Sensor Design Parameters Research Articles

A Parametric Design Study of an Electrochemical Sensor

The development of highly sensitive biosensors for the detection of biomolecules, such as the biomarker interleukin-8 for the early detection of oral cancer, requires optimization of sensor design. To augment the performance of an electrochemical sensor, this study used a microscale, aptamer-based electrochemical sensor for detecting botulinum neurotoxin aptamer hybridization. We first used top—down lithographic processing to define the pattern of the electrodes and then used bottom—up manufacturing to modify the surface molecular properties for reducing nonspecific binding. We systemically examined the effects of the design parameters of an aptamer-based electrochemical sensor. Specifically, five key design parameters were examined: the area of the working electrode (WE), the area of the counter electrode (CE), the separation distance between the WE and CE, the overlap length between the WE and CE, and the aptamer concentration. Through an analysis of the signal and noise generated across variations of the different parameters, the significance of each parameter in sensor performance was determined. In particular, we found that the area of the WE was the only key parameter that influenced the performance of the sensor. The output signal level increased with the area of the WE and the signal-to-noise ratio was about constant in the tested range (i.e., from 0.02 to 4 mm2).

높은 동적영역을 갖기 위한 정전용량형 센서의 최적화

The capacitive sensor has a simple structure, compact size and low cost, but a small dynamic range. The small range is caused by use of gap variation. If the sensor takes area variation type with one plate moving horizontally, it can have a large measurable range. While the area variation has relatively low sensitivity, some studies have found methods to improve the sensitivity. Even though the methods are effective, parameters of the results are limited and 2 dimensional. This study provides more practical and 3 dimensional analysis and suggests relations between parameters. Using the results, the optimized design parameters of a high dynamic range capacitive sensor can be found.

Infrared sensor modeling for human activity discrimination tasks in urban and maritime environments

The United States military is increasingly using infrared (IR) sensors to discriminate the actions and intentions of people being observed in an area of interest; however, there is currently inadequate modeling capability to a priori determine the effectiveness of IR sensors for these types of tasks. The U.S. Army's NVTherm model is a military and industry standard sensor performance model that estimates target acquisition performance based on both the sensor design parameters and an empirically measured calibration factor to represent human observer performance. Historically the model has been calibrated by presenting static imagery to observers and measuring average probabilities of accomplishing the given task. The task of human activity discrimination, however, presents new challenges to the model, as "activity" inherently implies a dynamic scene where motion cues are essential in accomplishing the task. A series of studies has been completed in order to calibrate NVTherm for the task of human activity discrimination. The challenges involved in representing the human activity task, the establishment of new processing methods, and new standards for defining simple target metrics for complex imagery are discussed. The experiments that have supported the calculation of new calibration parameters are also described. These efforts have brought the U.S. Army significantly closer to having a sensor performance model validated for discriminating human activity with IR sensors.

Sensitivity analysis of packaging effect of silicon-based piezoresistive pressure sensor

The silicon-based pressure sensor is one of the major applications in the MEMS device. Nowadays, the silicon piezoresistive pressure sensor is a mature technology in the industry, but its requirement in terms of sensing accuracy and stability is more rigorous than that of many advanced applications. The major factor affecting the sensing stability of the piezoresistive pressure sensor is its thermal and packing effects. For a packaged pressure sensor, silicone gel is usually used to protect the die surface, so the thermal and packaging effects caused by the silicone gel should be taken into consideration to obtain better sensing sensitivity and stability. For fast design and optimization purpose, a finite element method (FEM) is adopted for sensor performance evaluation, packaging-induced signal variation, and thermal/packaging effects will be examined in this research. Several experiments are also performed to validate the finite element model. After the simulation is validated, an optimization analysis is carried out under different packaged pressure sensor design parameters. The simulation results show that the different geometry of the protection gel will influence pressure sensitivity significantly; base on analysis results, this research will conclude a design guideline for pressure sensor packages with concave and convex type of protection gel.

