Browsing by Author "Hsu, WS"

Now showing 1 - 11 of 11

A two-way membrane-type micro-actuator with continuous deflections
(2000-09-01)
Hsu, CP
;
Hsu, WS
;
機械工程學系
;
Department of Mechanical Engineering
This paper presents design, simulation, fabrication, and testing of a novel two-way micro-membrane actuator able to deflect in both upward and downward directions with continuous deflections. The design concept, to realize two-way continuous movement, is achieved by arranging different bimorph structures at different regions of the actuator with two kinds of boundary conditions. The actuator comprises of a square membrane with four bimorph beams and one central bimorph plate on it. The material (e.g. aluminum) on the top layer of the bimorph beams and plate has a larger thermal expansion coefficient than the material (e.g. silicon dioxide) of the membrane. The driving voltages in the two operating modes are both less than 3.5 V at about 350 mW maximum power consumption for an 1 mm(2) membrane actuator. The upward and downward deflections achieved up to 50 and 15 mu m with maximum simulated temperatures less than 420 and 150 degrees C, respectively. A finite-element model is built to simulate the thermal mechanical behaviors that are compared with the experimental results. The design parameters influencing the deflections of the actuator are also discussed.
Improving the innovative capabilities of Taiwan's manufacturing industries with university-industry research partnerships
(2002)
Chang, PL
;
Hsu, WS
;
經營管理研究所
;
Institute of Business and Management
The experiences gained from Taiwan's university-industry collaborative program are presented by case studies. The framework of the university-industry partnership is presented. Both successful and failed case studies are detailed to extract the underlying understanding required to improve university-industry collaborative programs further. The capabilities of small and medium-sized enterprises, which are the majority of all enterprises in Taiwan, and the various ways of improving their innovative capabilities by effectively using university-industry partnerships, are also discussed. Supporting evidence which indicates that proper partnerships are the most effective means of improving the innovative capabilities of the manufacturing industries are also detailed.
Investigation of the four-bar linkage in a rear derailleur system with experimental verification
(1998)
Wu, PT
;
Hsu, WS
;
機械工程學系
;
Department of Mechanical Engineering
The derailleur system on a bicycle can be time-saving or labour-saving for riders by changing the suitable reduction ratio. In this study, a mathematical model of the four-bar linkage mechanism in a spatial rear derailleur is developed to simulate the cable force in shifting. The relation between the cable force and cable displacement is obtained and verified. It is found that friction between the cable and adjusting screw unit is a key factor. Then, the mathematical model is used to optimize the cable force. By changing the position of coupler point, we can reduce not only the maximum cable force by 9.26% but also the force difference between the maximum and minimum by 65.5%. Finally, a roller design to replace sliding contact between the cable and the adjusting screw unit is proposed to reduce the friction force.
Micro-fabrication of hemispherical poly-silicon shells standing on hemispherical cavities
(2001)
Lin, CH
;
Lo, YC
;
Hsu, WS
;
機械工程學系
;
Department of Mechanical Engineering
In the current paper, the fabrication process of a novel proposed hemispherical polysilicon shell standing on a hemispherical silicon cavity is demonstrated. This micro-fabrication process combines both bulk and surface micromachining, which include the isotropic wet etching, a novel mask design, the thick photo resist coating and exposure, and high-aspect-ratio curved sacrificial technique. In isotropic wet etching of a hemispherical cavity, the optimal concentration of etchant is experimentally determined along with adequate ultrasonic vibration during wet etching to produce the circle-like of hemispherical cavity. The conventional alignment mark, which will be destroyed during the rather long isotropic wet etching process, is replaced by a novel mask design with the second alignment mark. Also, for a deep hemispherical cavity larger than 100mum, the traditional photo resist can not be coated on the corner surface well. The thick photo resist, AZ4620, is found to be able to overcome this problem and be successfully exposed all through its bottom surface. Furthermore, the deposited sacrificial layer materials (PSG) on this cavity will usually result in thinner layer near the corner. In addition, the curved gap of PSG layer has the feature with high-aspect-ratio. These make the PSG etching difficult. Therefore, two steps etching process with two different hydrofluoric concentrations are used to release the PSG with 2mum thickness and 150mum arc length.
