Sensors and Actuators A-physical最新文献

Environmental monitoring for detection of harmful pollutants is a challenge in today’s world. Development of wearable sensors with cost-effectiveness and practicality, while using accessible electronic components can be a solution to this challenge. In the present work ultraviolet light emitting diodes (UV-LEDs) and a Light Dependent Resistor (LDR) pair with carefully designed programmable circuitry is used to detect Nitrogen Dioxide (NO₂) in the environment. The sensor is battery operated and rechargeable, making it convenient and eco-friendly. The sensor developed is miniaturized and wearable in nature for the detection of analyte gas in the environment. The sensor is stable and inexpensive as compared to the existing NO₂ sensors available, which are electro-chemical, or oxide based. The sensor system is sensitive and selective to its exposure to NO₂ gas and has no interference with typical environmental attributes such as humidity and temperature, which is a common challenge in gas detection technologies. The principle of gas detection is absorption based, light falling on the detector absorbed by the test gas present in the environment, thus changing the detector resistance. Absorption-based gas detection is indigenously simple but highly effective technique. This method not only ensures good sensitivity but enhances the selectivity of the electro-optical sensor towards the test gas preventing false triggering in the presence of other interfering gases.

In this paper, we proposed the first wireless multiparameter monitoring method for cryogenic environments (−196 ℃). Present-day cryogenic industries implement a large array of wired sensors to monitor key parameters in fabrication processes. The wirings for a large sensor array greatly complicate the monitoring system. We presented the first wireless multiparameter monitoring method for cryogenic environments by making two efforts. First, a novel wireless passive vibration and pressure sensor is developed. We transfer vibrations and pressures to a relative displacement between a magnet and a tunnel magnetoresistor (TMR). This affects the magnetic field at the TMR and changes the TMR’s resistance. By integrating the TMR on a backscattering antenna, the antenna’s wireless return loss is modulated by both vibrations and pressures. We proposed a decoupling method for simultaneously monitoring vibration and pressure by a single sensor. Second, we demonstrated and evaluated the first wireless multiparameter cryogenic monitoring system. A wireless passive temperature sensor is developed by integrating a resistance temperature detector (RTD) on a backscattering antenna. The developed vibration and pressure sensor and temperature sensor are tuned to separate frequency bands, embedded in cryogenic environments, and calibrated in situ. Vibrations, pressures, and temperatures in cryogenic environments are synchronously obtained by our wireless cryogenic monitoring system, with an accuracy of 80∼90 %. This research provides a wireless option in large-scale automated cryogenic monitoring, thus it is desirable in implementing the Internet of Things in cryogenic industries.

In this study, the steady-state creep deformation properties of 5 μm-thick single crystal silicon (Si) films at elevated temperatures were investigated using punch creep-forming tests for the design of three-dimensional (3-D) microstructured MEMS. The relationship between the creep strain rate and stress of the Si films with {100}, {110}, and {111} planes at temperatures of 1223–1323 K was derived using finite element analysis following punch creep-forming tests, and a power-law creep constitutive equation for Si films was determined. The steady-state creep properties of the Si film samples varied clearly with crystallographic orientations. Among the three crystallographic orientations, the creep strain rate of the micron-thick Si films was the fastest for the {011} plane, followed by the {111} and {001} planes, in the applied stress range of 110 MPa to 220 MPa. This is consistent with the increasing order of magnitude of the thermal activation energy. The crystallographic orientation dependence of the steady-state creep properties of Si films is discussed based on the mobility of dislocation gliding per unit lattice and scanning electron microscope observations. The sample-size dependence of the creep strain rate of Si with the {001} plane was clearly observed between the micron- and millimeter-thick samples, which was attributed to the difference in the frequency factor of the power-law creep. However, the thermal-activation energy remained constant. This study successfully revealed the steady-state creep properties of Si films and provided useful engineering data for the design of 3-D Si-MEMS fabrication by the plastic processing of Si films.

Electromagnetic acoustic transducer (EMAT) is widely applied for non-contacting ultrasonic testing of metallic structures. In this paper, an enhanced flexible EMAT is proposed and optimized to improve ultrasonic energy conversion efficiency by adopting an array magnetic core to a racetrack coil-type flexible electromagnetic magnet in replacement of the conventional bias permanent magnet. Numerical simulations and experimental investigations conducted with prototype transducers of the enhanced flexible EMAT show that the bias magnetic field and the energy conversion efficiency of the new EMAT can be significantly enhanced due to the application of the magnetic core array. Thanks to the advantage of flexible magnet structure, it is proved that the proposed new EMAT has good performance to detect surface cracks in curved metallic structural components.

Although the correlation between a glucose concentration and its permittivity is somewhat weak to be measured, the glucose concentration is a strong function of the dispersion. In terahertz or microwave frequencies, dispersion can be observed or measured along the interface between an object under test and a metamaterial or surface plasmonic surface, which is basically a metal structure characterized by periodically arrayed holes, grooves, or metal grating. In this work, we have focused on the method for improving the accuracy of a glucose measurement by proposing a new triple-band microwave sensor design and by measuring the resonant frequency shift associated with a glucose concentration at three frequencies simultaneously. A new triple-band glucose sensor of dimension (30 mm x 10 mm) was designed with the main sensing region as compact as 14 mm with two conducting microstrip lines on both ends of the sensor. The sensor design has been realized on a thin flexible substrate of 0.15 mm thickness. The proposed sensor has been designed to measure glucose concentration through the measurement of a resonant frequency shift at 650 MHz, 4.45 GHz, and 10.35 GHz. Overall, the glucose concentration has been found to be correlated positively and linearly with the resonant frequency shift at these frequencies.

