Sensors

Single-Photon Avalanche Didoe and its Application on Light Detection and Ranging [ 下載 PDF ]

Sheng-Di Lin, Chia-Ming Tsai, Wei-Syun Huang, Tai-Hsiang Liu, Dai-Rong Wu

Excellent device performance, easy integration with circuits, and low-cost CMOS single-photon avalanche diodes (SPADs) for weak light detection attract application studies on bio-medical monitoring, substance identification, optical ranging, and quantum communication. This paper begins with device operation principle to explain its performance parameters subsequently. Finally, the advantages of using SPADs for light detection and ranging in vehicles and our related results are presented.

Magnetic Induced MEMS Biochip for Quality Inspection of Raw Milk [ 下載 PDF ]

Wei-Chen Li, Ching-Fu Tsou

In determining the degree of mastitic infection in raw milk, the somatic cell count (SCC) is the most widely accepted criterion that is used to quantify milk quality. A higher SCC can significantly reduce milk yield and increase treatment costs, so milk testing and quality control are essential if the milk processing industry is to protect raw milk from the risk of contamination by bacteria and other substances. For this, this article presents a novel inspection method that uses dual-coil inductance to evaluate the quality of raw milk. The device principally contains a silicon-based chip with two co-planar coils, which is fabricated using a simple microelectroplating process. When the coils are entirely immersed in raw milk and a specific alternating electrical signal is applied to one of the coils, the other coil induces a phase-shifted electrical signal because of the effect of eddy currents. Using the phase variation between both coils, the quality of the raw milk, in terms of the SCC (kcells/mL), can be evaluated. In this study, the characteristics of the magnetic inductance for a specified coil design and its sensing performance are simulated and evaluated using COMSOL software and by experiment. The experimental results show that higher SSCs cause larger phase shifts. This shift increases as the excitation frequency is increased. For a typical fabrication result, using a sensing coil with 25 loops, the measurement sensitivity in terms of SCC is 3°/log (SCC) at an excitation frequency of 9 MHz. The proposed dual-coil chip reduces size and cost and has a rapid response, which allows efficient quality inspection of raw milk.

The Integration of the Capacitive and Resistive Sensors with the Readout Circuit Systems [ 下載 PDF ]

Tsung-Heng Tsai, Yu-Chi Cao

The design and research of integration both capacitive/resistive sensors and readout circuit on a CMOS chip is described and organized as follows: First part is the introduction of capacitive/resistive sensors; Integration of sensors and readout circuits realizied by MEMS and CMOS technique is described in the second part; The third part describes the design flow of capacitive/resistive sensing chip; And the last part is the experimental results of a capacitive sensing chip.

Loading Effect-Induced Broadband Perfect Absorber Based on Single-Layer Structured Metal Film [ 下載 PDF ]

Keng-Te Lin, Hsuen-Li Chen, Yu-Sheng Lai, Chen-Chieh Yu, Yang-Chun Lee, Pao-Yun Su, Yu-Ting Yen, Bo-Yi Chen

In this study, we demonstrated a broadband perfect absorber based on loading effect-induced single-layer/trenchlike thin metallic (LISTTM) structures. These LISTTM structures take advantage of both surface plasmon resonance (SPR) phenomenon and three dimensional (3D) cavity effects to provide efficient, tunable, and polarizationinsensitive absorption from the UV to the infrared (IR) regime. The optimized hole-width of the LISTTM arrays was approximately one half of the designed wavelength. Therefore, even when the designed absorption band was in the visible regime, the feature sizes of the LISTTM structure could remain on the order of several hundred nanometers-dimensions much larger, and structures much simpler, than those of metamaterial-based absorbers. Besides, these LISTTM structures exhibited superior photothermal performance; they also displayed very low emissivity, thereby decreasing heat dispersion through thermal radiation. Therefore, the LISTTM arrays could efficiently absorb light of higher photon energy in the UV, visible, and near-IR regimes, effectively conduct and collect the generated heat through the continuous metal films, and barely disperse any heat through thermal radiation. Accordingly, these attractive properties suggest that such LISTTM absorbers might have promising applications in many fields related to energy harvesting.

