement is removed, which is the basis of the 2D displacement detection. 2D random movement detection and the repeatability of the system are investigated experimentally. Within the range of 10m for in-plane displacement, and 352m-358m for cavity length, demodulation errors better than 96nm are achieved. The 2D displacement measurement system based on the dual-cavity EFPI with the advantages of noncontact, high accuracy and compact size is promising to be applied in the 2D acceleration measurement, 2D rotor vibration measurement, 2D precise positioning in semiconductor manufacture, thermal expansion coefficient measurement, and so on.

Stable and low contact resistance is the basic requirement of each connector in electrical contact. There are many factors that affect contact resistance and investigated by many previous studies. In this work, the effect of wear debris to electrical contact endurance at different relative humidity is studied by fretting test. The contact resistance evolution curve at different relative humidity indicates that the wear debris is more effective to electrical contact resistance. The composition of the wear debris is analyzed by x-ray photoelectric spectroscopy. It is clearly revealed that wear debris give a sharp rise to contact resistance. In addition, measured results illuminated that the contact resistance is greatly reduced with the wear debris washed. Higher relative humidity can restrain the generation of debris to a certain extent. Physical model of debris formation is established to evaluate ultimate lifetime of contactor.

The reduction of temperature effect is vitally important for high precision sensors. This paper introduces the theoretical analysis and experimental verification of an in-situ compensation method on the temperature coefficient of the scale factor for a single-axis electromagnetic force-balance feedback MEMS accelerometer. A micro thermistor, fabricated together with the MEMS accelerometer, is integrated to in-situ sense the temperature variation of the accelerometer. The thermistor is connected to the voltage-to-current resistance in series, which compensates the variation of the scale factor of the accelerometer that is influenced by temperature variation. The experimental results reveal that the temperature coefficient of the scale factor of the compensated accelerometer is within 6 ppm/°C for the temperature range from 25°C to 50°C, which is reduced by 68 times compared with the uncompensated accelerometer. Benefiting from the compatible fabrication process and the in-situ compensation, the proposed method is promising to be low-cost and high-efficiency.

The NFDI4Ing Conference 2022 took place online on 26 and 27 October2022. The authors would like to thank the Federal Government and the Heads of Government of the Länder, as well as the Joint Science Conference (GWK), for their funding and support within the framework of the NFDI4Ing consortium. Funded by the German Research Foundation (DFG) - project number 442146713. If not stated otherwise within the respective document, the files go by CC-BY 4.0 license. Please refer to the license comments in the resprective slide decks.

This work presents a novel gated- diode SCR-incorporated BJT (SIB) structure for ESD protection purpose. A gated diode built in the SIB structure modulates reverse-biased P+ / N-well diode for better junction breakdown control. This device could achieve high TLP second breakdown current /ESD threshold close to that of an SCR, very high holding voltage, and reduced trigger voltage, as well as excellent latchup immunity.

The effect of tempering process on the microstructure and properties of low alloyed cast steel was studied. The results show that tempered at (200~400)°C, the M/A island of the granular bainite decomposes and carbide precipitates. When the tempering temperature rises to (500~600)°C, the M/A island is completely decomposed, and the carbide aggregates and gradually spheroidizes. With the increasing of tempering temperature, the tensile strength increases first and then decreases, elongation and impact energy show a trend of increasing at first, then decreasing and then increasing. The tempering brittleness occurs at 400°C.

Photochromic materials have received extensive attention from scientific researchers due to their novel uses. Though the related mechanism research is getting deeper, the current material preparations are complex and expensive. In this paper, we propose prepare a linen/polyethyleneimine/sodium decadecanate photochromic fabric via layer-by-layer self-assembly method. By building an electron transfer photochromic system on linen fabrics, the fabricated fabric not only presents outstanding reversible color-changing properties (quick color-changes speed, apparently color difference) under UV light (365 nm), but also shows excellent delicate patterns and color preservation ability in visible light environment, which endow it with great potential for application in intelligent devices and UV light detectors. Additionally, the advantageous features of good fatigue resistance (more than 15 times), light weight, comfortable feeling, low-cost and non-toxic, allow this material to be a good candidate in many applied fields.

Photochromic materials have drawn growing interesting due to their capability of interconversion under the action of external optical stimulation, allowing diverse potential applications. Herein, we proposed a novel method of preparing photochromic cotton fabric coated by combined l-(2-hydroxyethyl)-3,3-dimethyl-6-nitrospiro [l(2H)-benzopyran-2,2-indoline] terminated waterborne polyurethane. The synthesized photochromic compounds 1-(2-hydroxyethyl)-3,3-dimethyl-6-nitrospiro[1(2H)-benzopyran-2,2-indoline] (SP-OH), were characterized by FTIR spectra, 1H NMR and ultraviolet (UV) spectrum. The as-prepared spiropyran-terminated water polyurethane (SP-OH/WPU) was characterized via FTIR spectra, ultraviolet (UV) spectrum, SEM and size analysis. The photochromic cotton fabric was featured via FTIR spectra, ultraviolet (UV) spectrum and SEM. In addition, the photochromic properties, thermal stability of as-prepared cotton fabric was tested. The results showed that the photochromic compounds and SP-OH/WPU have been successfully synthesized and the resultant cotton fabric possesses excellent and durable photochromic properties, including noticeable and quick color alteration under UV radiation and fast recovery when exposed to green light. Furthermore, the excellent thermal stability ensured it undergo harsh service environment, which indicated that it is a good candidate for photochromic textile.

