A Fast, Large-Stroke Electrothermal MEMS Mirror Based on Cu/W Bimorph

Abstract

This paper reports a large-range electrothermal bimorph microelectromechanical systems (MEMS) mirror with fast thermal response. The actuator of the MEMS mirror is made of three segments of Cu/W bimorphs for lateral shift cancelation and two segments of multimorph beams for obtaining large vertical displacement from the angular motion of the bimorphs. The W layer is also used as the embedded heater. The silicon underneath the entire actuator is completely removed using a unique backside deep-reactive-ion-etching DRIE release process, leading to improved thermal response speed and front-side mirror surface protection. This MEMS mirror can perform both piston and tip-tilt motion. The mirror generates large pure vertical displacement up to 320 µm at only 3 V with a power consumption of 56 mW for each actuator. The maximum optical scan angle achieved is˘18˝at 3 V. The measured thermal response time is 15.4 ms and the mechanical resonances of piston and tip-tilt modes are 550 Hz and 832 Hz, respectively.

Modeling and Control of a Large-Stroke Electrothermal MEMS Mirror for Fourier Transform Microspectrometers

“…To accomplish this, the photodiode-based tilting angle detector [23] and resonant inductive coupling position sensor [24] are two possible solutions. Further, considering that this LSF bimorph-based MEMS mirrors have large thermal response time (∼100 ms) which will limit the scan speed, our future work will focus on design, fabrication and control of a large-stroke electrothermal micromirror with faster thermal response [25].…”

Decay time control of mass diffusion in a transient grating using a fringe-tunable electrothermal Fresnel mirror

“…Heat conduction through the mirror was not significant; therefore, the thermal cross-talk between the two actuators was negligibly small. The total thermal resistance of the actuator was roughly estimated to be around 6×10 4 K/W which is higher than bimetal electrothermal actuators (Zhang et al, 2015) because of low thermal diffusivity of SU-8 (0.14 mm 2 /s). …”

Design and Fabrication of a Kirigami-Inspired Electrothermal MEMS Scanner with Large Displacement

“…Compared with electrostatic, piezoelectrical, and electromagnetic actuations, an electrothermal MEMS scanner can achieve large displacement (several hundred micrometers) without resonant operation. To date, various novel designs for electrothermal MEMS scanners with vertical out-of-plane actuation have been proposed [3][4][5][6]8,[14][15][16]. For example, Zhang et al [14] presented a lateral shift-free actuator design using three bimorph hinges and two multimorph segments to compensate for the lateral shift.…”