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Development of a temperature monitoring module for fully automated ultra-deep temperature storage

More and more biobanks invest in a fully automated ultra deep temperature storage robot to store their samples automatically with a high security standard (e.g. Hamilton BiOS or comparable devices). To measure and estimate the temperature gradients, to which the samples are exposed in the storage system, the Hannover Unified Biobank HUB), the central biobank of the Hannover Medical School (MHH), develops a temperature monitoring module. This modul can measure the real sample temperatures in a sample tube during the various storage processes in the repository and store the correlating data.

Method: The measuring module consists of several compoments (see fig.1.). This is at first the temperature logger “c\temp dlt” of the company Marathon. It contains a recorder and a temperature sensor and a storage box of the company Thermo Scientific. The software "MDAS Pro" provided by the manufacturer for MS-Windows™ based system allows the configuration of the logger, as well as the readout of the measured values. For this, a suitable temperature recorder was installed in a storage box and inserted the corresponding temperature sensor in a contained sample tubes. To detect the temperature variations during passing through the various areas of the storage robot (Hamilton BiOS), the sensor was adjusted in a measurement range of seconds. The various stations of the repository, through which the measuring module is passed through, are the input and output station, the picking station and the transfer and storage area. Here, the operating temperature of the storage units and the picking station is at -80°C. The sample transfer takes place at a compartment cooled down to -20°C. The special challenge in the development of the measuring unit is the necessary cold tolerance of temperature logger. Conventional measurement modules are not suitable for cryogenic temperature range (here -80°C) and for the short measurement intervals of max. 5 sec.



Figure 1:
Components of the temperature monitoring modul are built up of  a recorder und a temperature sensor (left) which are positioned in a sample storage box (top right). The temperature sensor is located in a single sample tube (down right).


Results: Integreted in the sample box, the measuring unit can be safely bring into the storage robot, the temperature profile could measured in the sample tube and the data were stored at the data recorder. The internal sample management system of the robot was successful adapted to the modified sample box. So it was ensured that during the transfer of the sample tubes no damage to the automatic storage can be caused by of the manipulated box. Monthly the storage box will be inserted into the BiOS. It passes through a fixed path in the robot, which contains among other things a scan of the box and the picking of multiple samples. This allows mapping a typical temperature profile which is compared with a previously created reference profile. Through this potential problems can be identified and appropriate measures can be initiated early. The profile data are recorded in a database and are available for further evaluation. The results will also be integraded in the qualification of the automated repository and will be the first steps in the direction of a validation of the IT system of the automated storage processes.