In electrical discharge machining (EDM), gap control is the key to stable processing; the discharge gap plays a significant role in EDM. To determine the influence of the discharge gap on material removal and melt pool movement, which are two fundamental issues in EDM, high-speed photography and molecular dynamics (MD) simulations were used to study the discharge process. Research results demonstrate that the discharge gap has a significant influence on material removal during the discharge process. A smaller gap width produces more and larger removed materials. The influence mechanism of the gap width on material removal is explained as follows. A smaller gap width produces discharge plasma with a smaller diameter and greater heat flux. Discharge with a greater heat flux generates more material removed during the discharge process. In addition, a smaller gap width and greater heat flux produce a stronger interaction of metal vapor jets, generating a stronger shear force acting on the melt pool. The discharge gap also influences the movement of the melt pool and the final topography of the discharge crater through external pressure acting on the melt pool. Smaller gap width produces greater external pressure acting on the melt pool, generating a bowl-shaped melt pool and a discharge crater with a depression in the center and a bulge around the edge. A larger gap width produces less external pressure acting on the melt pool, generating a flat melt pool and a discharge crater with swelling in the center and a depression around the edge.

This study focuses on the impact-sliding wear behaviour of CrN and WC/C tool protection coatings against Si3N4 ceramic material using a self-developed impact-sliding device. The wear mechanisms and...

In this paper, we proposed to prepare a spiropyran (SP)-based photochromic cotton fabric with high tri-stimulus response by thiol-ene click chemistry, which has excellent photochromic properties, good durability, and can quickly return to its original state under three different stimulations. The SP target monomer with ene group in the side chain was synthesized, and the cotton fabric was subjected to thiol modification by using 3-mercaptopropyltriethoxysilane. The SP molecule was grafted to the modified cotton fabric by covalent bonding, therefore effectively enhanced its durability in practical daily use. The results of FTIR, NMR, Raman and UV spectra confirmed the chemical composition. SEM images and energy-dispersive X-ray spectroscopy mapping spectra verified the grafting between this SP-based dye and modified cotton fabrics. The test data of color characteristic values indicated that the fabric undergoes significant color changes with fast photochromic response, high fatigue resistance, and maintains impressive reusability after experiencing 20 reversible cycles. The photochromic mechanism of cotton fabrics was attributed to the cleavage of C–O bond in the molecular structure of SP under ultraviolet (UV) irradiation. In addition, the properties related to practical applications including washing fastness and UV resistance have also been studied, proving its great potential in wearable and flexible textile-based sensors.

In this paper, quaternary ammonium chitosan (HTCC) was firstly prepared by chitosan (CS) and then electrospun with PVA to produce HTCC/PVA composite nanofiber membranes. CS and HTCC were characterized by Fourier transform infrared spectroscopy and transmission electron microscopy. SEM images depicted that the obtained HTCC/PVA composite nanofiber membranes had uniform porous structure. EDS mapping showed that the HTCC was homogenously dispersed in HTCC/PVA nanofiber membrane. TG and DTG analysis demonstrated good thermal stability because of the strong intermolecular hydrogen bonds between HTCC and PVA molecules. BET test was also conducted, and the porosity was about 125 nm. The maximum removal rates of PM10, PM2.5, and PM1.0 were about 92%, 86%, and 82%, respectively, indicating a good filtering effect when used as air purification material. More importantly, when the ratio of PVA–HTCC was 6:4, the antibacterial rate of Escherichia coli and Staphylococcus aureus was both over 99%. It shows that it has excellent antimicrobial properties. So the experimental results achieve our expected goals.

In this paper, a simple method has been developed to fabricate flexible fiber materials with excellent visible light response. Firstly, polydopamine (PDA) layer was deposited on the cotton fibers to functionize cotton fibers. Then, a uniformly dense layer of silver and tungsten trioxide nanoparticles was obtained on cotton fabric by reduction of PDA. The deposition of PDA provided a media for the Ag–WO3 photocatalyst to be loaded with good adhension. The results showed that the prepared cotton (C)-PDA–Ag–WO3(c) composite photocatalytic material exhibited excellent photocatalytic performance with 98% degradation efficiency of RB-19 dye solution within 180 min under visible light irradiation. Moreover, the degradation rate constants were 52.43 ×, 35.73 ×, 12.01 × and 3.77 × higher than those of raw cotton, C-PDA, C-PDA-Ag and C-PDA-Ag–WO3(a), respectively. The free radical trapping experiments showed that h+, ·OH and ·O2− were important active species in the photocatalytic process. Based on the characterizations of the system, the possible photocatalytic reaction mechanism of the C-PDA-Ag–WO3(c) composite photocatalytic material was proposed. This paper provided a new perspective for the preparation of high catalytic performance visible light responsive flexible fiber materials applied in the degradation of dye wastewater.

