Browsing by Author "Hsu, WY"

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A micro membrane vibrator with thermally driven bimorph cantilever beams
(1997)
Tsao, CC
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Hsu, WY
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機械工程學系
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Department of Mechanical Engineering
A micro membrane vibrator consisting of bimorph cantilever beams and a membrane is designed, fabricated, and tested here. Due to the discrepancy of thermal expansion coefficients between different layers, the membrane moves with temperature change. The four-layer structure including SiO2-polysilicon-insulated SiO2-aluminum is fabricated with four masks. The numerical finite element program ANSYS 51 is used to investigate the behavior of different designs to have larger displacement and force. According to the testing results, we observe that our designs can induce the maximum Z-axis displacement up to 117 mu m when input power is 6.98 W. The working frequency is about 40 Hz when the amplitude is kept between 2 and 5 mu m approximately.
A microstructure for in situ determination of residual strain
(1999-06-01)
Pan, CS
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Hsu, WY
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機械工程學系
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Department of Mechanical Engineering
This work presents a new strain sensor with a compact structure. The strain sensor comprises of a pair of cantilever beams with different lengths connected by a short tip. The residual strain causes two beams to deflect each other, thereby magnifying the deflection, which is measured by the tip. The displacement is independent of both Young's modulus and the film's thickness. An analytical model is derived to relate the measured displacement to residual strain. Finite-element modeling is also used to analyze the model. This work also thoroughly considers other factors that influence the designs and the implicit limitations of the strain sensors. Experimental results with an SiO2 film as well as undoped LPCVD polysilicon films are used to demonstrate the effectiveness of the proposed structure.
An electro-thermally and laterally driven polysilicon microactuator
(1997-03-01)
Pan, CS
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Hsu, WY
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機械工程學系
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Department of Mechanical Engineering
A novel electro-thermally and laterally driven microactuator made of polysilicon has been designed, fabricated, and tested. The operational principle is based on the asymmetrical thermal expansion of the microstructure with different lengths of two beams, but not based on the variable cross sections of the microstructure. A microgripper to demonstrate one possible application of the microactuator is fabricated and characterized. The input voltage of this design is less than 10 dc to produce 20 mu m displacement with about 0.6 mJ heat dissipation, and the maximum temperature is less than 600 degrees C. A gripping force up to 2.8 mu N can be generated. Simulation results are compared with the experimental data and show good agreement. Some design parameters strongly influencing the performance of the microactuator are discussed also.
CMOS chip as luminescent sensor for biochemical reactions
(2003-06-01)
Lu, U
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Hu, BCP
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Shih, YC
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Yang, YS
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Wu, CY
We describe a novel biochemical sensing method and its potential new biosensing applications. A light-sensitive complementary metal oxide semiconductor (CMOS) chip prepared through a standard 0.5-mum CMOS process was developed for measuring biochemical reactions. A light producing enzymatic reaction catalyzed by horseradish peroxidase (HRP) was designed as a platform reaction to determine the concentration of hydrogen. peroxide (H2O2) by the CMOS chip with a standard semiconductor parameter analyzer (HP4145). The kinetics of enzymatic reaction were determined and compared with a standard and sophisticated fluorometer (Hitachi F-4500) in a biochemical laboratory. Similar results were obtained by both instruments. Using glucose oxidase as an example, we further demonstrated that the HRP platform can be used to determine other H2O2 producing reactions with the CMOS system. The result points to an important application of the CMOS chip in biological measurements and in diagnosis of various health factors.
Design and fabrication of an electrothermal microactuator for multi-level conveying
(2006-03-01)
Wu, CT
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Hsu, WY
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機械工程學系
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Department of Mechanical Engineering
During the past years, a variety of microactuators developed for micro-conveyors have been presented. However, such micro-conveyors can only provide conveying motion in a single plane. Here an electrothermally driven microactuator with a capability of adjustable height is proposed, which may act as a basic unit for multi-level conveyors. This microactuator is based on the principle of thermal bimorph actuation with two long conveying fingers to exert out-of-plane bending motions in the transversal direction, which are connected and lifted by an initially curved height adjuster in the longitudinal direction. The devices can provide conveyance of micro-objects between two plane levels of different heights. The testing results show that the two fingers and a height adjuster can be actuated simultaneously and individually with little thermal crosstalk. The proposed device with a dimension of 900x100x4.5 mu m(3) can provide 5 mu m vertical displacements by the height adjuster at 1 V and 18 mu m lateral displacements by the conveying finger at 2 V. Simulations by finite-element program ANSYS 5.7 have been performed and widely match with testing results.
