Gas detector with low-cost micromachined field ionization tips

This letter describes a low-cost fabrication of field ionization tips for gas detection application. The method addresses some of the most important aspects of micro gas detector technology; namely, manufacturing cost, sensitivity and reproducibility. The tips were designed and fabricated with standard microfabrication technologies: thermal oxidation, wet chemical etching and sputtering. However, the major achievement is the use of a low-resolution mask to position the tips very closely to a second electrode in a self-aligned process. In our investigation, the vaporized CH/sub 3/COOH was selected as the sample gas to measure the detector sensitivity. The minimum-measured sensitivity of the detector is 14 ppm and this was accomplished at an operating voltage of only 5 V.