Composite polymer membranes for laser-induced fluorescence thermometry

Abstract

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 x 650 µm, with a temperature resolution of 1 °C, can be readily obtained.

Photomechanical Polymer Nanocomposites for Drug Delivery Devices

“…The temperature of the samples was adjusted with a PID controller and a CCD camera with a notch filter were used for acquiring the temperature dependent fluorescence intensity. Further details of the LIFT system can be found elsewhere [ 55 ]. A data acquisition (DAQ) system is connected to a PC where a virtual instrument (VI) programmed in LabVIEW was used to simultaneously control and acquire data and images of the experiment (see Figure 11 b).…”

“…This fluorescent and temperature-sensitive membrane was used to observe the temperature gradient on the flat surface of the cylinder. The experimental setup used for these purposes is shown in Figure 11 b, and the methodology, calibration, and image processing have been described by Gonzalez-Martinez et al [ 55 ]. This process yields images of the temperature maps corresponding to the surface of the cylinder that is irradiated with an NIR laser diode ( = 975 nm, 5–290 mW).…”

Luminescent Polymer Composites for Optical Fiber Sensors

“…A direct relation between the temperature and the intensity of the fluorescence emitted by the PDMS-YbEr membranes can be obtained by means of image analysis. For this task, we used a technique originally developed for laser-induced fluorescence thermometry (LIFT) to acquire temperature maps with micron-scale spatial resolution [ 22 ]. Briefly, images were acquired at different temperatures using the setup shown in Figure 3 ; these were subsequently analyzed through direct comparison between a reference image and images obtained at prescribed temperatures.…”

“…Briefly, images were acquired at different temperatures using the setup shown in Figure 3 ; these were subsequently analyzed through direct comparison between a reference image and images obtained at prescribed temperatures. In our case, the reference image was obtained at room temperature, and its average intensity was used to normalize the average intensities acquired at specific temperatures set with the TEC (see [ 22 ] for details). This procedure allows for the obtention of a calibration curve for each membrane, yielding a plot of normalized intensity as a function of temperature.…”

“…Thus, the membranes do not show evidence of thermal bleaching, nor is photobleaching evident, at least under our experimental conditions. These features are of interest for fluorescent thermometry, which typically relies on fluorescent dyes such as Rhodamine B (RhB) as the temperature-sensitive material (see [ 22 ] and references therein). Photobleaching and thermal bleaching hinder the performance of RhB in fluorescent thermometry applications, requiring recalibration procedures over time.…”