title: Potential Stable Low-Permeation Rate Standard Based on Micro-machined Silicon.
abstract: Silicon wafers with micro-machined holes were evaluated for use as low-permeation-rate standard artifacts. Accuracy, stability, and reliability were assessed. Two independent experimental techniques for evaluating permeation were used: chilled mirror hygrometer and mass loss. The wafers exhibited a well-defined linear relationship between hole area and resultant water partial pressure for both techniques, although the mass loss curve exhibited a constant vertical offset from the hygrometer curve, attributed to water loss through the O-ring seal. In contrast to polymer permeation standards, Si wafers provided long-term reproducible permeation rates. However, they were also highly fragile, with most of them cracking during the course of the investigation.
authors.affiliation: Focused Labs, LLC, Denver, CO 80239.
authors.forename: Adrian
authors.initials: A
authors.lastname: Verwolf
authors.affiliation: National Institute of Standards and Technology, Boulder, CO 80305.
authors.forename: Chris
authors.initials: C
authors.lastname: Poling
authors.affiliation: National Institute of Standards and Technology, Boulder, CO 80305.
authors.forename: Nick
authors.initials: N
authors.lastname: Barbosa
authors.affiliation: National Institute of Standards and Technology, Boulder, CO 80305.
authors.forename: Grady
authors.initials: G
authors.lastname: White
authors.affiliation: National Institute of Standards and Technology, Boulder, CO 80305.
authors.forename: Nikki
authors.initials: N
authors.lastname: Rentz
keywords: Si; calibration; chilled mirror hygrometer; mass loss; permeation; standard