Two-color laser-induced fluorescent thermometry for microfluidic systems

Abstract

The feasibility of implementing a two-color laser-induced fluorescence (LIF) technique to study thermal transport at the microscale is investigated. Temperature-sensitive (Rhodamine B) and temperature-insensitive (Sulforhodamine-101) fluorescent dyes are used in tandem to determine fluid temperature with high accuracy and low noise using a pulsed Nd:YAG laser as an illumination source. While the fluorescence intensity of the temperature-sensitive dye is proportional to temperature, it is also biased by variations in the illuminating intensity. Therefore, a second temperature-insensitive dye is required to compensate for such biases. Calibration of the two-color LIF system using the RhB-SR101 dye combination in ethanol and water yields temperature sensitivities of −1.5% K −1 and −2.7% K −1 , respectively, with volumetric illumination from an Nd:YAG laser. The feasibility of this methodology for conducting temperature measurements is explored by measuring a steady-state temperature gradient maintained across a microfluidic channel array by two large hot and cold reservoirs. These measurements reveal that the mean steady-state temperatures in the microchannels are within ±0.4 • C and ±0.3 • C of the predicted temperatures with ethanol and water as the solvents, respectively, with a spatial resolution of 22.2 × 22.2 μm. The experimental uncertainties in the measurements using the RhB-SR101 dye combination are ±0.48-0.59 • C and ±0.41-0.49 • C for ethanol and water, respectively.

The saturation of the fluorescence and its consequences for laser-induced fluorescence thermometry in liquid flows

“…2). Also, for most of them, an application to temperature measurement in water solutions has already been reported (Bruchhausen et al 2005;Coppeta and Rogers 1998;Dunand et al 2012;Natrajan and Christensen 2009;Sakakibara and Adrian 1999;Sutton et al 2008). …”

CdSe/ZnS quantum dot fluorescence spectra shape-based thermometry via neural network reconstruction

“…Fluorescent dyes have been used in many instances including labeling structures in cells, 2 single photon imaging, 3 and as temperature sensors, relating the individual spectral features such as peak intensity (PI), peak wavelength (PW or PWL), or the ratio of different spectral peaks, 4 as well as fluorescent lifetime measurements. 5 Specifically, Rhodamine B dye has been used as a non-contact temperature sensor in microfluidic devices, 6,7 to probe the surface temperature between two plates, 8 and as an additive in polydimethylsiloxane (PDMS) to measure the thermal conductivity of carbon nanotubes. 9,10 However, all of these applications assumed a linear relation between a single spectral feature (usually the peak intensity) and the temperature.…”

Modeling Cumulative Damage to Flow Surfaces and Assessing its Impact on Wall Turbulence

“…Rhodamine B is a chemical compound and a dye, often used as a tracer dye or staining fluorescent dye. The red to violet powder has a maximum emission intensity from 550 − 570 nm when excited by laser light at 532 nm (Natrajan and Christensen, 2009) Clearly, the reflections viewed in figure 2.7(a) compared to that in figure 2.7(b) provide evidence that the Rhodamine B acts to suppress incident laser light reflections on the roughness surfaces.…”