Nanocomposite effects on the coefficient of thermal expansion modification for high performance electro-thermal microactuator
(2005)
Tsai, LN
;
Cheng, YT
;
Hsu, WS
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
We employ a low-temperature stress-free electroplated nickel (EL) process with the addition of uniformly dispersed nanoparticles of diamond (< 500 nm) or SiO2 (< 80 nm) to investigate "nanocomposite effects" for the first time on the modification of the thermal expansion coefficient (CTE) and other mechanical properties of nickel and its correlation to power and reliability improvement of electro-thermal microactuators. Experimental results show that these material parameters can be either enhanced or deteriorated via the incorporation of different kind of nanopowders. Although the mechanical strength enhancement can be attributed to the intrinsic characteristics of the nanoparticle based on the rule of mixture, the discrepancy of CTE modification can only be explained with distinct composite microstructures which result in the performance improvement of the electro-thermal microactuator. This work has led to a possible research direction in the development of MEMS using the nanocomposites.
Ni-carbon nanotubes nanocomposite for robust microelectromechanical systems fabrication
(2006-01-01)
Tsai, LN
;
Cheng, YT
;
Hsu, WS
;
Fang, WL
;
電子工程學系及電子研究所
This article presents a novel fabrication process to enhance the operational performance and reliability of electrothermal microactuators. Carbon nanotubes (CNTs) (outer diameter: 10-20 nm, innerdiameter: 5-10 nm, length: 0.5-200 mu m) are incorporated in an electrolytic nickel deposition process in which a well-dispersed Ni-CNTs colloidal solution is made by a special acid oxidative method to synthesis a Ni-CNTs nanocomposite for device fabrication. Measurement results show that the microactuator plated with CNTs (0.028 g/L) needs the power requirement less 95% than the pure nickel device at the same output displacement of 3 mu m. The performance improvement of the electrothermal microactuator made of the nanocomposite, including device strength and power efficiency, has shown to be similar to the Ni-diamond composites (L. N. Tsai, G. R. Shen, Y. T. Cheng, and W. S. Hsu, The 54th Electronic Components and Technology Conference, June 2004, pp. 472-476)). In addition, the E/p ratio of the Ni-CNTs composite can be enhanced to 1.47 times higher than that of pure nickel, which is a fascinating result for resonant device fabrication. (c) 2006 American Vacuum Society.
Ni-P-CNTs nanocomposite film for MEMS applications
(2004)
Shen, GR
;
Tsai, LN
;
Chao, TY
;
Cheng, YT
;
Lin, TK
A Ni-P-CNTs (electroless phosphorus nickel-carbon nanotubes) nanocomposite film synthesis and related processes for MEMS device fabrication have been successfully developed and presented in this paper. With a special acid oxidative method, a well-dispersed nickel-CNTs colloidal solution has been produced without any aggregation, very suitable for microstructure fabrication. The nano-indentation measurement indicates that the Young's modulus and hardness of the Ni-P-CNTs nanocomposite film plated in the bath with 0.028g/L CNTs can greatly increase up to 666Pa and 29GPa, respectively, which is four times larger than that of pure nickel: The performance improvement of the electro-thermal microactuator made of the nanocomposite, including device strength and power efficient, have been proved similar to the Ni-diamond composites [1]. With the same power input, the device can provide 4 times elongation longer than that made of pure nickel. The mechanical strength of the actuator can also be enhanced to sustain the input power with two times larger than the pure one.
