3D-Printed Capillary Circuits for Calibration-Free Viscosity Measurement of Newtonian and Non-Newtonian Fluids

Abstract

Measuring viscosity is important for the quality assurance of liquid products, as well as for monitoring the viscosity of clinical fluids as a potential hemodynamic biomarker. However, conventional viscometers and their microfluidic counterparts typically rely on bulky and expensive equipment, and lack the ability for rapid and field-deployable viscosity analysis. To address these challenges, we describe 3D-printed capillary circuits (3D-CCs) for equipment- and calibration-free viscosity measurement of Newtonian and non-Newtonian fluids. A syringe, modified with an air chamber serving as a pressure buffer, generates and maintains a set pressure to drive the pressure-driven flows of test fluids through the 3D-CCs. The graduated fluidic chambers of the 3D-CCs serve as a flow meter, enabling simple measurement of the flow rates of the test fluids flowing through the 3D-CCs, which is readable with the naked eye. The viscosities of the test fluids can be simply calculated from the measured flow rates under a set pressure condition without the need for peripheral equipment and calibration. We demonstrate the multiplexing capability of the 3D-CC platform by simultaneously measuring different Newtonian-fluid samples. Further, we demonstrate that the shear-rate dependence of the viscosity of a non-Newtonian fluid can be analyzed simultaneously under various shear-rate conditions with the 3D-CC platform.

Functional microfluidics: theory, microfabrication, and applications

“…A smart pipette generates controlled shear rate conditions to operate the 3D-printed microfluidic circuit for whole blood analysis (figure 16(a)). Subsequently, Oh and Choi [282] measured the calibration-free viscosity of both Newtonian and non-Newtonian fluids (figure 16(b)). In addition, Yafia et al [283] presents a microfluidic chain reaction (MCR) system that allows for the automated control of sequential fluids release for various applications.…”

A Review of Microfluidic Devices for Rheological Characterisation

“…In addition to the coflow geometries featuring a reference fluid and the sample, other microfluidic rheometers allowed viscosity measurements via the tracking of an air-liquid interface. Oh and Choi [29] introduced a 3D-printed capillary circuit (Figure 3e,f) to measure the shear viscosity of several glycerol (Newtonian) and xanthan gum (non-Newtonian) aqueous solutions. While flowing in the capillary circuit, liquid displaced the air initially contained in the capillaries; the flow rate could be measured by tracking the fluid-air interface thanks to a small scale.…”

3D-Printed Microfluidics and Potential Biomedical Applications

“…The present research offers an important technological approach to the production of low-cost microfluidic tools for efficient reagent mixing in microscale biochemical detection systems. Oh et al developed and fabricated a 3D-printed blood viscosity analysis (Oh and Choi, 2018). Viscosity measurement is essential for the quality assurance of liquid products, as well as for monitoring the viscosity of clinical fluids as a potential hemodynamic biomarker.…”