Electrothermally driven long stretch micro drive with modlithic cascaded actuation units in ompact arrangement
(2003)
Hsu, CP
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Liao, TS
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Hsu, WY
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機械工程學系
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Department of Mechanical Engineering
An electrothermally-driven long stretch micro drive (LSMD) is presented for in-plane rectilinear motions in hundreds of micrometers with very compact arrangement. High output performance (output displacements over device area excluding electrical contact pads) of 200 mum/mm(2) has successfully achieved for devices made of 10similar to12 mum thick electroplated nickel. The proposed device (N=5) features large output displacements with low operation temperatures (< 350degreesC) and driving voltages (< 4 volts). It can be operated up to 100 Hz at 3 volts without displacement degradations. Experiments and simulations are conducted to verify two design issues, bent beam angle and constraint bar width, with good agreements. The output displacements can be effectively magnify by cascading more actuation units in cascaded structures of the micro drive.
Experimental investigation of an embedded root method for stripping SU-8 photoresist in the UV-LIGA process
(2004-03-01)
Ho, CH
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Hsu, WY
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機械工程學系
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Department of Mechanical Engineering
In much previous research it has been popular to use SU-8 photoresist as a mold for electroplating, facilitating the production of low-cost microelectromechanical systems. However, the thickness of the electroplated structures standing on the substrate could only reach 50 mum or less due to the internal force and deformation of the photoresist in the final stripping process. In order to fabricate thicker structures, an embedded root method has been proposed to consolidate the adhesion of the metal structures to the substrate during the SU-8 removal process. In this paper, an experimental investigation of this method is conducted to characterize the relationship between the root depth, the linewidth and the achievable thickness of the electroplated structures. Some test patterns with embedded roots have been designed and fabricated to estimate the possible size of various structures associated with different depths of niches, which are completely defined through the SiO2 masking and KOH etching processes. Based on the established relationship between the root depth and the geometric sizes, a three-dimensional Ni coil, with a thickness of 200 mum, a width of 80 mum and a root depth of 4 mum, is successfully released by the SU-8 mold, which has a height of 400 mum. This cannot be achieved by the standard SU-8 molding process. The process parameters presented herein may be applied to the fabrication of other thick metal microstructures with similar needs.
Influence of initial curvature effect on micromachined thermal bimorph actuation
(2001)
Hsu, CP
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Hsu, WY
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機械工程學系
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Department of Mechanical Engineering
While the micro bimorph structures are fabricated with enough initial curvatures or so-called geometrical imperfections, structural instability may occur to result in snap-through behaviors and exhibit large deflection strokes. The bimorph structures with various initial deflections ratios and various heating area ratios are simulated and fabricated to predict the stable and unstable regions of the curved bimorph structures with clamped boundary condition. Four major types of load-deflection curves are described and discussed. Testing results and some observations are reported.
Instability in micromachined curved thermal bimorph structures
(2003-11-01)
Hsu, CP
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Hsu, WY
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機械工程學系
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Department of Mechanical Engineering
For the micromachined thermal bimorph structure, there is often initial deflection, or so-called geometrical imperfection, which may affect the stability of the structure. Here, finite element simulations and experiments are conducted to study the influences of initial deflection and actuating region on mechanical behaviors of a curved bimorph structure with clamped boundary condition. Devices are fabricated by adjusting the internal stresses of polysilicon layers on bimorph structures to achieve various initial deflections. Various actuation regions are achieved by designing different sizes of top layers covering the bottom layers of the bimorph structures. Stable and unstable regions in terms of two design factors, initial deflection ratio and bimorph ratio, are characterized by simulations and experiments. It is found that the curved bimorph structure is stable when the bottom layer is fully covered with the top layer or the initial deflection is much smaller than the structure thickness. The stable device is found to deflect in one direction only. The bimorph structure becomes unstable while the initial deflection is close to or larger than structure thickness. For unstable curved bimorph structures, we find the snap buckling effect with two-way deflections and a hysteresis loop.
Modeling of a finger-follower cam system with verification in contact forces
(1996-03-01)
Hsu, WY
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Pisano, AP
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交大名義發表
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機械工程學系
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National Chiao Tung University
A lumped/distributed-parameter dynamic model is developed to investigate the dynamic responses of a finger-follower cam system by considering a hydraulic lash adjuster with an oscillating pivot, and frictional forces between sliding surfaces. The measured force data at low speed are employed to derive an algorithm to determine the dynamic Coulomb friction coefficients at contact points. The contact position between the earn and the follower with moving pivot is determined by a constraint equation method. A hydraulic lash adjuster acting as the pivot of the follower is also modeled with the effects of oil compressibility and oil refill mechanism. Simulated contact forces at three different speeds are shown to have good agreement with experimental data. The separation between the hydraulic lash adjuster and the follower is predicted at a camshaft speed of 2535 rpm, ana experiment indicates at 2520 rpm.
