High Sensitivity Micro Research Articles

High Sensitivity Micro Fiber Fabry Perot Pressure Sensor Based on Silicon MEMS Technology

High Sensitivity Micro Fiber Fabry Perot Pressure Sensor Based on Silicon MEMS Technology

High Sensitivity and Wide Dynamic Range Thermoresistive Micro Calorimetric Flow Sensor With CMOS MEMS Technology

In this paper, a thin film based Thermoresistive Micro Calorimetric Flow (TMCF) sensor by using a $0.35~\mu \text{m}$ 2P4M CMOS MEMS technology is designed, fabricated and tested. The developed $1.6~\mu \text{m}$ thick thin film CMOS TMCF sensor shows a maximum normalized sensitivity of 103 mV/(m/s)/mW with respect to the input heating power and a wide dynamic flow range of 0 ~ 19.4 m/s. The high sensitivity and wide dynamic range achieved by our CMOS MEMS flow sensor enable its deployment as a promising sensing node for HVAC application in the smart energy-efficient building (EeB). Moreover, a new one-dimensional (1D) analytical sensor model that considers the three-dimensional (3D) heat loss via the end of the thin film is proposed. The new 1D model can successfully capture the thin film based TMCF sensor’s response, and its prediction results show a good agreement with the experimental study. Therefore, this new 1D model will be a useful design tool for the development of a high-performance TMCF sensor with a greatly reduced footprint.

A High Sensitivity Micro Impedance Sensor Based on Magnetic Focusing for Oil Condition Monitoring

A high sensitivity micro impedance sensor is presented for oil condition monitoring. The sensor consists of a microfluidic chip and a sensing unit. The sensing unit contains two solenoid coils and eight silicon steel tips, which can generate a highly focusing magnetic field. The micro impedance sensor can not only distinguish between ferromagnetic and non-ferromagnetic metal particles, but also water droplets and air bubbles in oil. The simulation results show that the magnetic induction is significantly improved due to the silicon steel tips, and the electric field intensity is also slightly enhanced. In the inductance experiments, the sensitivity is extremely improved based on magnetic focusing by silicon steel tips, iron particles with diameters down to $18\mu $ m and copper particles with diameters down to 75 $\mu \text{m}$ have been successfully detected by using the simple high sensitivity micro impedance sensor. In the capacitance experiments, the signal to noise ratio (SNR) of the micro impedance sensor with silicon steel tips is slightly improved; water droplets with diameters down to 100 $\mu \text{m}$ and air bubbles with diameters down to 200 $\mu \text{m}$ have been detected. The high sensitivity micro impedance sensor has been demonstrated to achieve the precise measurement of particle sizes and the accurate counting of microparticles.

Design and implementation of high sensitivity micro spectrometer based on area array CCD

The area array CCD has the advantages of high sensitivity and wide dynamic range, which is suitable for fluorescence measurement, DNA sequencing, Raman spectroscopy and low photometric detection. Therefore, it is of great practical value to develop high sensitivity micro fiber spectrometer based on area array CCD. The optical resolution of 1 nm is obtained by using an optimized cross-asymmetric Czerny-Turner optical system structure. By combining the design methods of DC-DC and LDO, the complex power system with 6 voltage outputs is realized through USB power supply. The CCD drive timing design is achieved by Verilog HDL language and the signals are output through Altera's EPM7064 chip. After the CCD output video signal is converted by high-speed 16 bit AD chip AD9826, digital signals are stored in a separate static RAM, allowing dacquisition and reading of data to be separated. The sensitivity of designed micro-high sensitivity spectrometer is 11 times of that of spectrometer based on linear array CCD. Furthermore, it has a dynamic range of 20000: 1 and a signal-to-noise ratio of 500: 1. This work greatly improves the microfiber spectrometer performance.

