Sputtered thermocouple for lyophilization monitoring

This paper describes development and characterization of thin film thermocouples to be used as a non-perturbating solution to follow the freeze-drying process of pharmaceutical chemicals. Pharmaceutical chemicals are routinely produced by means of freeze-dryers with excellent results, however the drying process is slow requiring days to complete and this increases the product cost. To optimize the process, reducing the drying time, this must be carried out close to the maximum allowed temperature. A monitoring system able to continuously monitor the product temperature during the drying could greatly reduce the damage risk, but actual sensors are too invasive to permit a reliable measurement and radiation remote systems cannot be used. This paper describes the results obtained by developing thermocouples with sub-micrometric thickness which can be embedded into the vial walls without significatively altering the wall thickness and properties. Prototypes of the proposed thermocouples have been realized and successfully tested.