Applications of Laser Processing for Sensors and Actuators

Abstract

ABSTRACTThe fabrication of sensors and actuators requires new materials with multicomponent stoichiometry as well as new three-dimensional microstructures. We present several potential applications of laser processing for the fabrication of sensors and actuators. The first example concerns gas sensors which require ionic conductor multicomponent ceramics whose stoichiometry is not maintained by conventional sputtering methods. We have successfully employed pulsed laser deposition (PLD) for producing high quality NASICON (Na SuperIonic CONductor) thin films. XPS measurements show that all elements are transferred from a target of Na1+xZr2SixP3-xO12, (where 0 < x < 3 ) to the substrate, and that the composition of the thin film is very close to that of the target. Electrical measurements show good ionic conductivity. Thus, these films are suitable for the fabrication of electrochemical gas sensors. Since such ceramic thin films are very sensitive to liquids, wet etching is prohibited, and patterning is done using laser ablation. For other applications, a laser micromachining technique has been developed to make tunnels and cavities in Si under SiO2 films, based on the laser-induced CI2 etching of Si and high chlorine Si/SiO2 etch rate ratios. Tunnels with length of up to 3 mm and cavities of 100×100 cm2 were successfully fabricated in SiO2/Si bilayer samples. These are usable in microfluidic or gas pressure measurement systems.