An in-plane displacement sensor based on an asymmetric extrinsic fiber Fabry–Perot interferometer (EFPI) is proposed and demonstrated. The asymmetric EFPI composed of a step-shaped external reflector and a cleaved fiber end face can be equivalent to two parallel FPIs with slightly different cavity lengths. By calculating the peak intensity difference of the two FPIs, the in-plane displacement can be demodulated with enhanced sensitivity and suppressed common mode noise. Both theoretical analyses and experimental results show that the sensitivity and the linear range of the in-plane displacement sensor are dependent on the cavity length. A displacement resolution of 5 nm and a linear range of ± 7 µ m under the cavity length of 250 µm are achieved in the experiment. The proposed in-plane displacement sensor with a nanometric resolution and compact size can be widely used in the fields of metrology, accelerometers, and semiconductor manufacture.

For monitoring the crystal size distribution (CSD) during L-glutamic acid (LGA) crystallization process, a deep-learning image analysis method is proposed based on the U-net network. The proposed method consists of crystal image preprocessing, crystal image segmentation, and CSD measurement. To cope with the negative influence on image analysis from continuous stirring of solution and particle motion in a crystallizer, the U-net network is adopted to perform deep learning for crystal image segmentation, with no need to prepare a large amount of training samples of real crystal images. Moreover, this approach could be implemented in real time for analysis of in-situ captured microscopic images, thus facilitating on-line measurement of CSD. Consequently, a log-normal distribution model is established for effectively depicting the one-dimensional (i.e. length) distribution of β-form LGA crystals during crystallization. A numerical example and experimental study on the cooling crystallization process of β-form LGA are shown to demonstrate the effectiveness the proposed method.

In this paper, new type Cu nanoaggregates (Cu NAs) were designed, and the Cu-Cu bonding by Cu NAs was investigated. The Cu NAs were obtained by agglomeration of the synthesized 5 nm Cu nanoparticles (Cu NPs). Compared to ultra-small Cu NPs, the collection difficulties were effectively solved and the antioxidation properties were also enhanced by the formation of Cu NAs. After sintering at 250 °C for 60 min, the Cu NAs film achieved a low electrical resistivity of 4.1 μΩ cm, which is only 2.5 times larger than that of bulk Cu. A high strength Cu-Cu bonding joint of 25.36 MPa can also be achieved via sintering of Cu NAs at 250 °C under a low bonding pressure of 1.08 MPa. After characterizations of Cu-Cu bonding interfaces and fracture structures of bonded joints, the Cu-Cu interconnection was demonstrated to be tightly contacted, sufficiently diffused and with high purity. In addition, a sintering and bonding mechanism by Cu NAs were proposed, explaining the key role played by ultra-small Cu NPs on the shell layer of Cu NAs. According to the advantages, Cu NAs are expected to be ideal substitutes to traditional solders, which have a huge application prospect in electronics packaging.

This paper reports a newly developed chip-level micro-electromechanical system (MEMS) accelerometer for tilt sensing based on differential array area-change capacitive displacement transducer and through-silicon-wafer etching process. The proposed MEMS accelerometer consists of a silicon-based acceleration-sensitive spring-mass structure, a upper glass cover plate and an universal capacitive readout application specific integrated circuit (ASIC) die, which is used to apply differential driving signals and pickup capacitance change due to area-variation under in-plane motion. The MEMS accelerometer has a linear measurement range of ±30° with a scale factor of 33.6 mV/°. The tilt measurement resolution of the MEMS accelerometer is evaluated by the modified Allan deviation with the results showing that an angle resolution of 0.003° at an integral time of 3 seconds. Compared with the commercial MEMS tilt sensors, the proposed MEMS accelerometer in this work has a larger full measurement range and a larger bandwidth but a little bit poor linearity. Hence, it is believed that the proposed chip-level MEMS accelerometer is promising to be a high-resolution tilt sensor with a lower power consumption and smaller volume.

Photochromic fabric can change color when exposed to ultraviolet (UV) light and reversibly restore to its original color after the light disappears. As a kind of photochromic fabric, good stability and durable properties are necessary. In this study, a spirooxazine material with photochromic properties, 9′-(2-bromo-2-methylethoxycarbonyl)-1,3,3-trimethyl-spiro[2H-indole-2,3′-[3H]naphtha[2,1-b][1,4]oxazine], was synthesized and applied to wool fabric with chemical bonding. Tris (2-carboxyethyl) phosphine (TCEP) was firstly utilized as a reducing agent to generate thiol groups on the wool fabric. Then, these thiol groups will react with -Br groups of the spirooxazine via thiol-halogen click chemistry. The synthesized photochromic materials were characterized by FTIR, 1H NMR and UV, and the as-prepared wool fabrics were characterized by FTIR and SEM. The results indicated that the photochromic materials have been successfully synthesized and the treated wool fabric has excellent photochromic properties, quick fading time and proper fatigue resistance while possessing good washing fastness and felting shrinkage performance.

Photochromic materials have great potential in various novel optoelectronic devices such as adaptive regulation, smart detection, information storage, and camouflage anti-counterfeiting displays. However, the problems of high sensitivity and not to be influenced by external factors are urgent to be solved. Here, we have successfully prepared smart photochromic fabrics for stimulus-responsive applications with high-sensitive spiropyran (SP) and a phase change material of butyl stearate as core materials and encapsulated by a highly translucent poly(methyl methacrylate) (PMMA) shell. And then, they are coated on the fabrics with water-based polyurethane (WPU) by a facile method of screen printing. The preparation of photochromic materials as the form of microcapusles aims at reducing external factors’ disturb and achieving a rapid response when in use. The phase change material of microcapusles acts as a thermal regulation effect on the whole system, providing energy storage and temperature regulation. The resultant reversible photochromic fabrics prepared by this method has the potential applications of tangible information storage (QR codes), anti-counterfeit printing and rewritable patterns due to their fast response and reusability under UV light.

