Novel fibre optic temperature sensors based on thermoresponsive polymers

In this paper we present the development of a novel fibre optic temperature sensor based on thermoresponsive polymers. The principle of our invention that is already applied for a patent is based on the detection of the optical power that is transmitted through an optical fibre, whilst a temperature sensitive element is integrated in this fibre. This element comprises a water-based solution wherein a thermoresponsive polymer is dissolved. The solution is clear like pure water when the temperature is below a specific, material-dependent temperature threshold. When the temperature exceeds this threshold, the solution becomes opaque, whilst this change is completely reversible when the temperature is set back to a value below this threshold. As a consequence, the optical transmission is a function of the temperature. This effect can be exploited for a measurement of the temperature by measuring the transmitted optical power in the fibre.