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This study reports an insightful portable vector network analyser (VNA)‐based measurement technique for quick and selective detection of Hg2+ ions in nanomolar (nM) range using homocysteine (HCys)‐functionalised quartz‐crystal‐microbalance (QCM) with cross‐linked‐pyridinedicarboxylic acid (PDCA). The excessive exposure to mercury can cause damage to many human organs, such as the brain, lungs, stomach, and kidneys, etc. Hence, the authors have proposed a portable experimental platform capable of achieving the detection in 20–30 min with a limit of detection (LOD) 0.1 ppb (0.498 nM) and a better dynamic range (0.498 nM–6.74 mM), which perfectly describes its excellent performance over other reported techniques. The detection time for various laboratory‐based techniques is generally 12–24 h. The proposed method used the benefits of thin‐film, nanoparticles (NPs), and QCM‐based technology to overcome the limitation of NPs‐based technique and have LOD of 0.1 ppb (0.1 μg/l) for selective Hg2+ ions detection which is many times less than the World Health Organization limit of 6 μg/l. The main advantage of the proposed QCM‐based platform is its portability, excellent repeatability, millilitre sample volume requirement, and easy process flow, which makes it suitable as an early warning system for selective detection of mercury ions without any costly measuring instruments. [ABSTRACT FROM AUTHOR]

In this study, the authors demonstrate the fabrication, calibration, and testing of a piezoresistive microcantilever‐based sensor for biomedical microelectromechanical system (BioMEMS) application. To use any sensor in BioMEMS application requires surface modification to capture the targeted biomolecules. The surface alteration comprises self‐assembled monolayer (SAM) formation on gold (Au)/chromium (Cr) thin films. So, the Au/Cr coating is essential for most of the BioMEMS applications. The fabricated sensor uses the piezoresistive technique to capture the targeted biomolecules with the SAM/Au/Cr layer on top of the silicon dioxide layer. The stiffness (k) of the cantilever‐based biosensor is a crucial design parameter for the low‐pressure range and also influence the sensitivity of the microelectromechanical system‐based sensor. Based on the calibration data, the average stiffness of the fabricated microcantilever with and without Au/Cr thin film is 141.39 and 70.53 mN/m, respectively, which is well below the maximum preferred range of stiffness for BioMEMS applications. The fabricated sensor is ultra‐sensitive and selective towards Hg2+ ions in the presence of other heavy metal ions (HMIs) and good enough to achieve a lower limit of detection 0.75 ng/ml (3.73 pM/ml). [ABSTRACT FROM AUTHOR]

This study describes a low‐cost sensor‐based scheme for online moisture measurement in transformer oil. Considering a harsh environment, moisture measurement of oil at ppm level is challenging, so the sensor should be highly sensitive and thermally and chemically stable. The conventional methods are mostly offline, have long test times and are costly. A thin‐film parallel plate capacitive moisture sensor has been fabricated using inexpensive materials to measure the moisture of fresh, aged and 0.5% water content oil samples. The moisture sensing film is highly hydrophilic and is made of alumina oxide, a very stable material. Experiments were conducted to determine the response parameters of the sensor in the presence of moist nitrogen gas, the concentration of which was measured by a commercial SHAW dew point meter. Experiments were also performed to measure the moisture of different oil samples in the laboratory. Results show that the output of the sensor is sensitive (6 pF/ppm moisture), has negligible hysteresis (∼1% at 1 kHz) and has fast response and recovery times (Tres = 70 s, Trec = 170 s). [ABSTRACT FROM AUTHOR]

To diagnose the running state of bushing and avoid serious power grid accidents, online multi‐parameter monitoring equipment for dissolved hydrogen, oil pressure and temperature in bushing oil was developed. The equipment includes three units: signal acquisition, control cabinet and data analysis. A new hydrogen sensor without oil–gas separation membrane and based on palladium alloy film technology was developed. A three‐in‐one sensor for hydrogen, oil temperature and pressure monitoring has been developed, which has the advantages of miniaturisation, lightweight and easy installation. Test results show the hydrogen measurement range of the sensor is 0–5000 ppm, and the accuracy can reach 10% or 15 ppm (with larger values). The pressure measurement range is 0–1.0 MPa, the resolution is 0.1 kPa, and the accuracy can reach 0.25 grade. The temperature measurement range is −40 to 105°C, and the accuracy is ±1°C. The measurement performance of the device fully meets the requirement of online monitoring of transformer bushing. The equipment has been put into operation in a 330 kV substation, which can monitor the bushing status online and help eliminate the early latent fault of bushing in the weak budding state. [ABSTRACT FROM AUTHOR]

