Near-infrared measurement of water temperature near micro-magnetic particle layer in a fluidic channel under induction heating

This paper presents an experimental method for measuring the water temperature near micro-magnetic particle (MMP) layers in a fluidic channel under induction heating. This method is based on the temperature dependence of the spectrum of the nu(1) + nu(3) absorption band of water in the near-infrared (NIR) region. The absorbance images at the wavelength of 1412 nm, which is the most temperature-sensitive wavelength in the band, were obtained through a U-shaped channel with an optical path length of 1 mm using a narrow-bandpass filter and an NIR camera. An MMP layer was formed on the inner surface of the channel by an external strong permanent magnet and then heated inductively by applying a 760-kHz magnetic field. The temperature distribution of water was found to depend on the heating time, heating power level, and MMP layer thickness (0.5, 0.6, and 1.0 mm). The maximum increase in temperature near the MMP layer was approximately 5 degrees C, and the temperature resolution was 0.2 degrees C. A numerical simulation was used to verify the measured temperature profiles then apply the residual fitting method to determine the heat generation rates (HGRs) of the MMPs. The HGRs were independent of the heating time, and varied consistently with the heating power level. This method is useful for the quantitative understanding and control of temperature fields in applications that use MMPs for chemical reactions and cell/tissue therapy.