Environmental indicator device and method
US4646066A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jun 27, 1985 |
| Grant date | Feb 24, 1987 |
| Priority date | — |
| Expiry date | Jun 27, 2005 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01N27/122
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A device for monitoring environmental exposure includes an element whose electrical properties change, in a predetermined way, in response to the environmental exposure. The element may be part of a tuned circuit or of a shield for a tuned circuit. In either case, when the tuned circuit is interrogated, preferably by an r.f. or microwave signal, it emits a signal whose intensity depends on the electrical properties of the element. Thus, an incremental environmental exposure can be measured by a change in the signal intensity. The device is particularly useful for monitoring the condition of perishable materials, because it can be located with the perishable inside a packaging material during both storage and interrogation.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.