Zahir, Siti Anis Dalila MuhammadOmar, Ahmad FairuzJamlos, Mohd FaizalAzmi, Mohd Azraie Mohd...
15页
查看更多>>摘要：Health monitoring in plants is vital for agricultural sustainability. Currently, the number of techniques able to detect plant stress and disease at an early stage is limited. Prevention of diseases and stress, while the plants are still in an asymptomatic stage could lead to better crop management in agricultural industries. This review focuses on the applications of visible and near-infrared (Vis-NIR) spectroscopy in disease detection and the implications of stress in various species of plants. It is a rapid and non-destructive technique that doesn't require or requires only minimal sample processing before measurements and data analysis. The visible and near-infrared region can detect almost all functional groups and compounds making it a promising tool for data analysis. A brief overview of the methods used and the absorption bands in the Vis-NIR range related to plant disease and stress will be discussed. The comprehensive review of the application of the visible and near-infrared range regions according to different types of disease and stress including the methods used for the data analysis is being addressed.
查看更多>>摘要：We propose and experimentally demonstrate an optical fiber torsion sensor based on symmetrically polished single-multi-single mode (SP-SMS) fiber structure. The polished structure enhances the torsion response effectively, which is fabricated by a high-frequency CO2 laser. Experimental results show that the high sensitivity of the proposed torsion sensor reaches 1.032 nm/(rad m(-1)) in the range from -10.261 rad/m to 10.261 rad/m. Meanwhile, the temperature response of the sensor is also investigated, which is 21 pm/C in the range from 30 ?& nbsp;to 150 ?. Moreover, the structure has the features of low cost, simple fabricating method and small temperature crosstalk.
查看更多>>摘要：The wearable sensors based on image processing possess distinct advantages such as being power-free and without complex wire connections, which are of low cost and easy to manufacture. In this paper, a wearable UV sensor made from photochromic material and PDMS was proposed to be employed in real-time UV monitoring and daily solar protection. The convolutional neural network image processing method was introduced and developed for quantifying UV intensity, and it was shown to decrease the impact of ambient light significantly. The limit of detection of the sensor was about 9 mu W/cm(2) and the recognition rate of the network exceeded 90% under different ambient light conditions. The CNN test was complete within 3 s. Finally, regarding applied scenarios, a UV intensity recognition APP based on a mobile convolutional neural network was designed, which displayed the real-time UV intensity by simple photting.
查看更多>>摘要：Gestures play an important role in human-computer interaction, which provides a natural way for human-machine communication. In this paper, we proposed a new finger motion detection method based on optical fiber Bragg grating (FBG) with polyimide substrate. Several FBGs with polyimide substrate were fixed on the forearm to monitor the deformation around the forearm caused by finger motion. Firstly, the sensors layout was determined according to the distribution of forearm muscles which control finger motions, and the arrangement of FBGs was optimized. Then, through a series of tests, the response characteristics and applicability of the proposed FBG with polyimide substrate were verified. The tests results show that FBG with polyimide substrate has a high sensitivity, good linearity, low hysteresis error and good creep resistance compared with other two substrates. In the experiment of finger motion detection, test data based on six static gestures was adopted to evaluate the availability of the FBGs. The experimental results show that the proposed method can detect six static gestures effectively, and the FBG output signal has good repeatability under the same gesture. This is the first attempt to use FBGs to detect fingers' monitor by monitoring deformations at the forearm, which is a technique with wide application prospects.
查看更多>>摘要：Command shaping is a driving technique for handling the large settling time of the high-Q-MEMS actuators. The strong nonlinearity due to the electrostatic actuation limits the linear operation range in cantilevered or torsional micro-mirrors where command shaping techniques can be applied for positioning. Experimental and simulation results of this research demonstrate the effectiveness of using electrostatic levitation to overcome the actuation nonlinearities and a significant increase in the operation range. The motivation for this research is that applying the nonlinear command shaping causes complexity in command manipulation and requires an accurate knowledge of the nonlinear terms involved in the system model. The large linear operation range generated by the levitating force allows using the practical simple command shaping methods for open-loop control.
查看更多>>摘要：The embedding of electric components into additively manufactured structures offers enormous potential for extending the functionality and applications of parts produced by additive manufacturing (AM). However, the production of electric components embedded with 3D-printed ceramic structures has been a significant challenge due to the complexity of the manufacturing process and the high-temperature post-processing it requires. In the present study, an inductive proximity sensor with a 3D-printed ceramic housing and embedded sensing elements was designed and produced using a hybrid manufacturing process in which the printing process is paused and a sensing element is embedded into the printed structure. Sensing elements materials were carefully selected and intra-sensor structures were developed to ensure that the sensing element would survive in a high-temperature sintering environment. In the developed process, binder-coated zirconia containing 87 wt% was used as feedstock in a piston-based material extrusion process to fabricate the ceramic housing for the sensor, and platinum wire was used in the sensing element. The subsequent debinding and sintering processes achieved a nearly fully dense ceramic housing that protects the sensor in harsh environments. The successfully fabricated sensor was tested by measuring the change of distance between the inductive and metallic target and determining if the changes in distance would alter the inductance of the sensor. Results show that the sensing element maintains functionality throughout each fabrication step, and the fully packaged sensor also demonstrates the ability to work properly at high temperatures (in the range of 200-400 degrees C). At a frequency of 2 MHZ and a voltage of 1 V, the inductive sensor has a measurement range of approximately 7.0 mm. Additive manufacturing of the sensor housing enabled precise control of the geometry, dimensions, and infill density. Because the developed methodology allows for control of the type and structure of the sensing element, it can be used in the manufacture of a wide variety of sensors or smart components.