In the field of beam pointing and optoelectronic imaging, there is a growing demand for control mechanisms that offer large stroke, and high bandwidth. These are precisely the characteristics of hybrid reluctance actuator, which therefore is increasingly being used in XY stage to replace piezo-actuator and voice coil motor. This study presents a hollow XY stage utilizing hybrid resistance actuators, aiming to adapt to optical applications with inherent nonlinearity and biaxial coupling, which are further modeled and compensated to mitigate their impacts. Firstly, the basic composition and working principle of the hollow XY stage are described, and the impact of its nonlinearity and biaxial coupling characteristics is elucidated. Secondly, the sources of nonlinearity and biaxial coupling are analyzed, and an analytical model of hybrid reluctance actuators is established. The magnetic leakage coefficient of the model is determined, and the accuracy of the model is verified by Finite Element Method (FEM) and experiment, demonstrating consistency with the analytical model's results. Furthermore, based on the nonlinear and biaxial coupling model, a compensator based on feedback linearization method is established, and verified through experiment. The results show that this method has a significant suppression effect on nonlinear and biaxial coupling, and the tracking error and cross-talk is obviously reduced, which proves the effectiveness of this compensation method.

This paper focuses on accurate and precise orientation estimation with consumer-grade MEMS-IMUs for ‘slow’ orientation change and ‘short’-time applications. A simulation platform is developed to predict a suitable algorithm for a MEMS-IMU of known noise specifications, improving similar works. Experimentally measured noise characteristics of two commercial grade IMUs (MPU9250 and BNO055) are used in the simulation platform to generate simulated data and evaluate some popular orientation estimation algorithms along with two new Kalman filter-based algorithms. Real experiments are conducted with the same IMUs using an electromagnetic tracker as reference sensor. The output orientation results for two new improved algorithms are compared with other algorithms in simulations and real experiments. We show that the choice of the ‘best’ algorithm varies with the noise characteristics of individual sensors within the sensor module. The two new best-performing algorithms tested achieve<1˚ RMS angle error for the two low-cost consumer-grade IMUs.

This study explores the improved ultraviolet (UV) photodetection performance of ZnO nanorods (ZnO NRs) decorated with BaTiO₃ nanoparticles (BT NPs) synthesized using a novel vapor-thermal method (VTM) leading to the formation of a heterojunction upon UV activation that enhances charge separation and reduces charge carrier’s recombination. Initially, ZnO NRs were prepared via a hydrothermal method followed by decoration with BT NPs using the innovative VTM process. To elucidate the morphology and composition of the BT-decorated ZnO NRs, a comprehensive characterization was performed using various techniques, including field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XRD). Photoluminescence (PL) and diffuse reflectance spectroscopy (DRS) are employed to study electronic band structure of the BT decorated and undecorated samples. The BT nanoparticle-decorated ZnO NRs exhibited a higher photodetection performance compared to bare ZnO NRs under 365 nm UV light illumination. This improvement is manifested by a lower dark current, a faster rise time (from 2 s to 0.75 s), a shorter decay time (from 46 s to 0.96 s), and higher sensitivity (from 57 to 135). These findings demonstrate the promising potential of the BT nanoparticle-decorated ZnO NRs for application in high-performance UV photodetectors.

With the emergence of new sensing technologies, there is upcoming demand of high performance, small size and power efficient electronic sensors. Next-generation electronic sensor technology will be more advanced, miniaturized and power efficient. There are variety of sensing and transduction technologies label as piezoresistive, piezoelectric, capacitive, thermoelectric, magnetic and acoustic wave-based principles. Each technology has associated merits and drawbacks. Bulk acoustic wave (BAW) resonator-based sensor show the benchmarking performance which is not possible by any other competing sensing technology. It is perceived that BAW resonator-based sensor provide high sensitivity and selectivity. Therefore, there is huge demand of high frequency operating bulk acoustic wave resonators based electronic sensors. High frequency device operation is limited by many factors such as piezoelectric material layer quality, acoustic wave losses, film thickness and device area became very small in the sub-6 GHz regime. Electronic sensors are ubiquitous and seems to be an economy engine and largest growing segment in the electronic devices and sensor segment. Here, we review, the state-of-the-art development and recent breakthroughs in bulk acoustic wave resonators highlighting the major ongoing research. The review describes various piezo-electric materials property and various bulk acoustic wave resonators in detail. Some promising applications capitalizing the sensing techniques along with the characteristics and performance of bulk acoustic wave devices are also explained in the context of recent development. The prime objective of this review is to provide an up-to-date scientific framework related to this niche emerging research area. The survey reveals the potential of bulk acoustic wave resonators for different sensing applications while several critical challenges have to be still overcome. Finally, insights are represented and future perspectives of bulk acoustic wave resonators along with their structures are discussed.

This paper designs and fabricates a MEMS deformable mirror with 61 electrodes driven by piezoelectric thin films (PZT) to achieve high voltage. This approach effectively corrects wavefront aberrations. Initially, the structural design and MEMS process scheme for the proposed deformable mirror are determined. Numerical simulations of electrode effects are conducted, and the working voltage and motion performance of the reflective mirror are tested using a digital interferometer. Experimental measurements of the surface deformation displacement of deformable mirrors with different electrodes are performed. A comparison of the simulation and experimental results indicates small coupling effects among the designed deformable mirror electrodes. The applied voltage and displacement response exhibit good linearity. Finally, based on the Zernike matrix model, the mirror surface shape is controlled, and Zernike polynomials of orders 2–4 are fitted. The results demonstrate that the deformable mirror has a high correction efficiency for low-order aberrations. Therefore, the proposed MEMS deformable mirror based on PZT piezoelectric thin films exhibits excellent motion and optical correction capabilities.