| AVS 56th International Symposium & Exhibition | |
| Vacuum Technology | Monday Sessions |
| Session VT-MoA |
| Session: | Pressure, Partial Pressure, and Flow Measurement |
| Presenter: | J. Hendricks, National Institute of Standards and Technology |
| Authors: | J. Hendricks, National Institute of Standards and Technology T. Gooding, National Institute of Standards and Technology D.A. Olson, National Institute of Standards and Technology |
| Correspondent: | Click to Email |
In the mid 1990’s the development and use of micro electro mechanical systems (MEMS) enabled pressure sensor technology to make significant advances in both precision and accuracy. Resonant Silicon Gauges (RSGs) are MEMS sensors that are manufactured by micromachining silicon to produce silicon diaphragms nominally a few millimeters square by a fraction of a millimeter thick. Over the past decade, NIST has calibrated these gauges and has found them to be very stable, rugged, and ideally suited as core technology for a high-stability precision pressure standard that can be calibrated against the NIST primary pressure standards [1].
The RSGs use two single-crystal silicon resonators encapsulated in a vacuum microcavity. Changes in pressure on the diaphragm are determined by measuring strain-induced changes in the two resonant frequencies [2]. Since each resonant element is encapsulated in a vacuum, the most critical part of the sensor is never in direct contact with the calibration gas which makes the pressure sensor gas species independent. The RSG sensors are commercially available and NIST has performance data dating back over 9 years on one sensor that has been calibrated 18 times, and has a demonstrated average calibration shift of only 0.008% [3].
NIST has developed and built a Resonant Silicon Gauge Transfer Standard Package (RSG-TSP) with a range of 100 Pa to 130 kPa. NIST scientists recently completed a long-term stability study of this transfer standard, demonstrating that the uncertainty due to stability is only a few ppm at 130 kPa, increasing to 0.01 % at 100 Pa (k=1). This standard is expected to find applications in national “round robin” and international key comparisons of pressure standards, and is ideally suited for use as a “high end” precision pressure standard for secondary calibration laboratories.
[1] Hendricks, J.H. et.al. Metrologia 44 (2007) 171-176.
[2] Harada, K. et.al. 1999 Sensors and Actuators 73 261-266.
[3] NIST internal calibration report NC212.