AN OPTICAL MICRO-FLUIDIC VISCOMETER (original) (raw)
Related papers
Measurement of the microscopic viscosities of microfluids with a dynamic optical tweezers system
Laser Physics, 2014
Viscosity coefficients of microfluids-Newtonian and non-Newtonian-were explored through the rotational motion of a particle trapped by optical tweezers in a microflute. Unlike conventional methods based on viscometers, our microfluidic system employs samples of less than 30 µl to complete a measurement. Viscosity coefficients of ethanol and fetal bovine serum, as typical examples of Newtonian and non-Newtonian fluids, were obtained experimentally, and found to be in excellent agreement with theoretical predictions. Additionally, a practical application to a DNA solution with incremental ethidium bromide content was employed and the results are consistent with clinical data, indicating that our system provides a potentially important complementary tool for use in such biological and medical applications.
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.
Fabrication and Testing of Viscosity Measuring Instrument (Viscometer
This paper presents the fabrication and testing of a simple and portable viscometer for the measurement of bulk viscosity of different Newtonian fluids. It is aimed at making available the instrument in local markets and consequently reducing or eliminating the prohibitive cost of importation. The method employed is the use of a D.C motor to rotate a disc having holes for infra-red light to pass through and fall on a photo-diode thus undergoing amplification and this signal being translated on a moving-coil meter as a deflection. The motor speed is kept constant but varies with changes in viscosity of the fluid during stirring, which alter signals being read on the meter. The faster is revolution per minute of the disc, the less the deflection on the meter and vise-versa. From the results of tests conducted on various sample fluids using data on standard Newtonian fluids as reliable guide the efficiency of the viscometer was 76.5%.
An optical capillary flow viscometer
Review of Scientific Instruments, 1995
Viscosity sensor using ZnO and AlN thin film bulk acoustic resonators with tilted polar c-axis orientations J. Appl. Phys. 110, 094511 (2011) Viscosity measurements of liquids under pressure by using the quartz crystal resonators Rev. Sci. Instrum. 82, 095114 Rod-shaped nanostructures based on superparamagnetic nanocrystals as viscosity sensors in liquid J. Appl. Phys. 110, 064907 High magnetomechanical coupling on magnetic microwire for sensors with biological applications Appl. Phys. Lett. 96, 262512 (2010) Effects of the positioning force of electrostatic levitators on viscosity measurements Rev. Sci. Instrum. 80, 013906 (2009) Additional information on Rev. Sci. Instrum.
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.
Microchannels for applications in liquid dosing and flow-rate measurement
Sensors and Actuators A-physical, 1997
To investigate the performance of microengineered fluid channels in liquid dosing applications, llow-rate mc,'tsurements have been l)erliwmed with various channel geometries in a range from 0.0l to 1000 ixl min-~. An optical flow-measurement technique has been developed to enhance the measurement range into the desired low flow range ( 10-3 to I ~1 rain-t), and is compared to a standard gravimetric method, which is preferably used for flow rates above 1 ~1 min-~. In addition, influences of the temperttture-dependent viscosity and effects arising from fluidmechanical characteristics are studied. These influences are also calculated from laminar llow theory and semi-empMcal models to obtain a theoretical model. It is found that the theoretical model is able to describe the measurement results well in the whole flow range. The model is implemented on a PC-based system, which measures the pressure drop across the microchannel and the fluid temperature and calculates the flow. In a temperature range from 20 to 50°C excellent agreement is l'ound. © 1997 Elsevier Science S.A.
Analytical Chemistry, 2012
The construction and operation of a novel viscometer/rheometer are described. The instrument is designed to measure the viscosity of a macromolecular solution while automatically varying both solute concentration and shear rate. Viscosity is calculated directly from Poiseuille's Law, given the measured difference in pressure between two ends of a capillary tube through which the solution is flowing at a known rate. The instrument requires as little as 0.75 ml of a solution to provide a full profile of viscosity as a function of concentration and shear rate, and can measure viscosities as high as 500 cP and as low as 1 cP, at shear rates between 10 and 2 × 10 3 s-1. The results of control experiments are presented to document the accuracy and precision of measurement at both low and high concentration of synthetic polymers and proteins.
A differential viscosity detector for use in miniaturized chemical separation systems
Journal of Microelectromechanical Systems, 2000
In this paper, we present a micromachined differential viscosity detector suitable for integration into an on-chip hydrodynamic chromatography system. The general design, however, is applicable to any liquid chromatography system that is used for separation of polymers. The micromachined part of the detector consists of a fluidic Wheatstone bridge and a low hydraulic capacitance pressure sensor of which the pressure sensing is based on optical detection of a membrane deflection. The stand-alone sensor shows a resolution in specific viscosity of 3 10 3 , in which specific viscosity is defined as the increase in viscosity by a sample, relative to the baseline viscosity of a solvent.