In the field of microsystems, there is strong interest in reducing the size of devices. However, the assembly of different components becomes more and more difficult as miniaturisation progresses. To solve this problem, we have developed a new concept of monolithic micro-devices. In this concept, one piece of Shape Memory Alloy (SMA) is considered as a complete mechanical system including all functionalities of the device. For example, in a microgripper, bias spring, jaws and actuator will be integrated within the same piece of material.Without special thermo-mechanical treatments, the shape memory effect is not reversible. In conventional devices made up of separate elements, a bias spring is typically required. In the monolithic design, a part of the SMA has to fulfil this function. This implies that different parts of the material will have different mechanical properties and that shape memory effect is only introduced in some predefined areas.In this paper, a new approach based on local laser annealing is proposed. The laser is used to locally crystallise the SMA. Annealed parts will show shape memory and the non-annealed ones will have elastic behaviour. This method can be applied on work-hardened material as well as on amorphous thin film. With this tool, complex mechanical devices with active and passive parts can be designed.In the first part, we present the new technology of laser annealing of SMA and its effects on the material properties. In the second part, some applications of this technology are introduced.
Bellouard, Y. J., Lehnert, T., Clavel, R., & Gotthardt, R. (2001). Laser Annealing of Shape Memory Alloys: A Versatile Tool for Developing Smart Micro-devices. Journal de Physique IV, Colloque, 11, 571-576. https://doi.org/10.1051/jp4:2001895