Control of drop motion by means of optical patterns imprinted on Fe:LiNbO3 crystals
Chemical and morphological surface patterning is very common in microfluidic devices to control the flow. In this project, the student will study the dynamics of water droplets moving on a Fe:LiNbO3 crystal which has been exposed to optical patterns produced by a spatial light modulator. In particular, periodic stripes of different intensity and width will be analyzed. In order to reduce the surface pinning, the crystal will be covered with a lubricant infused surface.
The motion of drops on these tilted, functionalized surfaces will be analyzed by means of video cameras at high resolution. The resulting dynamics will be obtained by processing these videos offline with custom made programs.
Development and validation of droplet microfluidics device for biological applications
A key element for biological applications is the compartmentalization that allows obtaining independent and large data sets. Typically, this is achieved by distributing different solutions in independent wells of a microtiter plate. An improvement of this compartmentalization can be achieved through the droplet microfluidics. Here, controlled emulsion of droplets of one liquid phase dispersed in another liquid is produced in microfluidic channels at very high rate (>1kHz). For biological applications, the emulsions are composed by aqueous-phase droplets dispersed in oil mixed with specific surfactants. In this way, each droplet is considered as a single reactor, which guarantees stable separation of chemicals, bio-molecules and even cells, as well as reducing the volume of the involved liquids and the contamination risks with the surroundings environment.
In this project we aim to develop a droplet microfluidic device devoted to liquid biopsy for cancer diagnosis: body fluids (e.g.: blood) are screened looking for specific biomarkers, which are released from cancer cells and can give information on the tumor. Therefore, the student will acquire knowledge in microfluidics and microscopy, as well as, on molecular and cell biology, in collaboration with the department of molecular medicine. This study is developed in the context of EXODROP, a project founded by the STARS grant of the University of Padova.
Study of droplet generation and transport in microfluidic channels
Microfluidics is the science and technology for manipulating small amounts of fluids (pL and nL ranges), through channels of tens to hundreds microns size. During the past 20 years, microfluidics raised the concept of Lab-on-a-Chip, consisting in the integration of chemical and biological assays in small devices. Nowadays, a specific branch of microfluidics, known as droplet microfluidics, is currently experiencing a great impact in many biological applications. Here, two immiscible fluids are put into contact by specific geometrical microfluidic channel junctions, to produce controlled emulsion of droplets of one phase dispersed in the other. Despite their diffusion, droplets transport in microfluidic channels is not completely understood; in fact, their shape and speed may vary by several factors, e.g. viscosity, surface tension, geometry, etc.
In this project, the student will study how this factors influence both droplet generation and transport. Therefore, the student will acquire knowledge in microfabrication in clean room laboratory, microfluidics and soft-matter.
Single-molecule experiments with optical tweezers
Optical Tweezers are a powerful tool to investigate the microscopic world and the recent achievements in nanotechnology and material science have significantly enhanced the potentialities offered by this technique. Among the others, the possibility to manipulate biological systems at the single-molecule level is surely one of the most amazing, which allows to provide a complementary and different perspective with respect to traditional ensemble-based methods. Thanks to their capability to control forces and movements with unprecedented resolution (pN and nm), Optical Tweezers are especially suitable to manipulate individual DNA/RNA molecules and proteins, allowing to investigate aspects of molecular thermodynamics and kinetics that are sometimes difficult to be obtained via bulk experiments. The student will investigate the elastic response of a biological system (ssDNA-based biosensors or proteins) by means of force spectroscopy experiments performed on single molecules, to determine the main biophysical parameters which regulate their folding and unfolding mechanisms.
The student will be actively involved both in the experiments and data analysis and she/he will acquire knowledge in optics and optical tweezing, as well as biophysics and molecular biology.
Soft Glassy Materials flow and plastic rearrangements in microfluidic channels
Soft Glassy Materials (SGM) include dense emulsion, foams and gels, which show a peculiar non-Newtonian rheology. In detail, they typically behave like a solid unless a large stress is applied; above this stress, they flow like a liquid. It has been recently demonstrated that when they flow in microchannels, this transition can be induced by the presence of a roughness on the channel’s walls. Since their control at the microscale is pivotal for many applications ranging from pharmaceutical to food technology, the scope of this study is to investigate this transition in different experimental condition.
The student will study and characterize the flow of non-Newtonian fluids in microfluidic channels patterned with different types of microstructures, acquiring competences in their preparation, flow control and microscopy.
Scheme of the flow in the microchannel