US4066567A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Liquid crystal cumulative dosimeter
Assignee: Temple University
•
Filing: 1976-02-04
•
Granted: 1978-01-03
•
Expires: 1996-02-04
Abstract
Abstract Cumulative temperature dosimeter utilizes a temperature dependent reaction in a cholesteric liquid crystal composition to produce a color change indicative of temperature exposure over a period of time. Typically, the composition includes, as a solvent, a cholesteric liquid crystal, such as a mixture of p-methoxy-p'-n-butyl-azoxybenzene, cholesteryl nonanoate, cholestyl chloride, and cholesteryl oleyl carbonate. One or more solutes are included, the solutes being reactive at a rate which is temperature dependent, to cause either generation or consumption of mesogenic compounds. In turn, the pitch of the solvent, observable as a visible color change, is affected in proportion to the cumulative temperature exposure of the composition.
Inventors
- 👤 Mortimer M. Labes
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 22:17
CPC Classifications
G; G01; G01K; G01K11/00; G01K11/12; G01K11/16; G01K11/165; C; C09; C09K; C09K19/00; C09K19/04; C09K19/42; C09K19/50; G01K3/00; G01K3/02; G01K3/04; Y; Y10; Y10S; Y10S252/00; Y10S252/962
Claims Analysis
Total Claims: 20
Claim 1
Independent Claim
94 words
A cholesteric liquid crystal composition comprising a cholesteric liquid crystal solvent and reactive solutes adapted to enter into a chemical reaction, said liquid crystal solvent having a wavelength of maximum reflection the temperature dependence of which is negligible at the temperatures involved in the reaction, the rate of said reaction being temperature dependent, the products of said reaction being adapted to cause a characteristic change in the light reflecting properties of said composition, the degree of said change being cumulatively indicative of the exposure of said composition to temperature outside of a preselected limit.
Claim 2
Dependent Claim
94 words
A cholesteric liquid crystal composition comprising a cholesteric liquid crystal solvent and reactive solutes adapted to enter into a chemical reaction, said liquid crystal solvent having a wavelength of maximum reflection the temperature dependence of which is negligible at the temperatures involved in the reaction, the rate of said reaction being temperature dependent, the products of said reaction being adapted to cause a characteristic change in the light reflecting properties of said composition, the degree of said change being cumulatively indicative of the exposure of said composition to temperature outside of a preselected limit.
Claim 3
Dependent Claim
22 words
A composition, as recited in claim 1, wherein said different light reflecting properties are observable as a color change in said composition.
Claim 4
Dependent Claim
23 words
A composition, as recited in claim 1, wherein said solutes are reactive at a temperature dependent rate to generate or consume mesogenic molecules.
Claim 5
Dependent Claim
29 words
A composition, as recited in claim 3, wherein said cholesteric liquid crystal solvent comprises a mixture of cholesteryl nonanoate, cholesteryl chloride, cholesteryl oleyl carbonate, and the isomers of para-methoxy-p'-n-butylazoxybenzene.
Claim 6
Dependent Claim
48 words
A composition, as recited in claim 4, wherein said mixture consists of 0.9 parts by weight of cholesteryl nonanoate, 1.1 parts by weight of cholesteryl chloride, and 2 parts by weight of cholesteryl oleyl carbonate, combined with 40% by weight of a sub-mixture of the isomers of paramethoxy-p'-n-butylazoxybenzene.
Claim 7
Dependent Claim
48 words
A composition as recited in claim 4, wherein said mixture consists of 0.9 parts by weight of cholesteryl nonanoate, 1.1 parts by weight of cholesteryl chloride, and 2 parts by weight of cholesteryl oleyl carbonate, combined with 55% by weight of a sub-mixture of the isomers of paramethoxy-p'-n-butylazoxybenzene.
Claim 8
Dependent Claim
71 words
A composition, as recited in claim 1 wherein said composition comprises a mixture of left-handed cholesteric compounds selected from the group consisting of cholesteryl nonanoate, cholesteryl hexanoate, cholesteryl decanoate or any other straight chain cholesteryl C 1 to C 20 alkanoate and right-handed cholesteric compounds selected from the group consisting of cholesteryl chloride, cholesteryl bromide, cholesteryl iodide and cholesteryl nitrate, in combination with any low temperature mesomorphic carbonate ester of cholesterol.
