US3831435A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Silver-foil psychrometer for measuring leaf water potential
Assignee: United States Department of Agriculture
•
Filing: 1973-04-06
•
Granted: 1974-08-27
•
Expires: 1993-04-06
Abstract
Abstract An miniature apparatus for measuring the water potential of leaves in situ without temperature control. The apparatus includes a metal disk with a central cavity, a pair of thermally conductive washers mounted on the bottom of the disk, a reference thermocouple connected to each washer, and a measuring thermocouple located in the cavity. The thermocouples are connected in series.
Inventors
- 👤 G Hoffman
- 👤 S Rawlins
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 14:56
CPC Classifications
G; G01; G01N; G01N25/00; G01N25/56; G01N25/62; G01N25/64
Claims Analysis
Total Claims: 3
Claim 1
Independent Claim
167 words
A miniaturized device for measuring the water potential of a leaf in situ on a living plant while the leaf remains at ambient temperature, comprising a. a disk of metal foil having a diameter smaller than the width of the leaf whose water potential is to be measured, said disk having a flat annular portion and a central cup-like cavity, said cavity forming a closed equilibrium chamber in conjunction with the leaf when the device is in operative position sealed to the surface of the leaf, b. a measuring thermocouple junction mounted within said cavity, c. a pair of half-washers of metal foil mounted on the bottom of said disk and extending around the flat portion thereof, being cemented in place with a thin film of a thermally conductive but electrically insulating adhesive material, d. a pair of reference thermocouple junctions, each being soldered to one of said half-washers, e. and means for electrically connecting said three thermocouples in series, whereby to provide a Peltier-type thermocouple system.
Claim 2
Dependent Claim
167 words
A miniaturized device for measuring the water potential of a leaf in situ on a living plant while the leaf remains at ambient temperature, comprising a. a disk of metal foil having a diameter smaller than the width of the leaf whose water potential is to be measured, said disk having a flat annular portion and a central cup-like cavity, said cavity forming a closed equilibrium chamber in conjunction with the leaf when the device is in operative position sealed to the surface of the leaf, b. a measuring thermocouple junction mounted within said cavity, c. a pair of half-washers of metal foil mounted on the bottom of said disk and extending around the flat portion thereof, being cemented in place with a thin film of a thermally conductive but electrically insulating adhesive material, d. a pair of reference thermocouple junctions, each being soldered to one of said half-washers, e. and means for electrically connecting said three thermocouples in series, whereby to provide a Peltier-type thermocouple system.
Claim 3
Dependent Claim
21 words
The device of claim 1 wherein the said disk and half-washers are made of silver foil about 50 microns in thickness.
References Cited (Backward Citations)
US3739629A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-08-26 | 1978-02-25 | 1978-08-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-08-26 | 1982-02-25 | 1982-08-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-08-26 | 1986-02-25 | 1986-08-27 | $7700.00 | Window Closed / Lapsed |