A Liquid Crystal Based Gas Sensor Using Microfabricated Pillar Arrays as a Support Structure

We present principles for the design of a vapor-phase chemical sensor based on orientational transitions of nematic liquid crystals (LC) supported by a microfabricated pillar array structure. These principles are demonstrated by using the structure to detect vapor-phase Di-methyl methyl phosphonate (DMMP) via change in the intensity of light transmitted through the LC (5CB: 4-pentyl-4-cyanobiphenyl). The micro-pillar support structure stabilizes a thin (-22 mum) LC film by capillary force. The structure offers easier filling of LC, reduced susceptibility to gravity and shock, and is capable of embedding different thicknesses of LC films. Concentrations down to 10 ppm of DMMP were detected.