Design considerations for surface plasmon resonance-based fiber-optic detection of human blood group

A fiber-optic surface plasmon resonance (SPR) sensor for the detection of human blood groups is proposed. Previous experimental results describing the wavelength-dependent refractive index variation of multiple samples of different blood groups are considered for theoretical calculations. The spectral interrogation method, along with silica fiber and silver layer, is considered. The sensor's performance is closely analyzed in terms of shift in SPR wavelength and SPR curve width in order to optimize the design parameters for a reliable and accurate blood-group identifier. The sensor design parameters include silver layer thickness, fiber core diameter, sensing region length, and temperature variation. The results are explained in terms of light coupling and plasmon resonance condition. The proposed sensing probe is able to provide high sensitivity and accuracy of blood-group detection, thereby opening an easy and reliable window for medical applications.

Optimized fiber optic bioprobe with high spectral contrast exploiting laser-induced fluorescence for malignancy diagnosis

A high spectral contrast is expected to be very important when laser-induced fluorescence (LIF) is employed for cancer diagnosis. We developed a LIF optical fiber sensor to achieve a very high spectral contrast between normal and malignant tissues. A comprehensive experimental investigation was carried out to study the role of two critically important parameters for sensor design, namely, the excitation-collection geometry and the excitation wavelength, and their effect on the autofluorescence spectral contrast. An optimum sensing configuration was determined in order to enhance the small, but consistent, spectral difference between the normal and the malignant tissue for improving the accuracy of LIF-based cancer diagnosis. With the optimum sensor configuration, we realized a spectral contrast of more than 22 times between normal and malignant tissue sample spectra.

Parametric design of yarn-based piezoresistive sensors for smart textiles

In our previous paper, the yarn-based sensors are shown capable of measuring the respiration signals. In comparing with fabric-based sensors, the yarn-based sensor is more comfortable in wearing, and easily fabricated by conventional textile process. In this paper, we aim at the analysis of the design parameters of the yarn-based sensors that were fabricated by double wrapping the polyester, elastic, and piezoresistive fibers. The performances of the yarn-based sensor under different compositions have been experimentally evaluated. It is shown that the soft-core yarn sensors achieve high gain factors with low linearity. The sensors consisting of high-density piezoresistive fibers achieve high linearity with low gain factor. It was also shown that the nonlinearity of the sensors that is mainly due to the irregular characteristics of the yarn structure exits at the low strain region. As at the high strain region, the high linearity of the yarn-based sensors is found regardless of material compositions. To further reduce irregular characteristics of the yarn structure, to increase the preload and to choose the stiffer core yarn and the harder piezoresistive fibers are suggested.

Design and Simulation of a Tactile Sensor for Soft-Tissue Compliance Detection

A detailed design procedure for a tactile sensor for compliance detection is developed. The sensor principle is based on the concept of applying two springs, with considerably different stiffnesses, to soft tissue for compliance detection. The spring stiffnesses are chosen to be associated with the soft tissue properties. The sensor design parameters are optimized to give high sensitivity and linearity of the sensor output with taking into account the effect of crosstalk between two springs due to the tissue deformation. A finite element model is developed to investigate the sensor performance with the designed parameters using two types of spring end, namely cubic and spherical in shape. The results show a significant stability of reading with the cubic end rather than the spherical one during pushing the sensor against a tissue. Finally, the same finite element model is used with changing the distance between the spring ends to show the crosstalk effect due to the tissue deformation.

Design optimization of a long-period fiber grating with sol–gel coating for a gas sensor

The design of a novel scheme long-period fiber grating (LPFG) film sensor is presented. The sensor is composed of a long-period grating coated with sol–gel derived films, which are sensitive to the surrounding medium (gases). Based on the coupled-mode theory, a four-layered numerical model has been developed to study the characteristics of the transmissivity of the LPFG film sensor. By analyzing the relationship between the sensitivity Sn and the thin film optical parameters (thickness h3 and refractive index n3) and the fiber grating parameters (the grating period Λ, the core index change σ and the grating length L), the optimal design parameters of the LPFG film sensor can be obtained. Data simulation shows that the resolution of the refractive index of this LPFG film sensor is predicted to be 10−8. Experimentally, a long-period fiber grating film sensor for the detection of C2H5OH was fabricated, and a preliminary gas-sensing test was performed. The results indicate that a novel optical film sensor scheme with structure optimization has higher sensitivity.