Low-light-level readout of a new quantum dots sensor at room temperature

ABSTRACTIn this paper, we present an approach for low-light-level detection based on quantum dots and quantum well(QW) hybrid structure sensor operating at room temperature. The photodetector has AlAs/GaAs/AlAs double barrier structures with a layer self-assembled InAs quantum dots(QDs) and In0.15Ga0.85As QW. The photodetector shows high sensitivity to weak light irradiation and the operating temperature at 300 K. Its photoexcited carrier multiplication factor can reach about 2.35 × 106 at 0.01 picowatts (pW) 632.8 nm light power and −0.5 V bias. And the response voltage is 7−mV at integration time 80 μs. This high multiplication factor is achieved by the InAs QDs and In0.15 Ga0.85As QW induced photovoltaic effect. A high sensitivity micro spectrometer based on the 64 pixels QDs photodetector linear array was developed. The novel micro spectrometer was used to investigate the biological sample. The test results show the spectrometer based on QDs photodetector has higher sensitivity contrast with commercial spectrometer. The high sensitivity features of the spectrometer make it a promising choice for Raman or fluorescence detection.

Study of a novel pressure sensor based on optical microring resonator

We propose a novel pressure sensor based on the combination of the ring resonator with two straight waveguides and a two-end fixed beam. The principle of this device is acquiring the system static pressure by monitoring the changes in the transmission wavelength shift of the ring resonator with double waveguides. The numerical results show that the sensitivity of the system is up to 49.3 pm/kPa while the pressure range is 0-300 kPa. The thickness of the fixed beam is an important factor which impacts the sensitivity of the system. This device can provide support for fabricating high sensitivity and low cost micro pressure sensors.

J2230205 磁気駆動型マイクロ電流センサの研究([J223-02]マイクロナノメカトロニクス(2),マイクロ・ナノ工学部門一般セッション)

In this study, to obtain knowledge necessary to establish research direction in developing high sensitivity and low power consumption micro current sensors, we investigated the sensor output of a micro current sensors consisted of a cantilever equipped with a piezoelectric film (PVDF) and a soft magnetic material (Fe). From the viewpoint of structure science, the research results indicated that the sensor output rapidly increases at the resonant frequency. Furthermore from the viewpoint of materials science, it revealed that careful shape design to align magnetic moments is inevitable to employ large magnetization of the soft magnetic materials to increase the sensor output.

Incorporation of beams into bossed diaphragm for a high sensitivity and overload micro pressure sensor

The paper presents a piezoresistive absolute micro pressure sensor, which is of great benefits for altitude location. In this investigation, the design, fabrication, and test of the sensor are involved. By analyzing the stress distribution of sensitive elements using finite element method, a novel structure through the introduction of sensitive beams into traditional bossed diaphragm is built up. The proposed configuration presents its advantages in terms of high sensitivity and high overload resistance compared with the conventional bossed diaphragm and flat diaphragm structures. Curve fittings of surface stress and deflection based on ANSYS simulation results are performed to establish the equations about the sensor. Nonlinear optimization by MATLAB is carried out to determine the structure dimensions. The output signals in both static and dynamic environments are evaluated. Silicon bulk micromachining technology is utilized to fabricate the sensor prototype, and the fabrication process is discussed. Experimental results demonstrate the sensor features a high sensitivity of 11.098 μV/V/Pa in the operating range of 500 Pa at room temperature, and a high overload resistance of 200 times overpressure to promise its survival under atmosphere. Due to the excellent performance above, the sensor can be applied in measuring the absolute micro pressure lower than 500 Pa.

A Design of Micro Magnetic Detection and Localization System

Magnetic detection and localization is becoming a hot point in the past twenty years. Amorphous wire is a promising material to produce high performance magnetic sensor for GMI effect. A high sensitivity micro magnetic sensor is designed and a processing circuit is presented in this paper. Based on the processor TMS320F28335, the magnetic signal of ferromagnetic target can be sampled and processed.

Novel device for calibration-free flow rate measurements in micro gas chromatographic systems

Accurate knowledge of flow rate is critical when quantifying analytes in a chromatographic separation. Using the flow rate, the area of a peak and the response factor of a detector one can calculate the total quantity of the analyte being examined. To date, this quantification has not been possible since no in situ method for flow rate detection within a detector existed. We have developed and tested a novel device and method for measuring the linear flow rate in a micro-gas chromatography (GC) system. Our design utilizes a high-sensitivity micro thermal conductivity detector (μTCD), which is capable of replacing a traditional TCD and requires no calibration for the precise measurement of flow rates. Furthermore, this measurement occurs exactly where the solute elutes from the GC separation column, the point at which knowledge of flow rate is most critical for analyte quantification. To the best of our knowledge, no other method of measuring the flow rate directly at the sensor currently exists.

