Abstract: Biochemical reaction in microfluidic chip is sensitive to temperature. Temperature precise control in a small size device requires the temperature measurement with high measurement precision. Traditional temperature measurement method usually measures the voltage drop of the thermistor, which is excited by a constant current source. This method requires the constant current source with high precision and stability. The output of the constant current source is influenced by environmental factors, resulting in a larger measurement error. To solve this problem, a proportion method, a two-layer filtering algorithm, and a power management technique were applied to improve the temperature measurement precision. The proportion method can reduce the low frequency fluctuation error. The two-layer filtering algorithm can reduce the high frequency fluctuation error further. The power management technique used can improve the system stability. Through testing the temperature measurement system built, the experimental results show that the fluctuation error can be significantly decreased from 0.5 ?C to 0.2?C.

Key words: microfluidic chip, temperature measurement, proportion method, two-layer filtering algorithm, fluctuation error