Claim 9
Dependent Claim
24 words
A composition, as recited in claim 7, wherein said low temperature mesomorphic carbonate ester of cholesterol is cholesteryl oleyl carbonate or cholesteryl-2-(ethoxyethoxy) ethyl carbonate.
Claim 10
Dependent Claim
30 words
A composition, as recited in claim 3, wherein said reactive solutes enter into a mesogenic reaction selected the group consisting of aldehyde-amine condensations, Schiff base-amine reactions or benzoate ester formations.
Claim 11
Dependent Claim
18 words
A composition, as recited in claim 9, wherein said reactive solutes are p-ethoxybenzaldehyde and (+) or (-) α-phenethylamine.
Claim 12
Dependent Claim
13 words
A composition, as recited in claim 9, wherein said reactive solutes are ##STR6##
Claim 13
Dependent Claim
15 words
A composition, as recited in Claim 9, wherein said reactive solutes are N-(p-methoxybenzylidene)-p-n-butyl-aniline and (-)-α-phenethylamine.
Claim 14
Dependent Claim
13 words
A composition, as recited in claim 9, wherein said reactive solutes are ##STR7##
Claim 15
Dependent Claim
28 words
A composition, as recited in claim 3, wherein said reaction rate is dependent on and proportional to exposure of said composition to a temperature above some predetermined maximum.
Claim 16
Dependent Claim
29 words
A container, having at least one transparent section to permit observation of the color of a material disposed therein, said container containing a composition as recited in claim 1.
Claim 17
Dependent Claim
29 words
A container with composition therein, as recited in claim 15, said container having a shape adapted to extend inwardly into a product to sense the cumulative temperature exposure thereof.
Claim 18
Dependent Claim
29 words
A container with composition therein, as recited in claim 15, wherein said container includes a color indicator for comparison to said composition to determine the cumulative dosage sensed thereby.
Claim 19
Independent Claim
104 words
A method of determining the cumulative time of exposure of an indicator element to temperatures above a preselected limit said method comprising (1) providing a cholesteric liquid crystal composition comprising a cholesteric liquid crystal solvent and reactive solutes adapted to enter into a chemical reaction at temperatures above said preselected temperature limit, said liquid crystal solvent having a wavelength of maximum reflection the temperature dependence of which is negligible at the temperatures involved in the reaction, the rate of said reaction being temperature dependent, and (2) after a period of time, observing any change in the optical properties of the cholesteric liquid crystal composition.
Claim 20
Independent Claim
104 words
A method of determining the cumulative time of exposure of an indicator element to temperatures above a preselected limit said method comprising (1) providing a cholesteric liquid crystal composition comprising a cholesteric liquid crystal solvent and reactive solutes adapted to enter into a chemical reaction at temperatures above said preselected temperature limit, said liquid crystal solvent having a wavelength of maximum reflection the temperature dependence of which is negligible at the temperatures involved in the reaction, the rate of said reaction being temperature dependent, and (2) after a period of time, observing any change in the optical properties of the cholesteric liquid crystal composition.
References Cited (Backward Citations)
GB224674A
Cited
US2951764A
Cited
US3409404A
Cited
US3576761A
Cited
US3594126A
Cited
US3773747A
Cited
US3697297A
Cited
US3679290A
Cited
US3720623A
Cited
US3768976A
Cited
US3970579A
Cited
US3853785A
Cited
JPS4869775A
Cited
US3819531A
Cited
US3872140A
Cited
US3974317A
Cited
US3877411A
Cited
US3966414A
Cited
US3927977A
Cited
US4011046A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1981-01-02 | 1981-07-04 | 1982-01-03 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1985-01-02 | 1985-07-04 | 1986-01-03 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1989-01-02 | 1989-07-04 | 1990-01-03 | $7700.00 | Window Closed / Lapsed |