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Narrow Absorption in ITO-Free Perovskite Solar Cells for Sensing Applications Analyzed through Electromagnetic Simulation
摘要： This work reports on a computational analysis of how a modi?ed perovskite cell can work as a refractometric sensor by generating surface plasmon resonances at its front surface. Metal-dielectric interfaces are necessary to excite plasmonic resonances. However, if the transparent conductor (ITO) is replaced by a uniform metal layer, the optical absorption at the active layer decreases signi?cantly. This absorption enhances again when the front metallic surface is nanostructured, adding a periodic extruded array of high aspect-ratio dielectric pyramids. This relief excites surface plasmon resonances through a grating coupling mechanism with the metal surface. Our design allows a selective absorption in the active layer of the cell with a spectral response narrower than 1 nm. The photo-current generated by the cells becomes the signal of the sensor. The device employs an opto-electronic interrogation method, instead of the well-known spectral acquisition scheme. The sensitivity and ?gure of merit (FOM) parameters applicable to refractometric sensors were adapted to this new situation. The design has been customized to sense variations in the index of refraction of air between 1.0 and 1.1. The FOM reaches a maximum value of 1005 RIU?1, which is competitive when considering some other advantages, as the easiness of the acquisition signal procedure and the total cost of the sensing system. All the geometrical and material parameters included in our design were selected considering the applicable fabrication constrains.
关键词： optical sensor,surface plasmon resonance,opto-electronic interrogation,perovskite ITO free
更新于2025-09-12 10:27:22
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Development of Graphene Quantum Dots-Based Optical Sensor for Toxic Metal Ion Detection
摘要： About 71% of the Earth’s surface is covered with water. Human beings, animals, and plants need water in order to survive. Therefore, it is one of the most important substances that exist on Earth. However, most of the water resources nowadays are insu?ciently clean, since they are contaminated with toxic metal ions due to the improper disposal of pollutants into water through industrial and agricultural activities. These toxic metal ions need to be detected as fast as possible so that the situation will not become more critical and cause more harm in the future. Since then, numerous sensing methods have been proposed, including chemical and optical sensors that aim to detect these toxic metal ions. All of the researchers compete with each other to build sensors with the lowest limit of detection and high sensitivity and selectivity. Graphene quantum dots (GQDs) have emerged as a highly potential sensing material to incorporate with the developed sensors due to the advantages of GQDs. Several recent studies showed that GQDs, functionalized GQDs, and their composites were able to enhance the optical detection of metal ions. The aim of this paper is to review the existing, latest, and updated studies on optical sensing applications of GQDs-based materials toward toxic metal ions and future developments of an excellent GQDs-based SPR sensor as an alternative toxic metal ion sensor.
关键词： metal ion,graphene quantum dots,surface plasmon resonance,optical sensor
更新于2025-09-11 14:15:04
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[IEEE 2019 IEEE International Instrumentation and Measurement Technology Conference (I2MTC) - Auckland, New Zealand (2019.5.20-2019.5.23)] 2019 IEEE International Instrumentation and Measurement Technology Conference (I2MTC) - A Deformation Sensor based upon Light Attenuation in a Silicone Waveguide: Construction and Characterisation
摘要： The measurement of the displacement of soft robotic devices and configurations of actuators is essential for the implementation of force and position control. Conventional deformation sensors, such as capacitive and resistive, are unable to achieve the large extensions required to accurately measure these configurations. Recent advances in flexible optical deformation sensors over the last four years have provided sensor technologies that can measure the large extensions that are experienced in soft actuators. However, the majority of existing optical sensors suffer from performance issues relating to unknown losses in optical power and the lack of immunity to external light sources. To address these issues, a simple optical sensor, constructed using a silicone elastomer, has been tested. By measuring the ratio of two wavelengths of light with different attenuation coefficients, the effects of wavelength dependent optical losses and external light interference can be addressed. A clear silicone sensor was characterised using a RGB LED over 500 extension cycles up to 100 % extension, giving a repeatable output and low and linear hysteresis over all 500 cycles. The effect of different optical dyes was investigated, showing that different dyes can controllably attenuate specific wavelengths and thus affect the sensitivity of the measurements. This investigation demonstrates that a ratioed wavelength flexible optical deformation sensor is capable of repeatable measuring large deformations, suitable for use in a range of applications.