The authors report quartz crystal microbalance (QCM) integrated with hexagonal boron nitride–graphene (hg) monolayer heterostructure as a sensor to detect mass flow of sulphur hexafluoride (SF6), an important electrical insulating gas, under humid conditions. Their recent work demonstrated an enhancement in QCM sensing characteristics upon attaching monolayer 2D materials onto the QCM electrode surface and its application for improved relative humidity measurement. Here, they extend this approach to detect flow of SF6 gas causing variation in relative humidity. They fabricated a hg-QCM sensor by transferring the heterostructure thin film onto the QCM electrode surface using a standard wet transfer technique and measured return loss of the QCM under SF6 gas flow at a selected RH condition. The mass flow of the humid SF6 gas effects perturbation in damping at the QCM surface as indicated by changes in the motional resistance of the QCM. The motional resistance changes introduced significant variation in loaded Q-factor, the magnitude of which was gas species-dependent, thus allowing to distinguish SF6 from other common electronics gases. [ABSTRACT FROM AUTHOR]

This paper presents the effect of thermal annealing on β-Ga2O3 thin film solar-blind (SB) photodetector (PD) synthesized on c-plane sapphire substrates by a low pressure chemical vapor deposition (LPCVD). The thin films were synthesized using high purity gallium (Ga) and oxygen (O2) as source precursors. The annealing was performed ex situ the under the oxygen atmosphere, which helped to reduce oxygen or oxygen-related vacancies in the thin film. Metal/semiconductor/metal (MSM) type photodetectors were fabricated using both the as-grown and annealed films. The PDs fabricated on the annealed films had lower dark current, higher photoresponse and improved rejection ratio ( R250/ R370 and R250/ R405) compared to the ones fabricated on the as-grown films. These improved PD performances are due to the significant reduction of the photo-generated carriers trapped by oxygen or oxygen-related vacancies. [ABSTRACT FROM AUTHOR]

The design and fabrication of various types of flexible, portable, and foldable devices have received immense interest owing to the remarkable potential in impacting peoples' lives including real‐time health monitoring, point‐of‐care diagnosis, and athletic training. In this work, the authors present 3D graphite as the key sensing element of polymer composite strain sensors that offers ultrahigh sensitivity and durability in the detection of fine motions. The graphite–polymer sensors in this work provide high bending sensitivities that are reproducible within 3% signal shift after 11 000 bending cycles and exhibit gauge factors of 100 and 52 at tensile strains of 80% and 100%, respectively. The sensing mechanism is modeled, and correlated with experimental studies. The high strain sensitivity compared to graphene based devices is analyzed and understood with respect to levels of defect in materials. Such graphite–polymer sensors are able to detect fine features of human pulses, respiration rates, and throat vibration in real time and are also applied in the detection of posture correctness of musical instrument learners for the first time. [ABSTRACT FROM AUTHOR]

Capacitive fringing field sensors have been used in some non‐contact detections. A lateral displacement measurement method based on fringing field capacitors is investigated by simulations and experiments in this study. For the conventional interdigitated structure, the periodic electric field distribution is obtained because of those alternate electrodes, which produces periodic capacitances along with the target displacement. However, it is inconvenient to construct measurement systems due to the non‐linear capacitance output. A dentate structure is proposed to improve the output characteristics of displacement measurement. The periodic uniform electric field is achieved by the dentate electrodes, which brings the linear capacitance variation in every period. Indium–tin oxide film was employed to fabricate a prototype, and the experiment results indicate that the dentate structure can be used in the lateral displacement measurement for its linear output characteristics. [ABSTRACT FROM AUTHOR]

SUMMARY Cr-N thin films, which have a gauge factor of about 16 and a temperature coefficient of resistivity close to zero, are a promising new next-generation strain gauge material. In this paper, the fabrication and characterization of a single-module system of the load vector sensor using the Cr-N strain-sensitive thin films, which can be applied to sole sensors, are reported. [ABSTRACT FROM AUTHOR]

