NiTi shape memory alloy thin film micro-cantilevers array

An un-cooled far infrared (IR) imaging sensor micro-array was fabricated using Ni-rich NiTi shape memory alloy (SMAs) films. NiTi SMA films of similar to 5 mu m thick were deposited on glass substrates by the direct current (DC) magnetron sputter deposition method. Micro-cantilever arrays were then patterned by the photolithographic technique. After crystallization aging treatments and thermo-mechanical training, the SMA films exhibit typical R-phase transition near room temperature. The thermo-mechanical sensitivity of the SMA film was found higher than that of bi-material films after the two way shape memory (TWSM) training. Illumination of the micro-arrays using IR light source had increased the temperature locally and caused curving up of the illuminated micro-cantilevers. This subsequently had led to a decrease in local reflectivity, which made digital IR imaging feasible. (C) 2011 Elsevier B.V. All rights reserved.