关键词： Deformation,Optical,Sensor,Transducer,Strain,Silicone,Robotic,Elastomer
更新于2025-09-11 14:15:04
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Solvothermal assisted phosphate functionalized graphitic carbon nitride quantum dots for optical sensing of Fe ions and its thermodynamic aspects
摘要： A facile method has been proposed for the determination of Ferrous (Fe(II)) and Ferric (Fe(III)) ions using phosphate functionalized graphitic carbon nitride quantum dots (Ph-g-CNQDs) in an aqueous medium. The easy solvothermal procedure using oleic acid as the solvent yielded the Ph-g-CNQDs in less than 30 min. The communication among the Fe(II) and Fe(III) with Ph-g-CNQDs caused quenching of the blue Ph-g-CNQDs fluorescence signals. The Ph-g-CNQDs have been successfully characterized using X-ray diffractometry (XRD), X-ray Photoelectron spectroscopy (XPS), Transmission electron microscopy (TEM), Fourier Transform Infrared (FT-IR) spectroscopy, UV–vis absorption and photoluminescence spectrophotometry. The temperature dependent behavior of the Ph-g-CNQDs was also observed and various thermodynamic parameters have also been evaluated. The Ph-g-CNQDs displayed an excellent quantum yield of 60.54% using quinine sulfate as the standard reference. The developed method has been applied to water samples collected from different sources and good recoveries were observed which entitles this method as apt for real time monitoring.
关键词： Fe(III),Quantum yield,Optical sensor,Photoluminescence,Fe(II),Phosphate functionalized g-CNQDs
更新于2025-09-11 14:15:04
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3D Reconstruction of Slug Flow in Mini-Channels with a Simple and Low-Cost Optical Sensor
摘要： The present work provides a new approach for 3D image reconstruction of gas-liquid two-phase flow (GLF) in mini-channels based on a new optical sensor. The sensor consists of a vertical and a horizontal photodiode array. Firstly, with the optical signals obtained by the vertical array, a measurement model developed by Support Vector Regression (SVR) was used to determine the cross-sectional information. The determined information was further used to reconstruct cross-sectional 2D images. Then, the gas velocity was calculated according to the signals obtained by the horizontal array, and the spatial interval of the 2D images was determined. Finally, 3D images were reconstructed by piling up the 2D images. In this work, the cross-sectional gas-liquid interface was considered as circular, and high-speed visualization was utilized to provide the reference values. The image deformation caused by channel wall was also considered. Experiments of slug flow in a channel with an inner diameter of 4.0 mm were carried out. The results verify the feasibility of the proposed 3D reconstruction method. The proposed method has the advantages of simple construct, low cost, and easily multipliable. The reconstructed 3D images can provide detailed and undistorted information of flow structure, which could further improve the measurement accuracy of other important parameters of gas-liquid two-phase flow, such as void fraction, pressure drop, and flow pattern.
关键词： Support Vector Machine,3D image reconstruction,gas-liquid two-phase flow,mini-channels,optical sensor,slug flow
更新于2025-09-11 14:15:04
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A metamaterial/liquid-core waveguide microfluidic optical sensor
摘要： This paper introduces the design of a novel micro?uidic refractometric optical sensor. The sensor is able to detect a liquid analyte by converting the change in the refractive index (RI) of the analyte to a shift of resonance peak in the output spectrum. A liquid-core waveguide and gold/dielectric metamaterial are integrated in the sensor design, producing resonance in the waveguide when the light interacts with the metamaterial structure in the core. Finite element analysis is used to simulate the properties of the sensor to optimize the design. Sample sensors are fabricated and tested with liquid analytes which have known refractive indices. Experimental results are well matched to the simulation proving high sensitivity and good repeatability of the sensors. A sensitivity greater than 1280 nm/RIU is achieved by this novel sensor.
