Integrated microfluidic viscometer equipped with fluid temperature controller for measurement of viscosity in complex fluids

Abstract

In the study described herein, a microfluidic viscometer equipped with fluid temperature controller is proposed for measuring the viscosity of complex liquids containing cells or particles. The microfluidic viscometer is composed of a microfluidic device and a fluid temperature controller. The microfluidic device has two inlets, for the introduction of the sample and reference fluids, respectively, and a spacious diverging channel with a large number of identical indicating channels. A fluid temperature controller, which contained a Peltier chip, micro thermocouples, and a feedback controller, is applied for the consistent control of the temperature of the fluids in the microfluidic channels. For accurately identifying fluid viscosity, an effective design criterion is discussed using an enhanced mathematical model for complex fluid networks. The accuracy of the proposed model is sufficiently investigated via numerical simulations as well as experimental measurements. As performance demonstrations, pure liquids [five different concentrations of SDS (Sodium Dodecyl Sulphate)] and complex fluids (four different blood samples) were used to evaluate the performance of the proposed microfluidic viscometer. This investigation indicated that the proposed microfluidic viscometer is capable of accurately and simply measuring both Newtonian and non-Newtonian fluids, even without the need for calibration procedures, and artifacts faced with a conventional viscometer. We therefore conclude that our proposed microfluidic viscometer has considerable potential for the precise and easy measurement of complex fluid viscosity.