Biological sample storage and monitoring system

1. A method of maintaining a thermal history of biological samples stored in a temperature-controlled sample storage system, the system including one or more containers each storing one of the samples; one or more storage objects each housing one or more containers or one or more second storage objects; one or more structures defining a temperature-controlled storage environment and housing the one or more storage objects; machine readable tags each of which is associated with a separate container and storage object, each tag encoding an identification code and having a temperature-dependant characteristic; and an interrogator for reading the identification code and the temperature-dependant characteristic, the method including the steps of:

a) monitoring the temperature in each temperature-controlled storage environment;

b) interrogating a database to determine one or more specific storage objects housing a particular container within a specific structure;

c) locating one of the specific storage objects housing the particular container by reading the identification code of the machine-readable tag associated with that specific storage object;

d) reading the value of the temperature dependant characteristic of the machine-readable tag associated with the specific storage object located in step c);

e) storing the read identification code and value of the temperature-dependant characteristic in the database;

f) removing the particular container, or another of the specific storage objects in which the particular container is stored, from the storage object located in step b);

g) repeat steps c) to f) until the particular container is removed; and

h) returning the one or more specific storage objects to the specific structure.

2. A method according to claim 1 , and further including the step of:

determining whether any of the values of the temperature dependant characteristic exceed a temperature limit.

3. A method according to claim 2 , and further including the step of:

triggering an alarm condition when the value exceeds the temperature limit.

4. A method according to claim 1 , and further including the step of:

determining whether any of the values of the temperature dependant characteristic exceeds any of a plurality of temperature limits.

5. A method according to claim 4 , and further including the step of:

triggering an alarm condition when the value exceeds any one of the temperature limits.

6. A method according to claim 5 , and further including the step of:

providing a different response depending upon which of the temperature limits are exceeded.

7. A method according to claim 1 , and further including the step of:

prior to step c), locating the specific structure housing the particular container by reading the identification code of the machine-readable tag associated with that structure.

8. A method according to claim 1 , and further including the step of retrievably housing each container in the structure by:

reading the identification code of the machine-readable tag associated with each container;

reading the identification code of the machine-readable tag associated with each storage object in which the container is housed;

storing the read identification codes in the database for subsequent interrogation.

9. A method according to claim 1 , wherein each machine readable tag includes a plurality of resonant members.

10. A method according to claim 9 , wherein at least one of the resonant members has the temperature-dependant characteristic.

11. A method according to claim 9 , wherein the resonant members have different resonant frequencies from each other.

12. A method according to claim 9 , wherein the resonant members are vibrated by a Lorentz-type force on application of an excitation signal to the tag.

13. A method according to claim 9 , wherein the temperature-dependant characteristic is a shift in resonant frequency of the at least one resonant member as a function of temperature.

14. A method according to claim 9 , wherein a first coil antenna is coupled to the plurality of resonant members, wherein the interrogator includes signal processing circuitry and a reading head in communication with signal processing circuitry, and wherein the reading head including an interrogation coil, the method further including the steps of:

positioning the interrogation coil proximate the coil antenna; and

generating an interrogation signal in the interrogation coil so as to induce an excitation signal in the coil antenna.

15. A method according to claim 14 , wherein the step of positioning the interrogation coil proximate the coil antenna includes locating one of the interrogation coil and the antenna coil inside the other during tag reading.

16. A method according to claim 15 , wherein one or both of the interrogation coil and the antenna coil have a helical form.

17. A method according to claim 14 , wherein the step of positioning the interrogation coil proximate the coil antenna includes concentrically locating the interrogation coil and the antenna coil during tag reading.