The high potential of shape memory alloys in developing miniature mechanical devices: a review on shape memory alloy mini-actuators

Shape memory alloys (SMAs) are a well-known class of smart materials. When subjected to certain thermal cycles, they are able to generate mechanical work by recovering a predetermined shape. Due to their high mechanical performances, their compactness and lightness, SMAs can be easily included in mechanical devices of small dimensions and used as actuating elements. There are rather few companies worldwide that deal in SMA mini-actuators; we can find, nonetheless, quite a large number of studies about them. In this paper, we illustrate the state of art of SMA mini-actuators, in the meaning of mini-modular-mechanical devices activated by SMA materials; particular attention is granted to the commercial SMA mini-actuators and to the most recent and relevant publications and patents in this field. Ferromagnetic shape memory alloys are presented as well.