Hanna, B.Pillai, Lekshmi R.Rajeev, KavyaSurendran, K. P....
9页
查看更多>>摘要：We report the fabrication and characterization of visible-blind UV photodetectors using thin films of polymer/ zinc oxide (ZnO) nanocomposites. Polymer-ZnO nanocomposites based on three polymers, poly(methyl methacrylate)(PMMA), polystyrene(PS) and poly(vinylidene difluoride-trifluoroethylene(P(VDF-TrFE)) were studied. The electrical response of the detectors to 365 nm and 254 nm UV light illumination was probed. P(VDF-TrFE)/ ZnO nanocomposite-based device exhibited the best performance compared to the other devices, possibly due to its ferroelectric property. Further, we prepared P(VDF-TrFE)/ZnO nanocomposite with different wt% of ZnO nanoparticles and characterized them by atomic force microscopy (AFM), X-ray diffraction (XRD), fourier transform- infrared spectroscopy (FTIR), UV-Visible absorption spectroscopy, and Photoluminescence (PL). XRD and FTIR studies confirmed the formation of the beta phase of P(VDF-TrFE) in pristine polymer films and their nanocomposites. The influence of the top electrode material on the photodetector performance of nanocomposites was studied. P(VDF-TrFE)/5 wt% ZnO nanocomposite with Ag top electrode exhibited the best performance with on-off ratio, 1.4 x 10(4); responsivity, 14.43 A/W; linear dynamic range, 83.09 dB and detectivity, 2.27 x 10(13) jones under 365 nm light illumination. The ferroelectric polarization mechanism of P(VDF-TrFE) and the choice of electrode play an important role in the performance of the devices.
查看更多>>摘要：Flexible pressure sensors based on MXene have made significant progress in various fields. However, the development of miniature flexible pressure sensors with high sensitivity and wide sensing range remains a challenge. In this study, a flexible pressure sensor based on MXene and polyvinyl alcohol (PVA) with ultra-high sensitivity, wide sensing range, and miniaturization is fabricated. Owing to the synergistic effect of the surface contact and adjustable conductivity, the developed sensor exhibits an ultra-high sensitivity of 2320.9 kPa(-1), low detection limit of similar to 6 Pa, fast response time of similar to 70 ms, and durability for more than 10,000 cycles. In addition, the MXene/PVA-based sensor has the advantages of simple preparation, low cost, and easy industrialization. Thus, this work paves the way for new applications in flexible electronics, wearable electronic products, and human-computer interactions. This new design strategy provides a solution to solve the urgent demand for flexible pressure sensors with high sensitivity and wide sensing range.
Chew, Bradley S.Fung, Alexander G.McCartney, Mitchell M.Kenyon, Nicholas J....
7页
查看更多>>摘要：Trace chemical detection plays an important role in evaluating environmental hazards as well as benign chemical sources. We have developed a low power dual-polarity ionization-based detector. The detector electronics are operated with a single 9 V battery and provide concentration sensitive voltage outputs. The detection mode can be set manually with the on-board electronics or can be controlled with a microcontroller compatible digital input. The complete assembly and operation of the detector is detailed. The features of the detector make it suitable to be operated as a standalone system or to be integrated as a sub-system into a field-portable analytical platform. The detector can achieve a system step response of ~1.6 s. We performed laboratory measurements with several ionized chemicals using both positive and negative mode. The results showed highly linear responses at trace concentrations as low as 100 ppb.
de Bem, Nata F. S.Ruppert, Michael G.Fleming, Andrew J.Yong, Yuen K....
14页
查看更多>>摘要：The use of integrated on-chip actuation simplifies the identification of a cantilever resonance, can improve imaging speed, and enables the use of smaller cantilevers, which is required for low-force imaging at high speed. This article describes a cantilever with on-chip actuation and novel dual-sensing capabilities for AFM. The dualsensing configuration allows for tip displacement and tip force to be measured simultaneously. A mathematical model is developed and validated with finite element analysis. A physical prototype is presented, and its calibration and validation are presented. The cantilever is optimized for use in off-resonance tapping modes. Experimental results demonstrate an agreement between the on-chip sensors and external force and displacement measurements.
NSTL
Elsevier