Modelling the static and dynamic behavior of a conical spring by considering the coil close and damping effects
(1998-07-02)
Wu, MH
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Hsu, WY
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機械工程學系
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Department of Mechanical Engineering
A method to calculate the load-deflection relation of the conical spring is proposed and verified by experimental data statically. The non-linearity of the spring rate and coil close effect by influencing the end effect are considered in the formulation. It shows that the maximum error between simulation and experimental results is 4 . 6%. The dynamic equations for the conical spring are also derived by considering the non-linear spring rate and damping effect due to coil clash. This is the first such modelling for a conical spring. The dynamic equations are solved by perturbation and the numerical methods. It is found that the natural frequency varies with the initial amplitude due to the coil clash in compression. Also, the maximum amplitude in compression is found to be smaller than the maximum amplitude in extension. (C) 1998 Academic Press Limited.
Modification on surface roughness by combining dry and wet etching
(2003)
Lee, CC
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Hsu, WY
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機械工程學系
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Department of Mechanical Engineering
The materials owning the rough surface have been adopted in many applications, such as MEMS devices, solar cell, DRAM, and so on. However, the modified targets on the previous methods were almost limited to silicon-type materials, and some had the limitations in the material properties. Recently, a process combining spin-on photoresist and one-step RIE was proposed to modify various materials, which can be etched by RIE. Here, a modification process, which combines spin-on photoresist, two-step RIE, and wet etching, is proposed to extend the feasible materials to be modified, because more materials can be etched by chemical solutions. Also, it is a low temperature process, and no extra mask is needed. From the experimental results, the modified surface can be used to alleviate stiction of microstructures, and a detachment length is found to be about 2.2 times longer than the cantilevers without the modified surface. Moreover, the related parameters for the anti-stiction are also developed, and the effects are compared with the previously developed one-step RIE method.
The enhancement on optical attenuation by a tunable non-smooth mirror
(2003)
Lin, CH
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Hsu, WY
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機械工程學系
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Department of Mechanical Engineering
Here the attenuation effect of a variable optical attenuator (VOA) with a tunable non-smooth mirror is investigated experimentally and analytically. The working principle of this VOA is based on the non-uniform deformation shape of a mirror membrane by thermally driven bimorph actuators. Before deformation, the surface roughness of Rymax and insertion loss of the mirror membrane are calibrated as 15 nm and 0.53 dB, respectively. The attenuation tests on smooth and non-smooth concave mirrors are also conducted. In. simulation, the attenuation effects by various smooth spherical shapes are modeled by ray tracing method and Gaussian beam theory, and the simulation results are compared with experimental data. It is found that the attenuation behaviors between simulation and calibration results on smooth, spherical concave mirrors have good agreement. Also, by comparing the experimental results from smooth and non-smooth concave mirrors, the attenuation is found to be enhanced by the non-smooth mirror surface evidently. The maximum dynamic range of attenuation is found to be more than 40 dB at input voltage of 46 V.
Variable optical attenuator with tunable nonsmooth curved mirror
(2004-11-01)
Lin, CH
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Wen, SY
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Hsu, WY
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機械工程學系
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Department of Mechanical Engineering
The attenuate effect of a variable optical attenuator (VOA) with a tunable nonsmooth curved mirror is fabricated and investigated experimentally and analytically. The working principle of this VOA is based on tuning the reflective mirror membrane into the nonsmooth curved mirror to enhance the optical attenuation, compared with that of the smooth curved mirror. The attenuation depending on the radius of curvature in a smooth concave mirror is simulated. Also, the attenuation tests on smooth and nonsmooth concave mirrors are conducted experimentally. The mirror membrane of the proposed VOA can provide not only the curved shape, but also a nonsmooth shape at the same time in the mirror membrane. By comparing the experimental results between the smooth and nonsmooth curved mirrors, the attenuation is shown to be enhanced at least 60% by the nonsmooth effect when the radius of curvature is smaller than 50 mm. The mirror membrane combining gold and low-stress nitride using back-side etching is sufficiently flat to provide an insertion loss of 0.53dB, and more than 40dB attenuation after deformation.