Capillary-based micro-optofluidic viscometer

Abstract

In this study, a capillary-based micro-optofluidic viscometer, which is capable of measuring dynamic viscosity in a range of 0.5 mPa s-50 mPa s with only a small volume of liquid (26 µl) in just a few seconds (less than 15 s for most of the samples used) with an acceptable accuracy (99.56%), has been designed, fabricated, and tested. This device consists of two different parts, namely a poly(methyl methacrylate) (PMMA) microfluidic chip and an electro-optical detection system. The viscometer determines viscosity by measuring the time that the liquid travels between two specific points of a rectangular microchannel. The microchannel has been micro-milled on a PMMA substrate, which has been bonded to another PMMA sheet. The fluid flow inside the microfluidic chip has been created by the capillary driven flow; hence, there is no need for any external devices to generate fluid flow. The resolution of this microviscometer is approximately 0.001 mPa s. An ADC circuit has been added to the electro-optical detection system, which is an optically-activated stopwatch circuit, to enhance accuracy, sensitivity, resolution, and to make this viscosity measurement device applicable and efficient for a wide range of applications. This integrated microviscometer automatically notices entry of liquid and completion of the experiment, and finally gives the result. In this study, only Newtonian fluids were tested via this microviscometer, but this device is also capable of measuring non-Newtonian liquids. This portable microviscometer has applications in different fields such as point-of-care diagnosis, chemical and food industries, pharmaceutical industries, research laboratories, etc.

A Review of the Real-Time Monitoring of Fluid-Properties in Tubular Architectures for Industrial Applications

“…The optical-capillary is based on measuring the fluid velocity using optical methods for determining the viscosity [ 193 ]. They are mainly using the support of optics, such as microscopes [ 152 ], digital cameras [ 194 ], lasers, and photodiodes [ 195 ], to determine the required time for the fluid to pass between two points separated by a known distance. For example, a digital camera placed above a transparent microchannel, video recording the fluid flow, and calculating the displacement time between two chosen points [ 161 ].…”

Design and Fabrication of Capillary-Driven Flow Device for Point-Of-Care Diagnostics

“…The red colour intensity increased with time (Figure 4a), and the colour intensity levels variability was found to be 5% (%RSD) between the 15 microchannels and 9% (%RSD) between the microchips (n = 3). Figure 4c shows the graph of colour intensity change at different times (3,6,12,18,24,30, 60 and 120 s) for the 15 microchannels in a single microchip. Biosensors 2020, 10, x FOR PEER REVIEW 5 of 8 Furthermore, the presence of β-lactamase, an indicator of antimicrobial resistance [23,24] was tested by dipping nitrocefin-coated microchannels into a β-lactamase solution (Abcam, recombinant Escherichia coli β-lactamase protein) and DI water samples.…”

“…The red colour intensity increased with time ( Figure 4a), and the colour intensity levels variability was found to be 5% (%RSD) between the 15 microchannels and 9% (%RSD) between the microchips (n = 3). Figure 4c shows the graph of colour intensity change at different times (3,6,12,18,24,30, 60 and 120 s) for the 15 microchannels in a single microchip. A smartphone (iPhone XR) was used to capture images of the microchip under external light, which could add variations in the light signal of the different microchannels.…”

“…The authors numerically modelled and tested polydimethylsiloxane (PDMS) microchips and validated the flow inside the capillaries by tracking the fluid meniscus. Capillary-driven flow devices were also fabricated [5,6] to measure the viscosity of a fluid based on capillary action in microchannels. For example, Lee et al [5] developed a capillary-driven flow microfluidics device to measure zebrafish blood viscosity in Biosensors 2020, 10, 39 2 of 7 microchannels.…”

Passive mixing rate of trapped squeezed nanodroplets—A time scale analysis

“…Recent advances in micro and nanofluidics have facilitated integrated operations on chip toward various physical, chemical, and biological applications (Bamshad et al, 2017(Bamshad et al, , 2018. The mixing of micro and nanodroplets is an important operation in different aspects of micro and nanofluidics such as in μTAS (micro total analysis systems) and lab-on-a-chip.…”