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Development and Application of Electron Tomography at Atomic Resolution [ 下載 PDF ]

Liu-Gu Chen, Fu-Rong Chen

In this article, we introduce an atomic resolution tomography method using electron holography reconstructed from Cs corrected electron microscope. This method is allowed for quantitative analysis of three-dimensional atomic structure and surface topography from only one projected direction. Recently, TEM has capability to analyze material with sub-Å resolution with a Cs corrector. However, the real structure in three dimensions (3D) and the whole shape of material still can not be directly revealed from electron micrographs due to the limitation of two dimensional projected image. Certainly, materials properties can be corrected with the atomic arrangement in three dimensions. The ultimate goal of electron microscopy is to act as a communication channel between structure and properties of materials. It is therefore a very important issue how to determine the atomic positions in three dimensions from two dimensional projected images. We demonstrated our methodology using the simulated exit wave functions of a bilayer graphene, oleic acid molecules and experimental cases including of Ge nano-crystal, MgO and nano Au bridge.

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Ag/graphene/TiO₂ Composite Nanorods for Plasmonic Photocatalytic Reaction [ 下載 PDF ]

Hung Ji Huang, Shi-Yuan Zhen, Ping-Yu Li, Shien-Der Tzeng, Hai-Pang Chiang

Hot electrons is generated in nanorods of layered Ag/graphene/TiO₂ structure with high efficiency and presented to enhance plasmonic photocatalytic water treatment. The high-energy hot electrons generate under external lightillumination on titanium dioxide (TiO₂) nanoparticles lead to the conversion of oxygen molecule (O₂) to the highlyactive superoxide radical (*O₂⁻) that leads to the degradation of organics in water. However, the generated hot electrons tend to recombine with the simultaneously generated hot holes and convert to wasted energy. Graphene has lower energy level than Ag and TiO₂, and can keep the generated hot electrons from recombination with the generated hot holes. The experimental results of photocatalytic degradation of methyl blue presented the enhanced processing efficiency with the introduction of graphene layer.

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Development of Confocal Displacement Sensor System with Varifocal Lens [ 下載 PDF ]

Tzu-Hsien Lan, Zheng-Jie Ye, Bo-Rong Lu, Pi-Ying Cheng, Chun-Jen Weng

In this research, a special varifocal-lens was equipped into the displacement sensor, which provided the ability of varifocal length in measurement. Using the feature of different driven currents that differs the varifocal length rapidly, it replaces the traditionally confocal measurement that depends on the vertical movement in z-axis. It not only reduces the complexity of components and cost, but also avoids the error caused by z-axis motion.

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Introduction to Atomic Electron Tomography [ 下載 PDF ]

Chien-Chun Chen

Electron microscopy with the high resolution in planar images has found wide application in materials science and structural biology. Tomography has also made a revolutionary impact of non-destructively revealing threedimensional (3D) structures, especially in clinical medical imaging. Digital signal processing is applied to a broad range of electrical engineering to extract the information from noisy signals. Imperfections inside the crystalline structures have caught material scientists' eyes due to the capability of significantly changing properties of materials. A remarkable advance in the field of electron tomography has been made by combining several novel techniques: scanning transmission electron microscopy with annular dark-field detector to obtain high-resolution two-dimensional projection images, the center of mass alignment method to solve the misalignment problem, the equally sloped tomography method to achieve best spatial resolution by alleviating the missing wedge problem, and the 3D Wiener filtering to enhance the signal-to-noise ratio. With these combinations, a 2.4-angstrom resolution in the 3D reconstruction is demonstrated. Atomic steps and dislocations at the grain boundary inside a 10 nm platinum particle are observed. In the most recent developments, three-dimensional coordinates and chemical species of individual atoms are obtained to calculate the strains and magnetic properties of materials. This powerful technique has raised a great potential for applications to structural and functional materials.