A continuum model for flow induced by metachronal coordination between beating cilia

In this numerical study we investigate the flow induced by metachronal coordination between beating cilia arranged in a densely packed layer by means of a continuum model. The continuum approach allows us to treat the problem as two-dimensional as well as stationary, in a reference frame moving with the speed of the metachronal wave. The model...

Micro and Nanofluidic devices: For Single cell and DNA analysis

Research in the field of Micro/nanofluidics has been extensively carried out for the last few years. With the available technological advancements today many complex systems can be fabricated in a more efficient and simpler way. Conventional methods in a laboratory consumes a lot of time, chemicals and in turn generates a lot of waste unlike the...

Low voltage electroosmotic pump for high density integration into microfabricated fluidic systems

A low voltage electroosmotic (eo) pump suitable for high density integration into microfabricated fluidic systems has been developed. The high density integration of the eo pump required a small footprint as well as a specific on-chip design to ventilate the electrolyzed gases emerging at the platinum (Pt) electrodes. For this purpose, a novel...

Optofluidic microsystem for on-chip L2-waveguide modulation featuring flow stabilization and a novel input coupling region

We present an optofluidic microsystem integrated onto a single device featuring on-chip light guiding and positioning under stable and low-loss conditions. Integration of optical components onto a microfluidic chip offers numerous new possibilities in the field of particle and cell analysis, but reconfigurable on-chip light positioning is still...

Developing and Analysing sub-10 µm Fluidic Systems with Integrated Electrodes for Pumping and Sensing in Nanotechnology Applications

In this thesis, sub-10 µm fluidic systems with integrated electrodes for pumping and sensing in nanotechnology applications were developed and analyzed. This work contributes to the development of the scanning ion pipette (SIP), a tool to investigate surface changes on the nanometer scale induced by locally administering chemically or bio-active...

Miniaturized flow cytometer with 3D hydrodynamic particle focusing and integrated optical elements applying silicon photodiodes

In this study, the design, realization and measurement results of a novel optofluidic system capable of performing absorbance-based flow cytometric analysis is presented. This miniaturized laboratory platform, fabricated using SU-8 on a silicon substrate, comprises integrated polymer-based waveguides for light guiding and a biconcave cylindrical...

Formation and Transport of Bubbles in Microfluidic Systems

Precise manipulation of minute volumes of fluids is at the heart of microfluidics and opens up an exciting route to miniaturize processes in the areas of chemistry, biology and medicine. An attractive way to transport small fluid samples through the channels of microfluidic devices is by enclosing these samples inside containers in the form of...

Bioparticle Separation in Microfluidic Devices for in-Line Application

There was an explosive growth in the bioprocess industry market during the last decade. The tight control of these processes is often very critical in order to optimize the process efficiency or even achieve the right product. Capillary electrophoresis (CE) system is a good option for process monitoring and controlling, since it has already been...

Numerical simulations of rarefied gas flows in thin film processes

Many processes exist in which a thin film is deposited from the gas phase, e.g. Chemical Vapor Deposition (CVD). These processes are operated at ever decreasing reactor operating pressures and with ever decreasing wafer feature dimensions, reaching into the rarefied flow regime. As numerical simulation tools are frequently used to design and...

A Hard Constraint Algorithm to Model Particle Interactions in DNA-laden Micro Flows

We present a new method for particle interactions in polymer models of DNA. The DNA is represented by a bead-rod polymer model. The main objective in this work is to implement short range forces to properly model polymer-polymer and polymer-surface interactions. We will discuss two methods for these interactions: (1) a new rigid constraint...

Design of micro-fluidic bio-reactors

We address the design of optimal reactors for supporting biological cultures using the method of topology optimization. For some years this method have been used to design various optimal microfluidic devices [1, 2, 3, 4]. We apply this method to distribute optimally biologic cultures within a flow of nutrition. From this optimized distribution...

Computing the near-wall region in gas micro- and nanofluidics: Critical Knudsen layer phenomena

In order to capture critical near-wall phenomena in gas micro- and nanoflows within conventional CFD codes, we present scaled Navier-Stokes-Fourier (NSF) constitutive relations. Our scaling is mathematically equivalent to applying an 'effective' viscosity to the original constitutive relations. An expression for this 'effective' transport...

Droplets in microchannels with Level Set method

The field of microfluidics has dramatically improved over the last decade: it enables the transport of minuscule amounts of fluid (nanolitres) through channels the diameter of a single human hair. This miniaturization is increasingly employed to build a wide range of technological devices for example, genome sequencing or using microdroplets as...

Development of a miniaturized total chemical analysis system for real-time monitoring of fermentations

Dynamics of droplet formation at T-shaped nozzles with elastic feed lines

We describe the formation of water in oil droplets, which are commonly used in lab-on-a-chip systems for sample generation and dosing, at microfluidic Tshaped nozzles from elastic feed lines. A narrow nozzle forms a barrier for a liquid–liquid interface, such that pressure can build up behind the nozzle up to a critical pressure. Above this...