Design and Modeling of Vanadium Dioxide-Based High-Sensitivity Microfluidic Calorimetric Sensors

Accurate measurement of microfluidic flow with high sensitivity is critical across numerous industries and applications. The calorimetric microflow sensor attracts attention among different MEMS flow sensors due to its excellent performance at low flow rates. To further improve the sensitivity and meet the nL/min to
$\boldsymbol{\mu} \mathbf{L}/\mathbf{min}$
detection demand, we employed the metamaterial vanadium dioxide (VO
2
) as a thermally sensitive material of ultra-high temperature-coefficient-of-resistance (TCR) in the phase change region. Meanwhile, the significant and intricate temperature-dependent hysteresis behavior is thoroughly investigated. Hence, the major and minor hysteresis models of VO
2
based on the physical mechanisms and the Preisach model are established, respectively, which enables a comprehensive analysis and performance evaluation of VO
2
-based calorimetric microflow sensor using finite element analysis (FEA). The results show that the proposed sensor achieves a sensitivity of
$\mathbf{0.456} \mathbf{V}/(\boldsymbol{\mu} \mathbf{L}\cdot\mathbf{min}^{-\mathbf{1}})$
in the linear range of 0 to
$\mathbf{0.3}\ \boldsymbol{\mu} \mathbf{L}\cdot\mathbf{min}^{-\mathbf{1}}$
, which is 83.82 times higher than the Pt-based calorimetric sensor and 5.17 times higher than the VO
2
-based anemometric sensor. This work provides a novel approach for designing high-performance thermal microflow sensors using metamaterials with hysteresis behavior.