Optical Tweezers-Assisted Cross-Correlation Analysis for a Non-intrusive Fluid Temperature Measurement in Microdomains

Chih-Ming Cheng, Ming-Chih Chang, Yu-Fen Chang, Wei-Ting Wang, Chien-Ting Hsu, Jing-Shin Tsai, Chia-Yeh Liu, Chien-Ming Wu, Keng-Liang Ou, and Tzu-Sen Yang
An image-based approach to predict the fluid temperature in microfluidic flow cell is presented. We apply Fourier-based cross-correlation processing to determine the lateral displacement of the optically trapped bead; therefore, both the mean square displacement (MSD) and the diffusion coefficient (D) can be obtained. On the other hand, applying the Stokes–Einstein equation, together with Faxen's law correction, the theoretical relation showed that D is proportional to (T/η), where Tand η are temperature and temperature-dependent fluid viscosity, respectively. Hence, the fluid temperature can be determined by MSD-based thermometry.

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