Cholesteric liquid crystal formulations and time/temperature monitoring means
AssigneeBiosynergy, Inc.
InventorsFred K. Suzuki, Sharon M. Mead, Noble H. Yoshida, Robert H. Dobberstein
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Abstract
Described are cholesteric liquid crystal formulations suitable for use as indicators of time and/or temperature, and methods for reliably characterizing and reproducing initial and subsequent batches of such cholesteric liquid crystal formulations. The formulations have a time-dependent, temperature-dependent limit in a pseudo-irreversible liquid crystal phase wherein when said limit is exceeded, the formulations exhibit a color change which is irreversible by cooling.
Claims34
Time/temperature-monitoring means comprising a choloesteric liquid crystal material having an irreversible phase wherein said material quenched from a first temperature at or above its color-play temperature range to a second temperature below its color-play temperature range while retaining a color characteristic of said material at said material at said first temperature, wherein said material has a pseudo-irreversible liquid crystal phase at a temperature below said color-play temperature range and at a temperature above said irreversible phase, said pseudo-irreversible phase being the only phase located between said color-play temperature range and said irreversible phase, said material having a defined time-dependent temperature-dependent limit said pseudo-irreversible liquid crystal phase, wherein when said limit is exceeded, said material exhibits a color change which is irreversible by cooling.
Dependencies are inferred from the claim text.