Chlorine dioxide (ClO2) has proven its efficiency as a fumigant toward bacteria and viruses. However, it still has challenges on its portability and simplicity of ClO2 generation to meet the demand for disinfection in public and medical sectors. In this study, ClO2 stripping process via a rotating packed bed (RPB) from the commercial ClO2 solution was developed to a non-chemical-reaction ClO2 generation for air sterilization in a hospital. The ClO2 stripping efficiency (η) and the volumetric liquid mass-transfer coefficient (KLa) were examined under various operating variables, such as initial liquid concentration (CLi), rotational speed (ω), gas-to-liquid flow rate ratio (QG/QL), and liquid flow rate (QL). The results indicated that the gaseous ClO2 can be rapidly and continuously generated via stripping using RPB with η varied above 97% in the certain range of CLi (100–2000 mg/L) and QL (0.04–0.250 L/min). The overall KLa depends on the change of QL and ω, varied from 0.009 s−1 to 0.027 s−1. The output concentration of gaseous ClO2 (CG) can be adjusted from around 10 ppm to over 1000 ppm based on the established prediction model and controlling CLi, QL, QG, and ω. The results of the on-site disinfection test in the Mycobacterium Tuberculosis Laboratory in a hospital have shown effective elimination of all sites of E. coli and 2 of 5 sites of G. stearothermophilus with a CT value at the gas monitoring point of 642 ppm-h and humidity of 81%.

Photochromic materials with reversible optical properties induced by light have always been a research hotspot in the field of optoelectronics. In this work, a novel type of smart photochromic fabric is manufactured by covalent bonding of 3-mercaptopropyltrimethoxysilane (MPTMS) modified cotton fabric and spirooxazine (SO). Based on the established thiol-ene click chemistry principle, the dynamic control of the optical behavior of cotton fabric is realized. The photochromic fabric can change from colorless to blue with a fast light response speed under UV irradiation while presenting good fine images. After 20 reversible color-changing cycles, it still possesses photochromic properties and reusability, which means that the prepared photochromic fabric has great value in smart devices and light detection. Besides, the practical application in the field of optical information storage and information security encryption has been proved via the development of a Quick Response (QR) code security system.

Large superhydrophobic polytetrafluoroethylene (PTFE) films, with good durability, were successfully prepared by a facile, low cost, environmentally friendly templating method, using a PTFE emulsion. For the first time, commercially available rough glass was employed as a reusable template. The results show that both the microstructure of the glass template and the concentration of the PTFE emulsion play important roles in the superhydrophobicity of the films. Commercially available, acid-etched, rough glass is found to be an ideal template for such films, the superhydrophobicity increasing with decreasing emulsion concentration. Abrasive wear testing shows that superhydrophobic PTFE film, prepared under an optimal concentration of 5 wt% PTFE emulsion, has good abrasion resistance. Moreover, the results show that this method is suitable for the large-scale preparation of superhydrophobic PTFE films. Copyright © 2017 John Wiley & Sons, Ltd.

It is necessary to develop NO2 gas sensors as NO2 is a pollutant. While, different from the reducing gases, oxidizing gas NO2 will put up a complicated sensing process. Density functional theory (DFT) calculations are necessary to be performed to understand NO2-sensing mechanisms at the atomic level. In this study we introduce NO2 to SnO2 (110) surface with oxygen species pre-adsorbed. The results show that NO2 sensing mechanism of SnO2 surface strongly depends on the concentration of oxygen in the ambient atmosphere (usually, no effects of temperature and pressure are considered). The direct interactions between NO2 molecule and SnO2 sub-reduced surface (with two rows of fold-coordinated bridging oxygens removed) for very low oxygen concentrations show that, NO2 gas molecules interact directly with Sn instead of reacting with oxygen species, resulting in an increase in resistance of SnO2. We investigate gas-sensing processes of interaction between NO2 molecule and SnO2 surface with pre-adsorbed oxygen species for the case of considerable high oxygen concentrations. Adsorbed molecular oxygen ions compete with adsorbing NO2 molecules for available surface sites and electrons from the SnO2. As the availability of oxygen ions on the SnO2 surface increasing, the interaction between NO2 and adsorbed oxygen species give rise to a reducing interaction, which brings a decrease in resistance of SnO2.

Capacitive MEMS accelerometers with area‐variable periodic‐electrode displacementtransducers found wide applications in disaster monitoring, resource exploration and inertialnavigation. The bonding‐induced warpage, due to the difference in the coefficients of thermalexpansion of the bonded slices, has a negative influence on the precise control of the interelectrodespacing that is essential to the sensitivity of accelerometers. In this work, we propose the theory,simulation and experiment of a method that can alleviate both the stress and the warpage byapplying different bonding temperature on the bonded slices. A quasi‐zero warpage is achievedexperimentally, proving the feasibility of the method. As a benefit of the flat surface, the spacing ofthe capacitive displacement transducer can be precisely controlled, improving the self‐noise of theaccelerometer to 6 ng/&radic, Hz @0.07 Hz, which is about two times lower than that of the accelerometerusing a uniform‐temperature bonding process.