Parameters study to improve sidewall roughness in Advanced Silicon Etch process
(2001)
Liu, HC
;
Lin, YH
;
Chou, BCS
;
Hsu, YY
;
Hsu, WS
In ICP-RIE process, there have been many investigations on etching rate. However, only few published reports mentioned the sidewall roughness, which is a critical issue for optical devices. Here, experimental investigations about fabrication parameters in the STS Advanced Silicon Etch (ASE) process for sidewall roughness are performed. In our experiments, the photoresist of AZ1500 is used, and several parameters in the ASE process like over time, ramping time, Ar flow rate, platen power, and etching cycle time have been systematically studied. It is found that sidewall mean roughness can be down to 9.11 nm at etching rate of 2.5 mum/min. Comparing with other published works at similar sidewall roughness (around 10 nm), our experimental data have the highest etching rate. For the same STS ICP-RIE systems, our data have smallest sidewall roughness, comparing to previous literatures.
Structure design of a 2-D high-aspect-ratio resonant microbearn accelerometer
(2005-07-01)
Hwang, DH
;
Chin, KP
;
Lo, YC
;
Hsu, WS
;
機械工程學系
An accelerometer with concise structure having a resonant microbeam to measure 2-D acceleration is proposed. This structure is configured with a central proof mass suspended by four symmetrical and orthogonal high-aspect-ratio (HAR) microbeams. This dual-axis design is able to decouple a two-axis signal from a 2-D acceleration. An analytical model relating the linear relationship between the acceleration and the associated resonant frequency shift of microbeam is derived, and a finite element analysis (FEA) is also performed to confirm this model. The FEA result also shows that there is little cross talk between x and y directions of measurement, meaning that this structure is able to clecouple a planar 2-D acceleration into two independent acceleration components, and therefore the 1-D analytical model can be used to evaluate the 2-D acceleration on the x-y plane. In addition, the model is verified by testing results of one conventional dual-axis natural frequency shifted microaccelerometer (DFSM). The simulation result also shows that the sensitivity of the proposed HAR accelerometer is triple that of a conventional DFSM. (c) 2005 Society ofPhoto-Optical Instrumentation Engineers.
The design and fabrication of a movable O-shape micro-clamper
(2001)
Wu, CT
;
Hsu, WS
;
機械工程學系
;
Department of Mechanical Engineering
With the demanding of handling micro objects, the development of micro-clamper has emerged. Here an electro-thermally driven micro-clamper with adjustable vertical position is proposed. This micro-clamper is consisted of an adjusting unit and a clamping unit. The adjusting unit formed by four bimorph beams in the longitudinal direction can move the clamping unit vertically. The clamping unit formed by a pair of bimorph beams at the end of the adjusting unit is in the transversal direction. Due to the residual stress difference in the bimorph beam, at initial state, the adjusting unit in the longitudinal direction will bend upward, and the other two bimorph beams will also curl up to become a clamper. When the adjusting unit is heated, the whole device will move downwards. When the clamper unit is heated, two sides of the clamping unit will open up to a waiting state. It is hoped that the capability of adjusting the clamper in vertical position will provide larger operating range for the micro-clamper. The micro-clamper proposed here is batch-fabricated by surface micromachining. The testing results show that the adjusting unit can produce 8 mum downward displacement at input voltage of 2V and the clamping unit can be fully flattened around 5 V.
Thermally driven polysilicon actuators for lateral displacement
(1999-05-01)
Wu, MF
;
Lin, CH
;
Hsu, WS
;
機械工程學系
;
Department of Mechanical Engineering
A novel one-mask; polysilicon actuator driven by thermal expansion is developed, modeled and tested. The structures are heated by electric current due to resistive dissipation. Thermal strain is magnified by two mechanical mechanisms-lever and parallelogram. The device is tested in air and has a lateral 8 mu m-displacement by applying a low voltage (below 3.5 V). The critical current to reach melting point is about 67 mA with the input voltage less than 5 V. The simulation results by analytical and FEM schemes are compared with experimental data. The maximum output forces is measured with a built-in cantilever beam and is calculated to be about 3.3 mu N.