SU‐FF‐T‐339: Small Field Electron Beam Dosimetry Using MOSFET Detector

Purpose: The dosimetry of very small electron fields can be challenging due to relative shifts in percent depth‐dose curves, including the location of dmax, and lack of lateral electronic equilibrium in an ion chamber when placed in the beam. Conventionally, a small parallel plate chamber or film is utilized to perform small field electron beam dosimetry. With the advent of electronic imaging, modern radiotherapy departments are moving to a filmless environment and an alternate clinical dosimeter is required for routine clinical dosimetry. In this work, we have studied the performance of MOSFET as a relative dosimeter for small field electron beams. Methods and materials: The reproducibility, linearity and sensitivity of a high sensitivity micro MOSFET were investigated for clinical electron beams. In addition, the percent depth doses, output factors and profiles have been measured in a water tank with MOSFET and compared with those measured by an ion chamber and film for a range of field sizes from 1 cm diameter to 10×10 cm2 for 6, 12, 16 and 20 MeV beams. Similar comparative measurements were also performed with MOSFET as well as with films in solid water phantom. Results: The MOSFET sensitivity was found to be stable over the range of field sizes investigated. The dose response was found to be linear and reproducible (within ±1% for 100 cGy). For 1, 1.5, 2, 2.5, 3, 4, 5, 6 cm circular and 10 cm square field, excellent agreement (within ±2% and ±2mm) was observed among the central axis depth dose curves measured using MOSFET, film and ion chamber. The output factors measured with MOSFET for small fields agreed to within 2% with those measured by film dosimetry. Conclusion: Overall results indicate that MOSFET can be utilized to perform dosimetry of small electron fields for routine clinical use.

Micro Capacitive Tactile Sensor for Contact Loads

This paper presents a high sensitivity micro capacitive tactile sensor that can detect normal forces which is fabricated using deep reactive ion etching (DRIE) bulk silicon micromachining. The tactile sensor consists of a force transmission plate, a symmetric suspension system, and comb electrodes. The sensing character is based on the changes of capacitance between coplanar sense electrodes and it can reach the aim of large sensing range. High sensitivity is achieved by using the high aspect ratio comb electrodes with narrow comb gaps and large overlap areas. In this paper, the sensor structure is designed, the capacitance variation of the proposed device is analyzed, and the finite element analysis of mechanical behavior of the structures is performed.

Study on a Resonance Type Micro Acceleration Sensor (1st Report)

Sensors that detect the mechanical quantity are shifting from the bulk type to the MEMS type for the miniaturization, the cost reduction, and high reliability.1)∼4) Regarding the acceleration sensor, the resistance type and the capacitance type made by the MEMS technology have been commercialized. However, the sensitivity is still a weak point to those sensors. It is considered that there is an advantage of sensitivity in the resonance type because the mechanical resonance is used. In this study, we clarified the relation between sensitivity and the size concerning the newly designed resonance type acceleration sensor by the numerical simulation. Next we evaluated the sensor characteristics with the 20-times enlarged model. As a conclusion, it was confirmed that the resonance type had a potential for realizing the high sensitivity micro acceleration sensor.

Current density effect on magnetic properties of nanocrystalline electroplated Ni 80Fe 20/Cu composite wires

In developing high-sensitivity micro sensors for very weak magnetic field, extremely high permeability magnetic material is essential for the sensing element. In this study, the effect of plating current density in nanocrystalline electrodeposition of permalloy on the crystal grain size and consequently on the soft magnetic properties of the deposited layer of Ni 80Fe 20/Cu composite wire is investigated. It is found that the coercivity of the deposited Ni 80Fe 20 increases and the MI effect ratio of the Ni 80Fe 20/Cu wire decreases with increasing current density in the lower range of current density (0.6–2 A/dm 2) while the opposite trend is observed as the current density range increases in a higher range (2–8 A/dm 2). It seems that increasing plating current density has the effect of decreasing the crystal grain size of the plated material, resulting in lower coercivity of the plated material. This effect, due to decreased grain size, is dominating in the higher range of plating current density. However, it also has the effect of increasing residual stresses in the plated material, which is dominating in the lower range of plating current density, resulting in higher coercivity of the plated materials.