Fe60 alloy surface coating was prepared on Q345 by plasma surfacing. The hardness and wear resistance of surfacing coating were tested by Rockwell Hardness Tester and dynamic load abrasive abrasion Tester. The microstructure of surfacing coating was studied by Optical Microscopy. The Influence of the surfacing current on hardness, microstructure and wear resistance were investigated.The results showed that, the samples prepared by 140 A exhibited excellent wear resistance, meanwhile many equiaxed grains were observed to distribute uniformly in the samples.

In this work, the electrostatic discharge (ESD) protection of Schottky diode with fluorine-based plasma treatment is proven by transmission-line pulse (TLP) measurement. And the low-frequency noise (LFN) is used to determine the activation energy (E a ) of a GaN Schottky diode with plasma treatment. This experiment compares the Schottky diode with CF 4 and CHF 3 plasma treatment, respectively with a standard Schottky diode to determine the characteristics and to assess the low-frequency noise and the ESD protection ability.

The development of effective and low-cost techniques to purify textile wastewater has received intensive attention, but the applicability and practicality of many methods still remain challenging. Solar-driven interfacial water evaporation is a promising method and herein, a novel MXene/Carbon nanotubes/Cotton fabric was fabricated via layer-by-layer assembly to be used as solar steam generation for textile wastewater purification. Benefiting from the strong interfacial interactions, the composite fabric exhibited robust optical absorption, light-to-thermal conversion, and water transport properties. The evaporation rate reaches 1.35 kg m−2 for water and > 1.16 kg m−2h−1 for textile wastewater under one sun illumination, which is superior to those fabric-based materials in reported literature. The concentrations of organic–inorganic contaminants in condensed freshwater can be well reduced, which is always ignored but important to actual application. Furthermore, the reusability test and outdoor experiment were performed to demonstrate the photothermal properties when applied in practical situation. In sum, the results demonstrated that high-efficiency and durable properties coupled with simple preparation process make this composite material a potential candidate for wastewater purification via solar-evaporation.

Materials with reversible optical properties under light irradiation have great potential application in various optoelectronic fields. Particularly, photochromic materials have received extensive attention in many fields. Herein, a novel composite photochromic fabric was fabricated via Layer-by-Layer self-assembling of phosphomolybdic acid (PMoA) and polyacrylamide (PAM). Based on the established electron transfer photochromic system, the dynamic manipulation of photochromic behavior of the cotton fabric was achieved with outstanding fine high-resolution image under the visible light irradiation. The prepared fabric can change from colorless to blue rapidly (within 5 min) under UV light and maintain excellent reusability photochromic performance after more than 20 reversible color changing cycles, implying its great potential applications in the field of intelligent devices and UV detection in sunlight. Moreover, we constructed fabric weaving and developed a Quick Response (QR) code security identification to prove the practical application of the prepared photochromic fabric in the fields of wearable, optical information storage and information security encryption.

A flexible and lightweight solar ultraviolet (UV) detector compatible with cotton fabric is prepared by simple hydrogen bonding self-assembly of polyacrylic acid (PAA)and sodium deca-tungstate (SDT). Based on photochromism, the solar UV detector with good detection capabilities and the detection effect are obtained. The as-designed solar UV-induced electron transfer process imparts the detector quick response and visual color changes. The detector was tested on the spot in direct solar light and simulated solar light, which proved its outstanding performance as a flexible, wearable and visualized UV detector. Furthermore, the influence of solar doses and on-off cycle stability were studied. Therefore, the detection device fabricated can be used to indicate the intensity of UV lights by sensitive color changes, which provides a feasible idea for the preparation of novel UV detection devices.

Photochromic materials have great potential applications in many fields due to their reversible color change under light irradiation. Herein, a novel photochromic cotton fabric with high fatigue resistance was creatively fabricated via a facile electrostatic layer-by-layer self-assembly technology of photochromic microcapsules and sodium alginate. Chitosan was used to encapsulate photochromic dyes to form microcapsules to improve fatigue resistance, meanwhile, as the wall material of microcapsules in weak acid environment can provide the positive charge needed for electrostatic layer-by-layer self-assembly process. After the anionic modification of cotton fabric to achieve negative charge, electrostatic layer-by-layer self-assembly was taken place between -NH3+ on the wall material of microcapsules and -COO− in sodium alginate under the condition of pH = 5. For clear characterization of the regular charge changes of fabric surface during the assembly process, the methylene blue (a kind of cationic dye) dyeing of cotton fabrics was carried out, the K/S and Lab value of the dyed fabric showed a regular “odd-even” oscillation. The assembled five-layer microcapsules fabric can change from colorless to purple rapidly within 12 s under UV light, and reversibly return to the original state under the irradiation of green light quickly in 90 s. It can maintain excellent reusability photochromic performance (94.65%) after more than 20 reversible color-changing cycles, implying the good reusability in erasable optical data storage. Furthermore, since the photochromic dyes can absorb UV light, the as-prepared photochromic cotton fabric has excellent UV protection properties.

