MEMS Pirani – Shrinking The Size Not The Quality

MEMS Pirani is just one of a number of ranges that that taken on micron-scale fabrication techniques. Micro-electro-mechanical Systems, shortened to MEMS for ease of use, are becoming increasingly popular in ultra high vacuum situations as they are smarter and smaller than their predecessors. As more sectors require this level of technology, understanding it becomes even more important.

Areas as diverse as consumer electronics, communications, surface analysis and biotechnology are calling out for MEMS technology. However, it is in areas that utilise ultra high vacuum technologies that the greatest use is being seen. Pressure, temperature and gas flow, amongst other properties, can all be measured using solid state MEMS devices. Pirani gauge have been at the forefront of vacuum measurement since their inception in 1906. However, older conventional Pirani gauges do present difficulties. The high temperature of the element presents an issue in process environments where the gases are thermally reactive. They also suffer from heat dissipation within the gauge. To operate at pressures in the region of 760 torr, conventional gauges need to be constructed with wire-to-wall distances that are great enough for heat transfer to happen by convective flow; however, this introduces mounting position sensitivity. All of these issues make achieving UHV environments difficult. Fortunately, these and a number of other issues are not present in MEMS Pirani gauge technologies. Additionally, the MEMS gauge has a faster response than conventional gauges, meaning that they can pump load locks at high vacuums that would overwhelm a conventional device.