Biological sample storage and monitoring system

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.