Nitinol thin foil irradiated by continuous mode laser diode for wireless chromatic micro-actuation

In this article a method for wireless micro-actuation based on shape memory alloy (SMA) is investigated. First of all, a numerical model is presented having conduction and convection heat transfer modules and the effect of phase transformation is taken into account during heating and cooling of SMA. The numerical simulation is performed using Cast3M code and the physical properties of Nitinol (which is an alloy of nickel and titanium) irradiated by a continuous mode laser diode of wavelength 785 nm and optical power equal to 102 mW. An experimental work is carried out to validate the numerical modelling. For this purpose a square sample of Nitinol (2 mm times 2 mm times 100 mum thick) is irradiated with the laser source and the temperature rise within the sample is measured using miniature thermocouples. A good agreement is found between the experimental and numerical results. At the end, the chromatic response of Nitinol thin foils using Bragg reflector structure is presented.