Composite polymer membranes for laser-induced fluorescence thermometry

We demonstrate a modified version of laser-induced fluorescence thermometry (LIFT) for mapping temperature gradients in the vicinity of small photothermal devices. Our approach is based on temperature sensitive fluorescent membranes fabricated with rhodamine B and polydimethylsiloxane (PDMS). Relevant membrane features for LIFT, such as temperature sensitivity, thermal quenching and photobleaching are presented for a range of 25 °C to 90 °C, and their performance is evaluated upon obtaining the temperature gradients produced in the proximity of optical fiber micro-heaters. Our results show that temperature measurements in regions as small as 750 µm × 650 µm, with a temperature resolution of 1 °C, can be readily obtained.