Tilt sensors have been widely used in many applications, such as instrumentation leveling, oil drilling and structural health monitoring. With the rapid development of the micro-electromechanical system (MEMS) technology, MEMS accelerometer-based high-performance tilt sensors are capable of replacing conventional tilt sensors in most of application fields. High-sensitivity MEMS resonant accelerometers (MRAs) are fully qualified for tilt sensing. However, MRA chips have to be vacuum packaged and require complex circuits; therefore, they are difficult to be miniaturized and commercialized. In this case, this paper introduces a commercial-oriented capacitive MEMS accelerometer for tilt sensing with both high-resolution and compact size. The proposed MEMS sensor utilizes simplified fabrication processes, the area-change-based capacitive displacement transducer and the capacitance-to-voltage conversion application specific integrated circuit (ASIC) for low-cost, high-sensitivity, low power consumption and miniaturization. The developed MEMS sensor has a package dimension of 14 mm × 14 mm × 3.6 mm with a single +5 V power supply and analog voltage output. Several evaluation experiments have been conducted with the results showing that the developed MEMS tilt sensor has a full measurement range of ±180°, a linear measurement range of ±30° with a nonlinearity of ±2.8%, a sensitivity of 33.6 mV/°, a noise floor of 2 × 10−4°/√Hz, a bandwidth of 100 Hz and an angle resolution of 7 × 10−4° with an integral time of 0.5 s. Compared with other commercial MEMS tilt sensors, the proposed sensor has a better resolution, a lower noise floor, a larger bandwidth, a lower power consumption and a smaller package. The simplified fabrication process and high performance suggest the developed MEMS tilt sensor is promising to be competitive in the market.

In this paper, we prepare a novel photochromic hydrophobic cotton fabric with high sensitivity after irradiated by ultraviolet light, excellent fatigue resistance, and good hydrophobic properties. Additionally, it can quickly return to the primary color under conditions of green light, heat or dark, respectively. The target photochromic spiropyrane compound was firstly synthesized and prepared into microcapsules as core and chitosan as shell to improve the fatigue resistance. Polydimethylsiloxane (PDMS) was creatively blended with microcapsules and coated onto the surface of cotton fabric. The presence of PDMS can not only ensure the firmly fixation of microcapsules on the fabric surface, but also endow the fabric with anti-fouling properties due to the hydrophobic effect. The target photochromic compound, photochromic microcapsules and the as-prepared cotton fabrics were confirmed by characterizations. The results indicated that the target photochromic compound was successfully synthesized, and the as-prepared cotton fabric exhibits good hydrophobic properties, long-lasting photochromic properties, including fast color changing properties and outstanding fatigue resistance. Furthermore, the washing fastness of the as-prepared fabrics was also studied, proving their great potential in civilian textiles, especially in outdoor textiles.

Photosensitive polyimide (PSPI) based insulating layer fabrication for microelectromechanical systems (MEMS) application has been systematically investigated in this work. The PSPI was spin coated on a silicon substrate as an insulating layer between two metal lines. In consideration of thermal properties, a low temperature hard bake process was carefully optimized. Finally, the polyimide insulating layer was hardened by exposure to air at 80°C for 120 min + 150°C for 60 min + 180°C for 60 min + 250°C for 60 min + 350°C for 60 min in a dry furnace. Using this optimized hardening process, the outgassing effect in post-fabrication heat treatment can be completely eliminated, which presented an excellent thermal resistance in MEMS fabrications. The reliability test was accomplished through an immersion in organic solvent and acid/base solution in order to verify the corrosion resistance of the PSPI frame for insulating application. The excellent resistance which is on the order of 108 Ω between two metal lines, shows an outstanding insulating property.

A method for removal of passivation polymer residues from deep reactive ion-etching (DRIE) has been systematically investigated in this study. The method combines dry oxygen plasma ashing and conventional photoresist wet stripping. Samples were carefully examined by x-ray photoelectron spectroscopy (XPS), energy-dispersive x-ray spectroscopy (EDX), and study of surface morphology. XPS and EDX analysis showed that the polymer residues consisted mainly of C-O, CF x (x = 1, 2, 3), and C-CF bonds. Optimized oxygen plasma ashing effectively removes most of the fluorocarbon content, except some nano-residues. Subsequent conventional wet stripping in organic solvents could eliminate these stubborn nanoparticles while dissolving the underlying photoresist. Excellent removal is apparent from scanning electron microscopy images. The fluorine content determined by EDX analysis showed that the residues were completely removed. The metal layers, oxide insulator layers, and the polyimide insulators function well after this critical surface treatment. The excellent results show this is an outstanding method for removal of DRIE passivation polymer residues for MEMS fabrication.

A normally-off InAlN/GaN MIS-HEMT with HfZrO 2 gate insulator was realized and investigated. By using N 2 O plasma treatment beneath the gate region, 13 nm InAlN Schottky layer was oxidized to AlON x + 4 nm InAlN Schottky layer. The strong polarization induced carriers in traditional InAlN/GaN 2 DEG quantum well was reduced for enhancement-mode operation. High-k thin film HfZrO 2 was used for gate insulator of E-mode device to further suppress gate leakage current and enhance device gate operation range. The maximum drain current of E-mode InAlN/GaN MIS-HEMT was 498 mA/mm and this value was higher than previous published InAlN/GaN E-mode devices. The measurement results of low-frequency noise also concluded that the low frequency noise is attributed to the mobility fluctuation of the channel and N 2 O plasma treatment did not increase fluctuation center of gate electrode.

