Advances in Fluid Viscosity Measurement Technologies

Viscosity is a critical property of fluids that quantifies their resistance to deformation. Selecting an appropriate viscosity measurement method is essential for industrial production and scientific research. With the increasing application of microfluidics in fields such as biomedicine, new energy, and advanced materials, innovative methods for microfluidic viscosity measurement have emerged. This paper reviews the current progress in fluid viscosity measurement technologies, categorizing them into traditional macroscopic fluid measurement methods and emerging microfluidic measurement methods. Traditional macroscopic methods, including rotational viscometers, oscillatory viscometers, falling ball viscometers, and ultrasonic viscometers, are analyzed in terms of their structures, measurement principles, advantages, disadvantages, and current developments. For microfluidic viscosity measurement, cutting-edge techniques such as micro-electro-mechanical system (MEMS)-based viscometers, optically based viscometers, droplet-based viscometers, and paper-based microfluidic viscometers are introduced and evaluated regarding structural characteristics, measurement accuracy, and principles. Comparisons are made between traditional and microfluidic viscometers to highlight their unique strengths. The findings indicate that while traditional viscometers remain the primary choice for large-scale industrial applications, microfluidic viscometers are gaining attention due to their advantages, such as minimal sample requirements, high efficiency, low cost, and compact size. This review provides a comprehensive reference for researchers and practitioners to select the most suitable viscosity measurement technique for specific applications.