Optically driven shape memory alloy microactuators

George K. Knopf

doi:10.1117/12.517460

4 March 2004 Optically driven shape memory alloy microactuators

George K. Knopf

Proceedings Volume 5263, Intelligent Manufacturing; (2004) https://doi.org/10.1117/12.517460
Event: Photonics Technologies for Robotics, Automation, and Manufacturing, 2003, Providence, RI, United States

Abstract

Indirect optical methods of mechanical actuation exploit the ability of high intensity light sources to generate heat, and thereby influence the thermal properties of gases, fluids or solids. Optical actuators that utilize this photo-thermal effect for creating structural displacement often produce very large power/weight ratios. This paper describes the basic concept and operation of two optically driven micro-mechanisms that use the shape memory effect of 50/50 nickeltitanium (NiTi) material to generate the desired force and displacement. Shape memory alloys (SMA) such as NiTi exhibit reproducible phase transformation effects when undergoing repetitive heating and cooling cycles. Increasing the temperature above the ambient conditions of a pre-loaded NiTi wire or foil will cause the material element to undergo a martensite-to-austenite phase transformation and move the position of an attached load a distance of approximately 4% of the overall length. The reduction in the length can be recovered by cooling the SMA material back to the original temperature. The number of times the NiTi material can exhibit this shape memory effect is dependent upon the amount of strain, and consequently, the total distance through which the actuating material is displaced. The proposed devices use a focused high-intensity light source to provide both the energy and control signal needed to activate a simple wire shaped SMA element in a microcantilever beam and a SMA thin film in a diaphragm micropump.

Citation Download Citation

George K. Knopf "Optically driven shape memory alloy microactuators", Proc. SPIE 5263, Intelligent Manufacturing, (4 March 2004); https://doi.org/10.1117/12.517460

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