Wavelength-Selective Shape Memory Alloy for Wireless Microactuation of a Bistable Curved Beam

Contactless and selective energy transfer to a bistable micro-actuator using laser heated shape memory alloy

“…To actuate the curved beam from one stable position to the other, the force generated by the laser heated SMA active element must be greater than the force required to actuate the curved beam. The detailed procedure to measure the force generated by the laser heated SMA active element was explained in [23]. The measured generated force values with respect to the optical powers have been tabulated in the first two rows of table 1.…”

“…In our previous work [23,39], the feasibility of selective addressing using two different wavelengths, 660 nm and 785 nm, was proved. In that work, a Bragg structure made of alternate layers of amorphous hydrogenated silicon (a-Si:H) and amorphous polymethacrylic acid (a-pMA) was deposited onto the SMA active elements of thickness 100 µm.…”

“…The contactless and selective energy transfer method to actuate a bistable micro-actuator using laser heated SMA active elements has already been demonstrated [23]. In the presented work, the detailed theoretical possibility and the experimental evidence to actuate different stroke lengths of the bistable actuator with different laser power values are presented.…”

“…Different phenomena have been utilized to trigger the laser driven actuators, such as thermal expansion [17], thermally induced bilateral deflection [18], laser induced electrostatic interactions [19], piezoelectric effect [20], light induced force [21], solid-solid phase transformation (shape memory alloy) [22] etc. Amongst all thermally active elements, SMAs can be considered as the best candidate due to the high power to weight ratio, small size, silent actuation, and compliance with harsh environment [23]. A temperature change in these alloys (SMAs) causes a solid-solid phase transformation within the crystalline structure of the material.…”

“…The fabrication process of the curved beam, the SMA active element and the deposition of optical filters directly onto the SMA active element is described in detail. Instead of two wavelengths (as in the previous case [23]), the system will be made selective for four wavelengths (532 nm, 660 nm, 785 nm, and 980 nm) thanks to silver-polymer-silver structure used for the optical filters. A detailed experimental analysis of the proposed selective energy transfer method is presented and the effect of this selective addressing onto the dynamics of the system is discussed.…”