**4. Conclusion**

In conclusion, we were able to demonstrate novel applications of the SMA MEMS actuator including both low power laser and low power and fast electrical joule heating. In other words, the SMA can be actuated by absorbing laser energy in the form of heat, or through pulsed electrical current. This was enabled by the development of deposition and characterizations of nanoscale thickness NiTi thin films. NiTi thin films with reversible changes in recovery stress were mated with other residual stressed thin films to enable reversible thermal actuation at MEMS scale. By incorporating nanoscale thin film SMA MEMS with good heat sinking design, we could achieve reversible actuations up to 3 kHz which is significantly greater than many previous reports for SMA actuators.
