Measurement of fluid viscosity based on pressure-driven flow digital-printed microfluidics

Viscosity is an important characteristic of fluids. Microfluidics has shown significant advantages in the viscosity measurement of biopharmaceuticals, especially in meeting the needs of low sample volumes and accurately controlling microscale fluids. However, the viscosity chip of the traditional straight channel structure has limitations, and the processing technology is also facing challenges. In this study, a variable cross-section microfluidic chip structure was designed and successfully manufactured by photocuring 3D printing technology. A digital-printed (DP) microfluidic viscometer was realized by a pressure-driven flow combined with optical imaging. The device measures the change in sample viscosity with shear rate by recording the change in pressure and flow velocity with time. The whole experiment requires only 25 μl of reagents per time, and the single experiment time is less than 2 minutes, which not only reduces the consumption of samples dramatically, but also improves the efficiency of the experiment significantly. Compared with commercial viscometers, our measurements are accurate and capable of supporting non-Newtonian fluids. The proposed platform provides good cost-effectiveness and operational simplicity and lays the methodological foundation for viscosity measurements of more complex properties of fluids.