In order to meet the requirement of high precision measurement, the resonant frequency of MEMS accelerometer becomes more and more lower. This paper presents a structural design to achieve an extremely low resonant frequency in an MEMS spring mechanism, which is based on nonlinear stiffness beam. The mechanism employs a curved beam to achieve a negative stiffness. By adding this negative stiffness behavior to the positive stiffness of a normal folded beam, a quasi-zero stiffness mechanism can be obtained. Analytic calculation and the finite element analysis (FEA) are used to describe its nonlinear mechanical behavior. The mechanism is fabricated preliminarily and tested to verify a low resonant frequency can be successfully actualized.

Encoder-like micro area-changed capacitive transducers are advantageous in terms of their better linearity and larger dynamic range compared to gap-changed capacitive transducers. Such transducers have been widely applied in rectilinear and rotational position sensors, lab-on-a-chip applications and bio-sensors. However, a complete model accounting for both the parasitic capacitance and fringe effect in area-changed capacitive transducers has not yet been developed. This paper presents a complete model for this type of transducer applied to a high-resolution micro accelerometer that was verified by both simulations and experiments. A novel optimization method involving the insertion of photosensitive polyimide was used to reduce the parasitic capacitance, and the capacitor spacing was decreased to overcome the fringe effect. The sensitivity of the optimized transducer was approximately 46 pF/mm, which was nearly 40 times higher than that of our previous transducer. The displacement detection resolution was measured as 50 pm/√Hz at 0.1 Hz using a precise capacitance detection circuit. Then, the transducer was applied to a sandwich in-plane micro accelerometer, and the measured level of the accelerometer was approximately 30 ng/√Hz at 1Hz. The earthquake that occurred in Taiwan was also detected during a continuous gravity measurement.

Photochromic materials aroused enormous interest due to their potential application for rewritable paper, smart labeling and sensor devices. In this paper, we proposed to dissolve spiropyran (SP, photochromic material) and polyacrylonitrile (PAN, polymer matrix) in dimethyl fumarate (DMF) to prepare photochromic nanofibers by electrospinning. The target SP compounds were featured by FTIR, ultraviolet (UV) and 1HNMR, and the nanofibers were characterized by FTIR, UV-vis spectra, scanning electron microscope (SEM), thermal gravimetric analysis (TGA) and contact angle (CA). The test results demonstrated that photochromic SP was synthesized successfully, and the nanofiber membrane possesses extraordinary color-converting properties including obvious color change from white to purple, reversible fast switching between two colors when exposed to UV light and achieve maximum color change in 1[Formula: see text]min, and switchable hydrophilic and hydrophobic properties as well as excellent photo-fatigue resistance over 20 cycles. In addition, it has good thermal stability allowing it to be used under harsh conditions. In view of the above characteristics, we believe that the as-prepared nanofiber film will be a promising reusable writing substrate.

Fe-based alloy coatings were produced by the plasma transferred arc(PTA) at arc current values of 90A,100A,110A and 120A. Scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and optical microscopy (OM) were used to characterize the microstructure of the coatings. The wear resistances of the coatings were tested by impact and wear experiment. The results show that, the coating and substrate are metallurgy combination, and the coating modified at 110A shows that better wear resistance than others.

This study investigates the characteristics of AlGaN/GaN MIS–HEMTs with HfxZr1−xO2 (x = 0.66, 0.47, and 0.15) high-k films as gate dielectrics. Sputtered HfxZr1−xO2 with a dielectric constant of 20–30 and a bandgap of 5.2–5.71 eV was produced. By increasing the Zr content of HfZrO2, the VTH shifted from −1.8 V to −1.1 V. The highest Hf content at this study reduced the gate leakage by approximately one order of magnitude below that of those Zr-dominated HFETs. The maximum IDS currents were 474 mA/mm, 542 mA/mm, and 330 mA/mm for Hf content of 66%, 47%, 15% at VGS = 3 V, respectively.

Photochromic materials have drawn increasing researchers’ attention due to their excellent reversible discoloration and brilliant physical properties. In this paper, we proposed a novel method of preparing photochromic and thermochromic cotton fabric via thiol-ene click chemistry to establish chemical bonds between spiropyrane derivatives and thiol-modified cotton. The synthesized photochromic materials were characterized by FTIR, 1H NMR and ultraviolet (UV), and the as-prepared fabrics were featured by FTIR and Raman spectra as well as SEM. The results indicated that the photochromic materials have been successfully synthesized and the resultant cotton fabric possesses brilliant and durable photochromic properties, including noticeable and quick color alteration under UV radiation and under heating. Furthermore, the appropriate fatigue resistance and durable washing fastness ensure it a good candidate in the fields of photochromic and thermochromic textile materials.

A novel procedure for the growth of amorphous SiO2 nanowires by a one-step hydrothermal process directly using commercial silicate glass in cheap aqueous ammonium hydroxide without any other catalyst is reported. The effect of concentration of aqueous ammonium hydroxide and reaction time on synthesized product was investigated. It was found that SiO2 nanowires with high aspect ratio can be synthesized using silicate glass at 170 °C in 2.5 mol l−1 aqueous ammonium hydroxide for 7 h. Scanning electron microscopy, high resolution transmission electron microscopy and x-ray diffraction results showed that the products were amorphous SiO2 nanowires with diameters of 20~100 nm and lengths of several tens of micrometers. X-ray photoelectron spectroscopy (XPS) indicated that the SiO2 nanowires retained small amounts of MgO and CaO from the silicate glass. The result of photoluminescence (PL) spectra of the nanowires exhibited a strong, sharp photoluminescence (PL) emission peak, centered at 426 nm. Based on the results, the OH-assisted hydrolysis of the glass has been proposed as the growth mechanism of the SiO2 nanowires.

