Microfluidic temperature sensor based on temperature-dependent dielectric property of liquid**Project supported by the Natural Science Foundation of Zhejiang Province, China (Grant No. LQ19F010007), the National Natural Science Foundation of China (Grants Nos. 61901146 and 61874038), and the Smart City Collaborative Innovation Center of Zhejiang Province, China.

Abstract

We propose a low-cost compact microfluidic temperature sensor by virtue of the temperature-dependent permittivity of liquid. The sensor is composed of a coplanar waveguide (CPW) transmission line loaded with three resonators and a microfluidic plate with three channels. The resonant frequency of each resonator relies on the temperature-dependent dielectric property of liquid in corresponding channel, which therefore can be used to extract the temperature. The proposed sensor features a compact size and low cost since it requires only micro fluid volume instead of additional electronic components to produce significant frequency shift with changing temperature. Moreover, it exhibits decent accuracy and stability in a temperature sensing range from 30 °C to 95 °C. A theoretical analysis of the sensor is provided, followed by the detailed characterization method, and a prototype is designed, manufactured, and measured to verify the theoretical analysis.