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Microfluidic filtration is an essential process in many biomedical applications. Micro or nanoporous membranes are used for colloidal retention. During the membrane filtration process visualization of various phenomena is challenging. Theoretical models have been proposed to visualize the transport mechanism. In this work, ANSYS Fluent is used for 3D designing of the microfluidic system and Fuzzy simulations are used to study flow rate and velocity, to get the maximum benefit from Anodized Aluminium oxide membrane in practical applications. The proposed method exploits relations between driving force, membrane area, and fluid flow. After optimization of parameters for the filtration, the AAO membrane with desired pore diameter was fabricated using the two-step anodization method. Scanning electron microscope is used for characterization of fabricated AAO membrane. The simulated and theoretical results using computer-based programs are then compared for manipulation of flow rate during the filtration process. Along with the manipulation of flow rate from nanoporous membrane other challenges faced during the filtration process are also highlighted with possible solutions. [ABSTRACT FROM AUTHOR]

Bioengineered veins can benefit humans needing bypass surgery, dialysis, and now, in the treatment of varicose veins. The implant of this vein in varicose veins has significant advantages over the conventional treatment methods. Deep vein thrombosis (DVT), vein patch repair, pulmonary embolus, and tissue-damaging problems can be solved with this implant. Here, the authors have proposed biomedical microdevices as an alternative for varicose veins. MATLAB and ANSYS Fluent have been used for simulations of blood flow for bioengineered veins. The silver based microchannel has been fabricated by using a micromachining process. The dimensions of the silver substrates are 51 mm, 25 mm, and 1.1 mm, in length, width, and depth respectively. The dimensions of microchannels grooved in the substrates are 0.9 mm in width and depth. The boundary conditions for pressure and velocity were considered, from 1.0 kPa to 1.50 kPa, and 0.02 m/s to 0.07 m/s, respectively. These are the actual values of pressure and velocity in varicose veins. The flow rate of 5.843 (0.1 nL/s) and velocity of 5.843 cm/s were determined at Reynolds number 164.88 in experimental testing. The graphs and results from simulations and experiments are in close agreement. These microchannels can be inserted into varicose veins as a replacement to maintain the excellent blood flow in human legs. [ABSTRACT FROM AUTHOR]

This paper deals with the design of a new hemofiltration system that consists of a blood transport device, a blood filtration device, a drug delivery device, flow sensors, blood pressure sensors, and the required control electronic circuits. The simulation and fabrication of microneedles and hemofilter have been performed. Silicon microneedles with length (L) =\ 200\ \mum, internal diameter (Di) =\ 60\ \mum, and outer diameter (Do) =\ 150\ \mum have been successfully fabricated using inductive coupled plasma (ICP) etching technology for drug delivery. An aluminum (Al)-based hemofilter with hexagonal pores has been fabricated for blood filtration. Strength modeling and microfluidic analyses of the hemofilter have been conducted in finite element software to envisage structural properties and to model blood flow through the hexagonal pores. Simulation results show that a flow rate of 488.43 \muL/min has been obtained at a driving pressure of 250 kPa through a hemofilter with hexagonal pores. Transient multifield analysis of the blood transport device (double lumen, side open, reservoir-based microneedles integrated with a piezoelectric actuator) has been conducted using the finite element method. The effects of actuator thickness, applied frequency and voltage on fluid flow rate have been investigated using the blood transport device. A maximum flow rate of 475 \muL/min has been observed through 25 microneedles at an applied voltage of 125 V with a frequency of 250 Hz. [ABSTRACT FROM PUBLISHER]

Micro Electromechanical Systems (MEMS) based microfluidic devices have gained popularity in biomedicine field over the last few years. In this paper, a comprehensive overview of microfluidic devices such as micropumps and microneedles has been presented for biomedical applications. The aim of this paper is to present the major features and issues related to micropumps and microneedles, e.g., working principles, actuation methods, fabrication techniques, construction, performance parameters, failure analysis, testing, safety issues, applications, commercialization issues and future prospects. Based on the actuation mechanisms, the micropumps are classified into two main types, i.e., mechanical and non-mechanical micropumps. Microneedles can be categorized according to their structure, fabrication process, material, overall shape, tip shape, size, array density and application. The presented literature review on micropumps and microneedles will provide comprehensive information for researchers working on design and development of microfluidic devices for biomedical applications. [ABSTRACT FROM AUTHOR]