This paper deals with heat transmission through porous material subjecting to high levels of radiation. In depth absorption of radiant energy would lead to increased in-depth temperature which would cause a thicker pyrolysis zone, that lead to uncontrolled material spallation and failure. Analytical treatments of such problems had been attempted by many researchers [, approaches vary from theoretical principles to engineering correlations, but unfortunately no appropriate temperature and pressure-dependent material properties are available which are needed for their estimations, and extensive experimental measurements would still be required for their evaluations. This paper describes an experimental system developed for direct measurement of radiation transport parameters which is developed with reference to the experimental setups of previous investigators.

Wafer-level hydrophilic silicon direct bonding is demonstrated using ultraviolet ozone (UVO) activation. The activation is performed at room temperature in atmospheric ambient for 3, 6, 9, and 12 min under UVO exposure, respectively. The activation process helps to form a hydrophilic surface (contact angle < 7°) for hydrophilic bonding and to improve the surface roughness to C-V curves of the metal-oxide-semiconductor (MOS) capacitors which are fabricated using UVO clean on the Si surface prove that prolonged exposure to UVO can degrade the bonding quality.

Thermal characteristics of InP-Al2O3/Si bonding for photonic integrated circuits application have been reported in this work. This paper firstly demonstrates low temperature heterogeneous direct bonding assisted by a thin layer of high-κ dielectric material (Al2O3). The InP samples with epitaxial growth layer are bonded to a thin Al2O3 layer coated Si wafer at 250°C under a bonding pressure of 3 MPa for 10 hours in vacuum (∼2.5 × 10−4 mbar) ambient. Focused ion beam (FIB) results show an excellent bonding interface and no voids are observed. Compared with samples using SiO2 as the intermediate layer, the simulation results obtained by COMSOL show an outstanding advantage of thermal dissipation using Al2O3 as the intermediate layer. Thermal characterization is accomplished through a Kelvin structure gold (Au) lines on the Al2O3 and SiO2 layer. Due to the excellent thermal conductivity performance of Al2O3, this high quality heterogeneous direct bonding has potential applications for enhancing the performance of Si photonic integrated devices. ASTAR (Agency for Sci., Tech. and Research, S’pore)

Low-temperature Cu–Cu thermocompression bonding enabled by self-assembled monolayer (SAM) passivation for hermetic sealing application is investigated in this work. Cavities are etched to a volume of 1.4 × 10−3 cm3 in accordance with the MIL-STD-883E standard prescribed for microelectronics packaging. The wafer pairs (nonfunctional cavity wafer and cap wafer) are annealed and bonded at 250°C under a bonding force of 5500 N. The encapsulated cavities undergo helium overpressure in a bombing chamber, and the helium leak rate is detected by a mass spectrometer. The measurement results show that the cavities sealed with Cu–Cu bonding after SAM passivation exhibit excellent hermeticity with a leak rate below 10−9 atm cm3/s, which is an improvement of at least 2× compared with the control sample without SAM passivation.

Hermetic seal and mechanical support of wafer-level Cu-to-Cu thermo-compression bonding with different bonding temperature are analyzed in this work. The investigation consists of two parts: hermetic seal study using helium bomb test and mechanical support study using four-point bending method. The wafer pairs are bonded at 250, 300 and 350 °C, respectively, under a bonding force of 5,500 N for a duration of 1 h in vacuum (~2.5 × 10−4 mbar). The bonding medium consists of Cu (300 nm) bonding layer and Ti (50 nm) barrier layer. Excellent helium leak rate, which is smaller than the reject limit defined by MIL-STD-883E standard (method 1014.10), and outstanding interfacial adhesion energy are detected for all samples. The cavities sealed at 300 °C present an excellent reliability of temperature cycling test up to 500 cycles. Cu-to-Cu thermo-compression bonding at low temperature (≤300 °C) presents an attractive hermetic seal and a robust mechanical support for 3D integration application.

Wafer-on-wafer stacking is demonstrated successfully using bumpless Cu-Cu bonding for the simultaneous formation of electrical connection, mechanical support, and hermetic frame for 3-D IC application. The ohmic behavior of the Cu-Cu bond is verified. A daisy chain of at least 44 000 contacts at a 15-μm pitch is connected successfully and sustains thermal cycling. Postbonding delamination is found to be strongly affected by the wafer curvature and bond strength. The Cu-Cu hermetic seal ring shows a helium leak rate more than ten times lower than the reject limit (5 × 10-8 atm · cm/s based on MIL-STD-883E standard) without underfill. This provides a robust IC-to-IC connection density of 4.4 × 105 cm-2, suitable for future wafer-level 3-D integration.

For the measurement of radiation heat transfer in the low-density nanoporous insulation material at extreme temperature environment, this paper describes in detail on how the experimental optical system is established, and the way and method of measurements are presented .A Silica Aerogel nanoporous insulation plate specimen is experimented and its result is compared with the analytical result, their discrepancies are analyzed. This work is intended to give reference to the development of new types of thermal protection system (TPS) with low density microporous material insulations.