In view of the specific advantages of using vacuum as device medium and field emission cathode as electron source, a renewed interest in vacuum microelectronics utilizing advanced IC technology is emerging. This thesis demonstrates an application of field emission emitters in two novel pressure sensors. One is based on a diode structure with one electrode fabricated on a pressure sensitive thin diaphragm. The other has two tip-to-tip cantilever beam emitters with a small gap between tips. Both cone-shape and wedge-shape emitters are studied. Some new results on the analysis of the two generic emitter array diodes regarding the geometric design parameters, which are essential to device design, are presented. Various wet and dry etching techniques of forming emitter arrays are compared. A combined wet/dry fabrication process is developed to achieve array uniformity and reproducibility. The characteristics of pressure sensor with ideal field emission array are simulated, methods to take into consideration the nonuniformity of array tips, an inevitable result from fabrication practice, is also discussed. A study of field emission from silicon-based emitter array is present and various factors to affect the stability of emission are investigated. The performance of two fabricated experimental pressure sensors are evaluated, one with cone-shape emitter array and the other with cantilever beam field emitters.