Influence of design parameters of ECT sensors on the quality of reconstructed images

The configuration of electrodes and guards, as well as the shielding arrangement, determines the resolution and sensing field of an ECT sensor. In this work, a full study of the response of a 12-electrode sensor is carried out by means of 2D and 3D Finite Element Method based simulations, and the influence of the design parameters on the sensitivity and quality of the reconstructed images is stated.

ANALYSIS AND TRADE-OFF STUDY OF SIGNAL-TO-NOISE RATIO DEPENDENT DESIGN PARAMETERS OF SATELLITE PASSIVE ELECTRO-OPTICAL REMOTE SENSORS

One of the main goals that is concerned to remote sensor designers is the quality of the produced image. There are a number of parameters to evaluate the quality of the image produced by an imaging sensor. The parameters widely used are the Modulation Transfer Function (MTF) and signal-to-noise ratio (S/N), for passive electro-optical remote sensors. In this paper an analysis and trade-off study of S/N dependent sensor design parameters are presented.

Monitoring the displacements of movable lenses in the projection objective of a photolithographic system for producing superlarge integrated microcircuits

This paper describes structurally integrated capacitive sensors that measure the displacement and tilt angles of the movable mount of the lens module of a system for compensating the image-scale variations caused by thermobaric misalignment of a photolithographic projection objective. We present a technique for choosing the optimum design parameters of capacitive sensors, an algorithm for calculating the displacement and tilt angles from the measured capacitance values of the sensors, and a rough calculation of the error and of the measurement for various displacement ranges.

Power consumption analysis of surface acoustic wave sensor systems using ANSYS and PSPICE

The power consumption of a surface acoustic wave (SAW) sensor system was investigated using ANSYS and PSPICE. Simulation results show that several design parameters of the surface acoustic wave sensor, such as the center distance between two interdigital transducers (IDT), the thickness of the piezoelectric substrate, the finger space of the IDT, etc., can greatly affect the power consumption of the whole system. The results of this study will be helpful to optimum design and fabricate the SAW sensor systems with very low-power consumption.

Optical fiber long-period grating with solgel coating for gas sensor

The novel long-period fiber grating (LPFG) film sensor is composed of the long-period grating coated with solgel-derived sensitive films. The characteristics of the transmissivity of the LPFG film sensor are studied. By analyzing the relation among the sensitivity Sn, the thin film optical parameters, and the fiber grating parameters, the optimal design parameters of the LPFG film sensor are obtained. Data simulation shows that the resolution of the refractive index of this LPFG film sensor is predicted to be 10(-8). Experimentally, a LPFG film sensor for detection of C(2)H(5)OH was fabricated, and a preliminary gas-sensing test was performed.

SOIL FAILURE MODELS FOR VERTICALLY OPERATING AND HORIZONTALLY OPERATING STRENGTH SENSORS

Soil strength, or mechanical resistance of a soil to failure, has been widely used to estimate the degree of soilcompaction. Conventional measurements with cone penetrometers are laborious; therefore, an on-the-go soil strength profilesensor that collects data dense enough to show the spatial within-field variability in soil strength would be a desirablealternative. Because soil failure involves complex interactions among many variables, determining design parameters of asoil strength sensor and interpreting test results could be improved with a theoretical understanding of the soil failure process.Mathematical models to estimate the force required to penetrate (cut and displace) soil with a prismatic cutter travelinghorizontally and with a cone penetrometer traveling vertically were developed based on the passive earth pressure theory andthe concept of a variable failure boundary. Both models were expressed as additive forms of density, cohesion, and adhesioncomponents of the soil, with each effect multiplied by a corresponding dimensionless number. Charts of dimensionlessnumbers were developed to investigate the behavior of each strength component at various values of soil internal frictionangle, soil-metal friction angle, and tool cutting angle. The models were used in simulation to optimize design parametersof the sensor, including component dimensions and the location and spacing of sensing elements. Based on this optimization,a prismatic sensing tip with a 3.61 cm2 base area and a 60 cutting angle was selected, and the corresponding simulatedmaximum force and strength measurements were 2.2 kN and 6.0 MPa when operating at speeds up to 5 m s-1. Model validationshowed that the extension of the failure boundary was significantly correlated with soil properties such as bulk density, watercontent, and internal friction angle. The variable failure boundary model developed in this study more consistently andaccurately represented field data than did three previously developed modeling approaches.