A new humidity sensor based on graphene oxide quantum dots (GOQDs)/polyelectrolyte [polymer (diallylimethyammonium chloride) (PDDA)] composite sensing films was proposed. A few layers of GOQDs anchor on PDDA were prepared on the substrate via covalent bonds. A 0D scale, hydrophilicity, and super‐permeation of GOQDs endow the sensor an ultrafast response with about 32 ms response time and 48 ms recovery time. Meanwhile, the response was hardly affected due to covalent anchor of the composite film even after the sensor was soaked in water for several times. [ABSTRACT FROM AUTHOR]

The development of carbon nanotube (CNT)‐based sensors remains an active area of research. Towards this end, a new method for manipulating CNTs, assembling CNT networks and fabricating CNT‐based nanosensors was demonstrated in this study. CNTs were collected and concentrated by optically‐induced dielectrophoresis (ODEP) forces and aligned between a pair of electrodes. This assembly was then used directly as a temperature sensor and a hot‐film anemometer, which detects changes in windspeed. By offering efficient CNT collection and ready‐to‐use sensor fabrication, this ODEP‐based approach presents a promising method for the development of CNT‐based sensing applications and massively parallel assembly of CNT‐lines. The developed CNT‐based nanosensors may be used to measure the temperature and the flow velocity of bio‐samples in the near future. [ABSTRACT FROM AUTHOR]

How the application of commercial (thin film) flat panel display technology, used in the production of flexible displays and flexible digital X‐ray detectors, can also be applied to reduce the manufacturing cost of wearable biomedical devices, as well as potentially improve their diagnostic functionality, is explored. As a technology platform to evaluate the presented new concept, a prototype photoplethysmograph biosensor using a flexible organic light‐emitting diode display and pin photodiode (thin film) sensor technology for optical heart rate monitoring is developed. [ABSTRACT FROM AUTHOR]

A thin film of silica aerogel has been spin coated on silicon wafers to investigate its super thermal insulating capability. The temperature of the thin film heaters fabricated on the aerogel coated wafer is measured at different applied powers. Simulations are performed to compare the aerogel coated wafers with the micromachined wafers. Both experimental and simulation results show better heat insulation for aerogel coated wafers as compared with simulated micromachined wafers. The measurement and simulation results of aerogel coated wafers are in good agreement. The aerogel film can replace the air cavity created by conventional micromachining of wafers to save power and chip area in metal oxide gas sensor arrays. [ABSTRACT FROM AUTHOR]

A surface plasmon resonance (SPR) sensor based on exposed‐core microstructured optical fibres (EC‐MOFs) is presented and numerically characterised. The exposed section (analyte channel) of the EC‐MOF is coated with a SPR supporting thin film of gold. The asymmetrically coated fibre can support two separate resonance peaks, with orthogonal polarisations (x‐ and y‐polarised peaks). Although the sensitivity of both the polarised peaks is very similar, the narrower linewidth of the y‐polarised peak provides a much enhanced signal‐to‐noise ratio. The SPR sensing performance for a large refractive index (RI) range from 1.33 to 1.42 is evaluated. The sensor has higher sensitivity for detecting the high analyte RI. The feasibility of using EC‐MOFs to develop a fast‐response, real‐time and distributed SPR sensor is determined. [ABSTRACT FROM AUTHOR]

A multi‐stage thin film transistor (TFT)‐based active pixel sensor (APS), capable of successfully detecting small impulses of charge resulting from incident alpha particle strikes, is presented. Detection of alpha particles is important in the field of neutron detection, where fully integrated thin‐film‐based detectors are an attractive alternative to conventional 3He‐based proportional counters owing to their low‐cost and large‐area scaling capability, combined with the use of readily available materials. A typical TFT process, however, produces only N‐type devices with low electron mobilities – making high‐gain CMOS amplifier designs unfeasible. The disadvantages of using a TFT‐only APS design are mitigated by cascading multiple low‐gain TFT amplifiers, which results in a higher overall pixel gain – subsequently allowing for the successful detection and readout of alpha particle strikes. Presented is a new APS fabricated in an indium gallium zinc oxide TFT process is presented, and successful initial alpha response measurements are reported. [ABSTRACT FROM AUTHOR]

A new method to analyse the contact resistance of a carbon nanotubes (CNTs) humidity sensor is proposed. By analysing the Cole‐Cole plots of the sensor impedance, which was tested by an electrochemical workstation in different RH environments, the contact resistance could be achieved. According to this novel analytical method and the experimental data, the contact resistance of the sensor was about 5 Ω, which was much smaller than the resistance of the sensing film. [ABSTRACT FROM AUTHOR]