US4947677A
Expired / Lapsed
US
⏱️ 0.0 years remaining
SAW determination of surface area of thin films
Assignee: United States Department of Energy
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Filing: 1988-10-05
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Granted: 1990-08-14
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Expires: 2008-10-05
Abstract
Abstract N 2 adsorption isotherms are measured from thin films on SAW devices. The isotherms may be used to determine the surface area and pore size distribution of thin films.
Inventors
- 👤 Gregory C. Frye
- 👤 Stephen J. Martin
- 👤 Antonio J. Ricco
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 20:14
CPC Classifications
G; G01; G01N; G01N15/00; G01N15/08; G01N15/088; G01N15/0893; G01N29/00; G01N29/02; G01N29/022; G01N2291/00; G01N2291/02; G01N2291/025; G01N2291/0256; G01N2291/04; G01N2291/042; G01N2291/0423; G01N2291/0426
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
102 words
A method of determining an adsorption isotherm of a thin film using a piezoelectric substrate having a surface, said method comprising the steps of: coating said thin film on said surface of said substrate; applying an adsorbate to said film; generating a surface acoustic wave along said coated surface, the acoustic wavelength of said surface acoustic wave being greater than the thickness of said film; measuring the change in frequency of said surface acoustic wave to determine the adsorption/desorption isotherm of said adsorbate on said film; and determining the mass/surface area of said film by applying the BET model to said isotherm.
Claim 2
Independent Claim
102 words
A method of determining an adsorption isotherm of a thin film using a piezoelectric substrate having a surface, said method comprising the steps of: coating said thin film on said surface of said substrate; applying an adsorbate to said film; generating a surface acoustic wave along said coated surface, the acoustic wavelength of said surface acoustic wave being greater than the thickness of said film; measuring the change in frequency of said surface acoustic wave to determine the adsorption/desorption isotherm of said adsorbate on said film; and determining the mass/surface area of said film by applying the BET model to said isotherm.
Claim 3
Dependent Claim
82 words
The method of claim 1 wherein the relationship between the frequency change and the mass/surface area of said adsorbate is defined as f/f.sub.o =-(k)c.sub.m f.sub.o m where f o is the frequency of the surface acoustic wave with no adsorbate applied to said substrate, k is the fraction of the wave path of said surface acoustic wave along said substrate covered by the film, c m is the mass sensitivity of said substrate, and m is the mass of adsorbed adsorbate/sensor area.
Claim 4
Dependent Claim
51 words
The method of claim 2 wherein said substrate has spaced transducers on said surface, said film being coated between said transducers, and said surface acoustic wave is generated by applying a RF electrical signal to one of said transducers at a frequency to generate a surface acoustic wave in said substrate.
Claim 5
Dependent Claim
14 words
The method of claim 3 wherein said adsorbate is nitrogen at its boiling temperature.
Claim 6
Dependent Claim
14 words
The method of claim 3 wherein said adsorbate is argon at its boiling temperature.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1993-08-13 | 1994-02-12 | 1994-08-14 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-08-13 | 1998-02-12 | 1998-08-14 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-08-13 | 2002-02-12 | 2002-08-14 | $7700.00 | Window Closed / Lapsed |