Effect of Magnetic Field on the Magnetic Structure of Nanocrystalline Electroplated NiFe Layers

In order to develop high sensitivity micro sensors for bio-magnetic field using NiFe electroplated composite sensing elements, it is important to study how different plating processes can affect the magnetic properties in terms of the chemical composition and magnetic structure of the plated layer. In this study, to study the effect of the magnetic field on the magnetic structure of the electroplated NiFe layers, magnetic controlled plating in which a longitudinal magnetic field ranging from 0 to 400 Oe is applied during nanocrystalline electroplating of permalloy Ni80Fe20 layer of 2 µm thick onto a 20 µm diameter Cu wire. The magnetic structure of the plated layers is studied by investigating the Giant magneto-impedance (GMI) effect of the plated layer. GMI has been measured from a frequency range of 100 kHz to 50 MHz. It is observed that under conventional electroplating without an external magnetic controlling field, the anisotropy of the plated layer is generally circumferential as indicted by the double peaks of the MI curves in testing at high frequency. When a longitudinal magnetic field is applied during electroplating, the plated layer shows single peak MI curves, suggesting that the anisotropy is changed from circumferential to longitudinal. The results also show that the sensitivity and resolution of a magnetic field sensor is improved greatly by changing the anisotropy of the plated layer from circumferential to longitudinal.

Thermodynamics of the interaction of some chloro- and fluoro-substituted alcohols with bovine α-lactalbumin

The temperature dependence of the excess heat capacity and evaluation of thermodynamic parameters of bovine α-lactalbumin has been studied by high-sensitivity micro differential scanning calorimetry in the presence of 4-chlorobutan-1-ol, n-butanol, 3-chloropropan-1-ol, 3-chloropropan-1,2-diol, propan-1,2-diol, n-propanol, 2,2,2-trifluoroethanol, and ethanol at neutral pH. The chlorosubstituted alcohols are observed to be more effective destabilisers of α-lactalbumin compared with their normal alcohols in the order: 4-chlorobutan-1-ol > n-butanol > 3-chloropropan-1-ol > n-propanol > 2,2,2-trifluoroethanol > 3-chloropropan-1,2-diol > ethanol > propan-1,2-diol. A reversible two-state approximation for the unfolding of the protein has been shown in the absence and presence of these alcohols. A second, smaller, endothermic transition, 23°C beyond the main endotherm was observed only in the presence of 0.125 to 0.250 mol dm-3 3-chloropropan-1-ol. Concentrations higher than 25 mmol dm-3 4-chlorobutan-1-ol resulted in total loss of an observable endotherm. Thermal destabilisation of the protein in these solvent systems is explained on the basis of competing patterns of interactions of the cosolutes with the native versus unfolded states of the protein during the nativedenatured reaction. These results are supported by intrinsic fluorescence, energy transfer and UV difference measurements.

Packed-capillary liquid chromatography/ion-spray tandem mass spectrometry determination of biomolecules

Precolumn flow splitting is successfully implemented for gradient separation in peptide-mapping applications with a column internal diameter of 320 μm. Peptide standards, protein tryptic digests, and a crude peptide mixture from industry are used to demonstrate the feasibility for utilizing the packed-capillary LC/MS system in a variety of applications. High-sensitivity micro LC/MS peptide mapping and molecular weight determination can be performed routinely via ion-spray LC/MS with injected sample amounts as low as 10 pmol. Peptide sequence information is obtained via on-line packed-capillary LC/MS/MS

High-sensitivity micro ultraviolet absorption detector for high-performance liquid chromatography

A UV absorption detector with a 0.6-μl flow cell for high-performance liquid chromatography (HPLC) was developed. In order to improve the signal-to-n