TVIS augmented by the acquisition of fibre optic temperature sensors

The Pharmaceutical Technologies group has recently acquired a fibre optic temperature sensor from INFAP GmbH (München, Germany).

Until now, the calibration of the TVIS response (i.e. the peak frequency, FPEAK) and peak magnitude, C″PEAK) against temperature, for a vial containing the frozen liquid, has relied on the triangulation of temperature measurements from thermocouples or RTD temperature sensors placed in the nearest neighbour vials. Placing the thermocouple directly in the TVIS vial is not an option as the metallic sensor provides a short circuit to ground and introduces a strong distortion to the TVIS spectrum, which is particularly noticeable at low frequency (see Fig. 1). Inevitably, having to rely on temperature assessments from the nearest neighbour vials, introduces a degree of uncertainty, where the uncertainty is assumed to be equal to the differences in the temperatures determined within a minimum of 3 of the nearest neighbour vials.

With Fibre Bragg Grating (FBG) Technology from INFAP GmbH, it is now possible to measure the temperature directly within the TVIS vial, and at a precise location within the fill volume, without distorting the impedance spectrum. The benefit will be a more precise calibration of the TVIS technology and improved analysis of critical events, such as ice nucleation temperatures, eutectic crystallization, glass formation, and product collapse.

For more information about the Fibre Optic Temperature Sensor contact:

Manfred Resch (CEO),INFAP GmbH, Fürstenriederstr. 279a, 81377 München, Germany

Fig. 1 (A) Real and (B) imaginary spectra from a TVIS vial containing water (plain vial) and the same vial with a TC probe inserted into the liquid (labelled TC) demonstrating the strong distortion to the spectrum from the leakage of current to ground via the TC