Study of blood flow behaviour in microchannels (original) (raw)
Related papers
Computational and Functional Evaluation of a Microfluidic Blood Flow Device
ASAIO Journal, 2007
The development of microfluidic devices supporting physiological blood flow has the potential to yield biomedical technologies emulating human organ function. However, advances in this area have been constrained by the fact that artificial microchannels constructed for such devices need to achieve maximum chemical diffusion as well as hemocompatibility. To address this issue, we designed an elastomeric microfluidic flow device composed of poly (dimethylsiloxane) to emulate the geometry and flow properties of the pulmonary microcirculation. Our chip design is characterized by high aspect ratio (width > height) channels in an orthogonally interconnected configuration. Finite element simulations of blood flow through the network design chip demonstrated that the apparent pressure drop varied in a linear manner with flow rate. For simulated flow rates <250 l min ؊1 , the simulated pressure drop was <2000 Pa, the flow was laminar, and hemolysis was minimal. Hemolysis rate, assayed in terms of [total plasma hemoglobin (TPH) (sample ؊ control)/(TPH control)] during 6 and 12 hour perfusions at 250 l/min, was <5.0% through the entire period of device perfusion. There was no evidence of microscopic thrombus at any channel segment or junction under these perfusion conditions. We conclude that a microfluidic blood flow device possessing asymmetric and interconnected microchannels exhibits uniform flow properties and preliminary hemocompatibility. Such technology should foster the development of miniature oxygenators and similar biomedical devices requiring both a microscale reaction volume and physiological blood flow. ASAIO Journal 2007; 53:447-455.
APPLICATIONS OF MICROFLUIDIC SYSTEMS IN BIOMEDICAL ENGINEERING
INTRODUCTION Microfluidics is the science and technology of systems that process or manipulate small (10–9 to 10–18 litres) amounts of fluids, using channels with dimensions of tens to hundreds of micrometres. Its first Application is in analysis, in which it offer a number of useful capabilities which include the ability to use very small quantities of samples and reagents, and to carry out separations and detections with high resolution and sensitivity. Using Microfluidics in this Application greatly reduced cost and time of analysis. Microfluidics is a compound word, Micro meaning small size and fluidic, gotten from fluid (Liquid or Gas) thus to a layman, Microfluidics is the playing around with small Liquids or gases. Microfluidics offers fundamentally new capabilities in the control of concentrations of molecules in space and time. As a technology, Microfluidics seems almost too good to be true: it offers so many advantages and so few disadvantages. But it has not yet become widely used. Microfluidics systems are devices in which low volumes of fluids are processed to achieve multiplexing, automation, and high-throughput screening. Such Devices emerged in the early 80s and have been used in the development of inkjet printheads, DNA chips, lab-on-a-chip technology, micro-propulsion, and micro-thermal technologies. It deals with the behavior, precise control and manipulation of fluids that are geometrically constrained to a small, typically sub-millimeter scale. Microfluidics systems typically comprises of active (micro) components such as micro pumps and micro valves. Micro pumps supply fluids in a continuous manner and can be used for dosing. Micro valves determine the flow direction or the mode of movement of pumped liquids. Often processes which are normally carried out in a lab are miniaturized on a single chip in order to enhance efficiency and mobility as well as reducing sample and reagent volumes. Microfluidics Systems have a broad range of Application but in this Pepar, we will concentrate on its Applications in Biomedical Engineering.
Characterization of microfluidic components for low-cost point-of-care devices
This paper presents the characterization of microfluidic components for the realization of low-cost point-of-care diagnostic devices, with focus on full blood count applications. We present a set-up to enable automated actuation of device components utilizing parameters similar to those produced by manual actuation. Initial results show that simple microfluidic components can be used to achieve repeatable and accurate results for sample and reagent introduction and propulsion, as well as mixing and dispersion of sample and reagent, without the need for complex microfluidic operations.
Continuous Flow Pressure Driven Microfluidic Techniques for Point of Care Testing
The recent advent of the miniaturization technology witnessed over the last decades has led to development and creation of several conventional microfluidic techniques. A microfluidic platform can be broken down into a set of fluidic unit operations which are miniaturized versions of orthodox large scale (biochemical) laboratory operations. These miniaturized operations are designed for easy integration and automation within a well-defined fabrication technology; which permits simple, easy, fast, and cost-efficient implementation of different application-specific biochemical processes for point care diagnostics. Processes that can be automated at this scale include nucleic acid extraction, amplification and detection. The improvement in technology within the previous decades has led to significant developments of techniques used in implementing several microfluidic processes. The auspicious developments that have greatly impacted areas in medical research, therapeutics and POCT applications are brought into focus by this research on a continuous flow configuration. Through these visualization platforms such as pressure driven flow, magnetohydrodynamics dielectrophoresis, large-scale integration are analyzed under continuous flow characteristics. Finally this review also provides adequate examples whilst investigating the strengths and limitations of every technique.
Procedia Engineering, 2016
Microfluidic devices exploit combined physical, chemical and biological phenomena that could be unique in the sub-millimeter dimensions. The blood is a non-Newtonian fluid, containing particulate and soluble elements, which penetrates the whole body carrying a wealth of biomedical information. The design of microfluidic devices capable of extracting immediately this information is the current goal of development Point-of-Care (POC) medical devices. We examined the characteristics of blood flow in specially designed microfluidic devices having different geometric structure and material composition with the aim of defining suitable conditions for sensitive detection of changes in the interactions between particulate elements of the blood and the adequately modified surfaces of the microfluidic system. As a model experiment we demonstrated the fast analysis of the AB0 blood group system, applying respective antibody reagents and capillary blood samples with different blood groups. We showed that by tuning the hydrophilicity of the surface and capillary dimensions of the microfluidic system it is possible to detect precisely the red blood cell binding to the capillary walls by monitoring the flow rate characteristics in an autonomous microfluidic system. Our proof-of-concept results point to a novel direction in blood analysis in autonomous microfluidic systems and also provide the basis for the construction of a simple quantitative device for blood group determination.
Reference Module in Chemistry, Molecular Sciences and Chemical Engineering, 2013
Microfluidics concerns the manipulation of small volumes of fluids (typically nanoliters or less) within networks of channels that have dimensions of tens to hundreds of micrometers. Such devices benefit from having small footprints, low volume requirements of samples and reagents, short analysis times, and a large degree of control over processes being performed, allowing miniaturization of single or multiple laboratory-based procedures and giving rise to ‘lab-on-a-chip’ technology. Microfluidic platforms have become powerful tools in a broad range of fields, from chemistry and engineering to the life sciences, and are revolutionizing the way research can be performed and the quality of information that can be gained.
Flow of Physiological Fluids in Microchannels: The Sedimentation Effect
Microfluidic devices are becoming one of the most promising new tools for diagnostic applications and treatment of several chronic diseases. Hence, it is increasingly important to investigate the rheological behaviour of physiological fluids in microchannels. The main purpose of the present experimental work is to investigate the flow of two different physiological fluids frequently used in microfluidic devices. The working fluids were physiological saline (PS) and dextran 40 (Dx40) containing about 6% of sheep red blood cells (RBCs), respectively. The capillaries were placed horizontally on a slide glass and the flow rate of the working fluids was kept constant by using a syringe pump. By means of a camera the images were taken and transferred to the computer to be analysed. Generally, the results show that PS and Dx40 have different flow behaviour due to the sedimentation of the RBCs.