Method and apparatus for determining average environmental conditions

• US 20040008112A1
• Filed: 07/09/2002
• Published: 01/15/2004
• Est. Priority Date: 07/09/2002
• Status: Active Grant

• Current Assignee: Battelle Memorial Institute
• Original Assignee: Battelle Memorial Institute
• Inventors: Carrender, Curt
• Granted Patent: US 6,927,687 B2
• Time in Patent Office: Days
• US Class Current: 340/539.26
• CPC Class Codes: G05D 23/24 the sensing element having a resistance varying with temperature, e.g. a thermistor
• CPC Class Codes: G06K 19/0717 the sensor being capable of sensing environmental conditions such as temperature history or pressure

Abstract

A system for monitoring an environmental condition and determining the average environmental condition using an RFID tag and reader, the tag configured to have at least one module with known characteristics that are dependent on the environmental condition and to be responsive to interrogation by the reader to asses the state of the known characteristics for determining the average environmental condition.

Claims

1. A device for measuring environmental conditions, comprising:

a first module having known characteristics dependent on at least one environmental condition;

a second module having known characteristics dependent on time;

the first and second modules configured to be responsive to radio frequency interrogation of the state of their respective known characteristics for assessing the average of the at least one environmental condition.

2. The device of claim 1 wherein the at least one environmental condition comprises temperature.

3. A method for detecting an environmental condition during an unpowered state of an RFID tag, the method comprising:

providing an RFID tag having a first module with known characteristics dependent on the environmental condition;

interrogating the RFID tag to assess the state of the known characteristics; and

determining the average of the environmental condition in response to the state of the known characteristics of the first module.

4. The method of claim 3 wherein the environmental condition comprises temperature.

5. A system for determining an average of at least one environmental condition, comprising:

a device for measuring the at least one environmental condition, the device comprising a first module having known characteristics dependent on the at least one environmental condition and configured to respond to a radio frequency interrogation of the state of the known characteristic; and

a device for interrogating the measuring device to assess the state of the known characteristics for determining the average of the at least one environmental condition in response thereto.

6. The system of claim 5 wherein the at least one environmental condition comprises temperature.

7. A method of monitoring temperature during an unpowered state of a radio frequency device, the method comprising:

providing a radio frequency device having known characteristics that are dependent on temperature;

exposing the radio frequency device;

interrogating the radio frequency device to determine the state of the known characteristics; and

calculating average temperature of the radio frequency device in response to the state of the known characteristics.

8. The method of claim 7, further comprising determining elapsed time of exposure of the radio frequency device.

9. The method of claim 7 wherein the known characteristics comprise the rate of dissipation of a stored charge.

10. The method of claim 9 wherein the charge is stored in a leaking junction of an integrated device.

11. The device of claim 9 wherein the charge is stored in a super capacitor that discharges at a rate dependent on temperature.

12. The method of claim 9 wherein the charge is stored in a thin-oxide EEPROM having a rate of charge leakage dependent on temperature.

13. The method of claim 9 wherein the charge is stored on a persistent node having a charge leakage dependent on temperature.

14. The method of claim 9 wherein the charge is stored in an electrochemical device that discharges at a rate dependent on temperature.

15. The method of claim 7 wherein the known characteristics comprise an oscillator frequency that varies in response to changes in temperature.

16. The method of claim 7 wherein the known characteristics comprise a variable resistance that changes in response to changes in the temperature.

17. The method of claim 7 wherein the known characteristics comprise magnetic flux that varies in response to changes in temperature.

18. The method of claim 7 wherein the RF device is time-stamped by a reader to determine exposure time of the RF device.

19. A method of monitoring average temperature during an unpowered state of a radio frequency (RF) device, the method comprising:

providing a RF device having known characteristics that are dependent on temperature;

exposing the RF device;

powering the RF device and calibrating the RF device for improving accuracy;

interrogating the RF device to determine the state of the known characteristics; and

calculating average temperature of the RF device in response to the state of the known characteristics.

20. A method of monitoring average temperature during an unpowered state of an RF device, comprising:

providing an RF device comprising a first sensor having known characteristics with a first sensitivity to temperature, and a second sensor having known characteristics with a second sensitivity to temperature that is different than the first sensitivity of the known characteristics of the first sensor;

exposing the RF device;

interrogating the RF device to determine the state of the known characteristics of the first and second sensors; and

calculating elapsed time and temperature of the first and second sensors to determine average temperature.

21. The method of claim 20 wherein the known characteristics comprise rate of dissipation of a stored charge.

22. A device for monitoring temperature, comprising:

a monitoring device configured to change electrical charge state over time and at a rate that varies in response to variations in its temperature; and

an RFID circuit coupled to the monitoring device and configured to transmit the state of the electrical charge in the monitoring device in response to an interrogation signal.