Complete analytical modeling and analysis of micromachined thermoelectric uncooled IR sensors

This paper deals with a complete analytical modeling and analysis of thermoelectric uncooled infrared sensors compatible with CMOS technology. The operating principle involves a localized thermal assessment resulting from IR radiation absorption, a micromachined membrane on which PolySi/Al thermojunctions have been deposited causing an internal self-generated electromotive force. The model put forward is based on dividing the sensor into three zones, each one being the subject of a thorough thermal study (conduction, convection and radiation thermal effect). Through the analytical thermal gradient analysis developed in each zone of the structure (absorber, part of thermoelectric transducer layer placed under the absorber, thermoelectric transducer) we are able to predict the sensitivity, detectivity and the noise equivalent power to the sensor. Thus, such a kind of analytical approach is worth of interest to optimize thermopile sensor design parameters.

Analysis and validation of thermal and packaging effects of a piezoresistive pressure sensor

In this study, a packaged silicon base piezoresistive pressure sensor with thermal stress buffer is designed, fabricated, and studied. A finite element method (FEM) is adopted for designing and optimizing the sensor performance. Thermal and pressure loading on the sensor is applied to make a comparison between experimental and simulation results. Furthermore, a method that transforms simulation stress data into output voltage is proposed in this study, and the results indicate that the experimental result coincides with the simulation data. In order to achieve better sensor performance, a parametric analysis is performed to evaluate the system sensitivity, as well as thermal and packaging effects of the pressure sensor. The design parameters of the pressure sensor include membrane size, sensor chip size, glass thickness, adhesive layer thickness, PCB thickness/material, etc. The findings show that proper selection of the sensor structure and material not only enhances the sensor sensitivity but also reduces the thermal effects as well as the packaging influence.

Theoretical analysis of 2D acceleration laser sensor and several design parameters

Having adopted several sets of new technology and techniques, we have developed a new type of laser angle sensor that can be used to measure two-dimensional (2D) angle of moving target. On this basis, a new design for 2D acceleration laser sensor has been advanced. The optics-type sensor can be used to measure 2D acceleration of motion object, and it has high sensitivity, high precision and longer measuring range. Under these design parameters that are given in this paper, the measuring range will achieve 177 g , while its sensitivity is 13.5 s 2 . The experimental results show that the measuring error is not greater than 0.1 g . In this paper, several design parameters and measuring results for 2D acceleration laser sensor are given.

Theoretical analysis of 2D laser angle sensor and several design parameters

Having adopted several sets of new technology and techniques, such as cube-corner prism of higher refractive index, orthogonal holographic grating, non-linear compensation, and fringe fractionization, etc., we have developed a new type of laser angle sensor that can be used to measure two-dimensional angle of moving target. The sensor has high sensitivity, high precision and longer measuring range compared with the original sensor, and its measuring range will achieve ±35°, while its minimum resolution angle is 0.004°. The experimental results show that the measuring error is not greater than ±0.01°. In this paper, several design parameters and measuring results for 2D laser angle sensor are given.

Characterization of a WO 3 thin film chlorine sensor

A semiconducting metal oxide (SMO) gas sensor for the detection of chlorine has been developed and characterized. A WO 3 thin film has been used as the sensing element. The sensors were found to respond to sub-ppm chlorine concentrations by a reversible decrease in conductivity up to three orders of magnitude, depending on operating temperature and sensor design parameters such as electrode material. The influence of annealing on sensor performance is discussed. Several observations in the gas sensing experiments as well as preliminary X-ray photoelectron spectroscopy (XPS) results give some insight into the chemical and physical processes underlying the sensor response.