title: Temperature imaging of water in a microchannel using thermal sensitivity of near-infrared absorption.
abstract: This paper presents a remote and preparation-free method of temperature imaging of aqueous solutions in microchannels of microfluidic chips. The principle of this method is based on the temperature dependency of the near-infrared (NIR) absorption band (ν(2) + ν(3) band) of water. Temperature images were constructed from absorbances in a narrow wavelength range including 1908 nm, the most sensitive to temperature in the band, measured by using an NIR camera and an optical narrow-bandpass filter. Calculation and calibration results demonstrated a linear relationship between the absorption coefficient and temperature with a temperature coefficient of 1.5 × 10(-2) K(-1) mm(-1). Temperature images of 50 μm thick water in a Y-shaped PDMS microchannel locally heated by a neighboring hot wire were obtained, in which thermal diffusion processes in the microchip were visualized. Temperature resolution was estimated to be approximately 0.2 K according to the temperature coefficient and noise level.
authors.affiliation: Department of Applied Quantum Physics and Nuclear Engineering, Faculty of Engineering, Kyushu University, Higashi-ku, Fukuoka, Japan. kakuta@nucl.kyushu-u.ac.jp
authors.forename: Naoto
authors.initials: N
authors.lastname: Kakuta
authors.forename: Yuko
authors.initials: Y
authors.lastname: Fukuhara
authors.forename: Katsuya
authors.initials: K
authors.lastname: Kondo
authors.forename: Hidenobu
authors.initials: H
authors.lastname: Arimoto
authors.forename: Yukio
authors.initials: Y
authors.lastname: Yamada
mesh_terms: D000042:Absorption; D004129:Dimethylpolysiloxanes / Q000737:chemistry; D006358:Hot Temperature; D057446:Hydrodynamics; D046210:Microfluidic Analytical Techniques / Q000295:instrumentation*; D013055:Spectrophotometry, Infrared / Q000295:instrumentation*; D013696:Temperature; D035501:Uncertainty; D014867:Water / Q000737:chemistry*
chemical_list: D004129:Dimethylpolysiloxanes; D014867:Water; C013830:baysilon