A new way to measure viscosity in droplet-based microfluidics for high throughput analysis (original) (raw)

Nanoliter droplet viscometer with additive-free operation

Lab on a Chip, 2013

Measurement of a solution's viscosity is an important analytic technique for a variety of applications including medical diagnosis, pharmaceutical development, and industrial processing. The use of dropletbased (eg, water-in-oil) microfluidics for viscosity measurements allows nanoliter-scale sample volumes to be used, much smaller than those either in standard macro-scale rheometers or in single-phase microfluidic viscometers.

Droplet microfluidics in (bio)chemical analysis

The Analyst, 2014

Droplet microfluidics may soon change the paradigm of performing chemical analyses and related instrumentation. It is not only the analysis scale and possibility for sensitivity improvement, reduced consumption of chemical and biological reagents, but also the vast increase of the speed in performing a variety of unit operations. At present, microfluidic platforms can reproducibly generate monodisperse droplet populations at kHz or higher rate with droplet sizes suitable for high-throughput experiments, single-cell detection or even single molecule analysis. In addition to being used as microreactors with volume in the micro-to femtoliter range; droplet based systems have also been used to directly synthesize particles and encapsulate biological entities for biomedicine and biotechnology applications. This minireview summarizes the various droplet microfluidics operations and applications for (bio) chemical assays described in the literature during the past few years.

Electronic drop sensing in microfluidic devices: automated operation of a nanoliter viscometer

Lab on a Chip, 2006

We describe three droplet sensing techniques: a digital electrode, an analog electrode, and a thermal method. All three techniques use a single layer of metal lines that is easy to microfabricate and an electronic signal can be produced using low DC voltages. While the electrode methods utilize changes in electrical conductivity when the air/liquid interface of the droplet passes over a pair of electrodes, the thermal method is based on convective heat loss from a locally heated region. For the electrode method, the analog technique is able to detect 25 nL droplets while the digital technique is capable of detecting droplets as small as 100 pL. For thermal sensing, temperature profiles in the range of 36 °C and higher were used. Finally, we have used the digital electrode method and an array of electrodes located at preset distances to automate the operation of a previously described microfluidic viscometer. The viscometer is completely controlled by a laptop computer, and the total time for operation including setup, calibration, sample addition and viscosity calculation is approximately 4 minutes.

Microfluidic dynamic system for biological fluids viscosity measurements

CAS 2005 Proceedings. 2005 International Semiconductor Conference, 2005., 2005

The purpose of this research was to model, design and fabricate a microdynamic system, using a four masks silicon micromachining process and sacrificial layers technique. The measurement principle is the detection of the rotation of a micromachining polysilicon gear wheels system with external diameters of 250 µm, 200 µm, 160 µm and 3 µm thickness combine the undercut and refill technique with pin-joint bearing permitting the fabrication of bushings that can be used, for example, to elevate the rotor away from the silicon surface. The microfluidic dynamic system consists of a gear wheels system, an electromagnetic micropump and a magnetic controller. Each device is fabricated by silicon micromachining technology and tested to obtain the specific characteristics.

Open-source tool for real-time and automated analysis of droplet-based microfluidic

Lab on a Chip, 2023

Droplet-based microfluidic technology is a powerful tool for generating large numbers of monodispersed nanoliter-sized droplets for ultra-high throughput screening of molecules or single cells. Yet further progress in the development of methods for the real-time detection and measurement of passing droplets is needed for achieving fully automated systems and ultimately scalability. Existing droplet monitoring technologies are either difficult to implement by non-experts or require complex experimentation setups. Moreover, commercially available monitoring equipment is expensive and therefore limited to a few laboratories worldwide. In this work, we validated for the first time an easy-to-use, open-source Bonsai visual programming language to accurately measure in real-time droplets generated in a microfluidic device. With this method, droplets are found and characterized from bright-field images with high processing speed. We used off-the-shelf components to achieve an optical system that allows sensitive image-based, label-free, and cost-effective monitoring. As a test of its use we present the results, in terms of droplet radius, circulation speed and production frequency, of our method and compared its performance with that of the widely-used ImageJ software. Moreover, we show that similar results are obtained regardless of the degree of expertise. Finally, our goal is to provide a robust, simple to integrate, and user-friendly tool for monitoring droplets, capable of helping researchers to get started in the laboratory immediately, even without programming experience, enabling analysis and reporting of droplet data in real-time and closed-loop experiments.

Label-Free Sensing in Microdroplet-Based Microfluidic Systems

Chemosensors, 2018

Droplet microfluidic systems have evolved as fluidic platforms that use much less sample volume and provide high throughput for biochemical analysis compared to conventional microfluidic devices. The variety of droplet fluidic applications triggered several detection techniques to be applied for analysis of droplets. In this review, we focus on label-free droplet detection techniques that were adapted to various droplet microfluidic platforms. We provide a classification of most commonly used droplet platform technologies. Then we discuss the examples of various label-free droplet detection schemes implemented for these platforms. While providing the research landscape for label-free droplet detection methods, we aim to highlight the strengths and shortcomings of each droplet platform so that a more targeted approach can be taken by researchers when selecting a droplet platform and a detection scheme for any given application.

MEMS sensors for density–viscosity sensing in a low-flow microfluidic environment

Sensors and Actuators A: Physical, 2008

Technologies based on micro electro mechanical systems (MEMS) present advantages for downhole oilfield applications since they enable the fabrication of small sensors with fast response times. Furthermore, by incorporating MEMS sensors in a microfluidic environment it would be possible to make representative measurements of fluid properties with a sample volume of no more than 1 L and flow rates on the order of 1 L per minute. Here, we fabricate a set of resonating beams with millimetre-scale lengths and micron-scale cross-sections to demonstrate the feasibility of resonance measurements with three different techniques. In addition, we demonstrate how the quality factor and resonance frequency can be measured to calculate the fluid viscosity and density. The effect of flow rate on the sensor is shown to be minimal in microfluidic channels, presumably due to the small cross-sectional area of the beams. These sensors are compatible with the high pressure environments found downhole.

A biodynamic microsystem for fluids viscosity measurements

Journal of Physics: Conference Series, 2006

The purpose of this research was to model, design and fabricate a biodynamic analysis microsystem required for determination of various molecular transport properties of the biological fluids. In order to achieve this, a lab-on-a-chip device was fabricated. The microfluidic system developed satisfies the objectives for the study of microcirculation and characterization of cell rheological properties, functions and behaviour. The measurement principle of the viscosity of biological fluids is based on the detection of the rotation of a polysilicon gear-wheels system. The gear-wheels have external diameters of 250 μm, 200 μm, 160 μm and 3 μm thickness. The micromachining process combines the undercut and refill technique with pin-joint bearing permitting the fabrication of bushings that were used to elevate the rotor away from the silicon surface. The testing of the microfluidic dynamic system was performed using electromagnetic micropumps and magnetic controllers. Each device was fabricated by silicon micromachining technology and tested to obtain the specific characteristics.