Wen-Chih Chen

A novel single-layer bi-directional out-of-plane electrothermal microactuator

In this study, a novel bi-directional out-of-plane electrothermal actuator is designed and fabricated. Unlike the bi-metal and hot-cold arm thermal actuator, this actuator can move in two directions. Since the actuator consists of only a single layer thin film material, it can prevent delamination. According to the static load-deflection test, this actuator can achieve bi-directional actuation with amplitude near several microns when driven at 5 V. According to the vibration test, the dynamics of the actuator are influenced not only by the thermal characteristics but also by the vibration modes. Consequently, the thermal actuator still has a significant output when driven near 40 kHz. The actuator was subjected to a fatigue test which shows that its resonant frequency remains unchanged after 10/sup 9/ cycles of continuous operation with driving voltage at 2.25 V/sub pp/.

Design and implementation of a novel “polymer joint” for thermal actuator current and thermal isolation

This study presents a novel thermal isolation component “polymer joint” to reduce the current and heat flow (by conduction) between micro thermal actuators. An optical stage consisted of V-beam thermal actuators for optical-tracking and thermal-driven focal-length tunable micro polymer lens for optical-focusing is employed to demonstrate the present concept. To overcome the thermal coupling of these two actuators by heat-conduction, the two components fabricated by SOI wafer (Si∼150W/m-k) are connected by the low thermal conductivity joints (polymer∼0.2W/m-k). The displacement provides by the V-beam actuator is about ±13µm. The temperature difference is about 80°C measurement by infrascope. The variation of micro lens radius of curvature is about 1%.

Removable fast package technology for MEMS devices using polymer connectors and silicon sockets

This paper describes a novel removable and reusable packaging technique that can act as temporary protection for suspended microelectromechanical system (MEMS) devices during dicing and handling. The technique uses a polymer cover with built-in flexible connectors and is prepared using a molding process, and then mechanically interlocked to the MEMS device with built-in socket arrays. The shapes of the polymer connector and the silicon sockets are easily patterned and tuned using microfabrication processes. The press-fit design of the connectors and the sockets, and the hydrophobic characteristic of the polymers provide waterproofing protection. We have demonstrated that the interlocking of modified SCREAM devices with the PDMS polymer cover was demonstrated at a typical interlocking strength of approximately 1 MPa.

An in-plane dispersive system utilizing micro tunable vertical grating

A miniaturized tunable dispersive optical system is presented, which consisted of a novel tunable vertical grating operated in the visible. Preliminary results for fabricating and testing such device are also conducted to prove the feasibility

A novel solid state tunable micro lens

This study reports the current progress of the novel thermal-actuated tunable focal-length micro polymer (PDMS) lens. The prototype of solid state only tunable lens demonstrates a typical variation of focal length from 1852 mum to 1083 mum under a 60 mA driving current. Moreover, this study also demonstrates the capability to integrate the tunable polymer lens with other optical components such as the conventional and dual-focus Fresnel lens. The resulted compound (PDMS+Fresnel) lens reduced the focal-length of Fresnel lens from 13500 mum to 5038 mum. Moreover the focal-length of compound lens was further dropped to 3523 mum at 60 mA driving current. A dual-focus compound lens was also realized to reduce its focal-length from 8000 mum/4000 mum to 1343 mum/975 mum. The compound lens has potential to further perform beam shaping and remove aberrations.

Toward the micromachined vibrating gyroscope using (111) silicon wafer process

The issues regarding structure design and fabrication in improving the performance of MVGs are discussed. Although using (111) Si wafer with existing HARM process is appropriate, some limitations on design and fabrication still exist. This study proposes a novel BELST process that can improve the device performance as well as fabrication capability of the existing techniques. The salient features of the process are described, and various design concepts have been demonstrated from the fabrication results. According to the result, MVGs with desired shape and thickness can easily be obtained using the developed BELST process.

Novel Micro Lens with Tunable Astigmatism

A novel astigmatism-tunable micro lens is reported in this paper. The device is based on a thermal-actuated tunable lens. Asymmetric boundary condition is further introduced on silicon conducting ring of lens to invoke asymmetric deformation of polymer lens as well as astigmatic change of PDMS-lens. The astigmatism is easily controlled via driving current. This study demonstrates the astigmatism variation by aspect ratio of anterior focus-spot, which changes from 9.34 to 1.12 while driving current increases from 0 mA to 70 mA. This astigmatism tuning approach paves the ways of MEMS-based aberration corrector and laser focus-spot shaper.

Removable fast packing of MEMS devices using polymer connectors and silicon sockets

This study reports a novel packaging technique using the polymer cover. The polymer cover with built-in flexible connectors is mechanically interlocked to Si-substrate with built-in socket arrays. These components are realized using microfabrication processes and further integrated with MEMS-device chip. The shapes of socket/connector are easily patterned using processes. The typical interlocking strength was ranging 1 MPa. Moreover, the hydrophobic characteristic of polymers provides the waterproof condition. In applications, the interlocking of SCREAM devices and polymer cover was demonstrated. This removable/reusable packaging technique can act as a temporary protection for suspended MEMS devices during dicing and handling.