关键词： Optical Sensor,Metamaterial,Liquid Core Waveguide
更新于2025-09-11 14:15:04
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Long-Term Behavior of Hydrogenated Amorphous Silicon Thin-Film Transistors Covered With Color Filters for Use in Optical Sensors
摘要： This work investigates the long-term behavior of photo thin-film transistors (TFTs) that are covered with color filters and based on hydrogenated amorphous silicon (a-Si:H) technology. Based on the electrical characteristics and the optical responses of these TFTs as measured under different stress conditions, a new method for driving a photo TFT with a negative gate-source voltage is proposed to suppress the degradation of the photocurrent. The effectiveness of the newly proposed method is verified using our previously developed white-light photocurrent gating (WPCG) structure, the measurement of photocurrents, and the established models of red, green, and blue photo TFTs. An accelerated lifetime test of the fabricated circuit was carried out at 70 ?C and under the illumination of ambient light for 504 hours, demonstrating that the proposed method improves the long-term reliability of optical sensors.
关键词： optical sensor,Hydrogenated amorphous silicon thin-film transistor,long-term reliability
更新于2025-09-11 14:15:04
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Development of a Cost-Effective Optical Sensor for Continuous Monitoring of Turbidity and Suspended Particulate Matter in Marine Environment
摘要： A cost-effective optical sensor for continuous in-situ monitoring of turbidity and suspended particulate matter concentration (SPM), with a production cost in raw materials less than 20 €, is presented for marine or fluvial applications. The sensor uses an infrared LED and three photodetectors with three different positions related to the light source—135o, 90o and 0o—resulting in three different types of light detection: backscattering, nephelometry and transmitted light, respectively. This design allows monitoring in any type of environment, offering a wide dynamic range and accuracy for low and high turbidity or SPM values. An ultraviolet emitter–receiver pair is also used to differentiate organic and inorganic matter through the differences in absorption at different wavelengths. The optical transducers are built in a watertight structure with a radial configuration where a printed circuit board with the electronic signal coupling is assembled. An in-lab calibration of the sensor was made to establish a relation between suspended particulate matter (SPM) or the turbidity (NTU) to the photodetectors’ electrical output value in Volts. Two different sizes of seashore sand were used (180 μm and 350 μm) to evaluate the particle size susceptibility. The sensor was tested in a fluvial environment to evaluate SPM change during sediment transport caused by rain, and a real test of 22 days continuous in-situ monitoring was realized to evaluate its performance in a tidal area. The monitoring results were analysed, showing the SPM change during tidal cycles as well as the influence of the external light and biofouling problems.
关键词： in-situ measurement,turbidity optical sensor,oceanography,suspended particulate matter
更新于2025-09-11 14:15:04
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A PWM based readout circuit for optical sensors with adaptive frequency control
摘要： This paper proposes a pulse-width modulation-based readout circuit for optical sensors which adopts adaptive frequency control technique to enhance input dynamic range of current sensing systems. The proposed readout circuit is designed and fabricated using a 65 nm CMOS process. The readout IC achieves 100 dB of dynamic range in current sensing system by adaptively controlling the frequency of operating clock.
关键词： photodiode,current to PWM converter,trans-impedance amplifier,pulse-width modulation,CMOS,optical sensor
更新于2025-09-11 14:15:04
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A Liquid Pendulum Based Optical Tilt Sensor
摘要： In this paper a simple, low-cost single axis optical tilt sensor is presented. The presented sensor body is a transparent, cube shaped container made of an acrylic sheet. Additionally, it is half filled with liquid (i.e. water) based on its inner volume. In order to sense the liquid column inclination during the tilting of the sensor body, two pairs of optical trans-receiver have been used and their unique orientation across the sensor body claims relatively high measuring range. The basic working principle of the sensor depends on Snell’s law of refraction and reflection. Experimentally, it is observed that the developed prototype is able to sense the tilt angle in the range of ±90°, but a significant linear range is found in ±20°. In this range, the sensor has a resolution of 0.02° and sensitivity of 225mV/°.
关键词： optical sensor,Inclination,liquid pendulum,refraction of lights,tilt,Snell’s Law
更新于2025-09-10 09:29:36