UG Courses Taken (Shared)

Instabilities at Soft Interfaces

Study of pattern formation in Ferrofluids: Ordered patterns of ferrofluids formed through self-organization in the nanometer scale having very high aspect ratios will have huge technological applications as actuators in MEMS/NEMS, in fabrication of thin film solar cells, in creation of optical diffraction gratings and so on. Moreover, since the magnetic field is an external field, it can be altered externally and a pulsating motion can be set in at such small scale, utilizable in creating artificial organs like heart. The convective flow generation can be utilized in microfluidic devices to generate turbulence and moreover, the planar self-organization of magnetic nano-particles when cast as a bilayer over a polymeric fluid in the presence of a perpendicular electric field, can be harnessed to create high-end sensors. Fabrication of PS-PDMS-graphene blends: With the advancement in the field of polymer and nanoparticles and their huge application; the prospect of designing new polymers incorporated with nanoparticles has large technological importance. The aim of the research is to design an immiscible blend of an elastomer polydimethyl siloxane (PDMS) and thermoplastic polystyrene (PS) and incorporate it with graphene and carbon nanotube nanoparticles. The compatibility in case of immiscible polymer blend remains a challenge for both scientific and technological purposes. The goal of the project is to apprehend the development in the field of immiscible blend, creating thin film and also to understand the variance when the nanoparticles are part of the blend. The dependence of the blend morphology on different factors such as blend composition, thickness of the film, temperature, substrate morphology, and application of shear rate is expected to develop interesting structures. The arrangement of the nanoparticle in the PDMS/PS blend has to be probed in the phase separated blend and also in continuous domain of the blend. The immiscible blend film created will possibly generate mesoscale patterns with varying length scale. The change in conductivity with addition of carbon nanoparticles need to be investigated. The hydrophobicity and hydrophilicity, along with the adsorption of oil over the patterns created with nanoparticles embedded in immiscible polymer blend may be an interesting scope of study for its application. The topic of this work finds application in the field of nanotechnology; is of considerable interest to the polymer blend and carbon nanoparticles domain and mostly to the phase separation community.

Nano-Particle Self-Assembly at Soft Interfaces

The grapheme and CNT nanoparticles self-assemble during dewetting over PS to give very nice surface patterns These patterned surfaces are biocompatible and have high potential to be used for

• Sensors for gas sensing
• As bio-electrodes for fuel cells
• As advanced surfaces for CO₂ adsorption and storage
• As surfaces for tissue engineering
• For cancer detection etc.

So the applicative side of the work that has already been done will be pursured. Along these lines the following will be done also: Bacteria assisted 3D CNT/Graphene Sponge for CO₂ adsorption: So in the present project the aim will be to create a porous 3D structure of both CNT and graphene so that the surface area for adsorption made available is manifold than presently available. This can be achieved by dispersing the nanoparticles in a colony of bacteria. The growth dynamics and the diffusion of bacteria will lead to unique self-assembled 3D porous structures of colonies. The suspended nanoparticles under concern are anticipated to take the underlying structure of the colonies; also they can self-assemble on their own. Exposing the culture to CO₂ or high temperature can kill the bacterial cells and the resulting 3D porous structure of the nanoparticles can be subsequently used for the gaseous absorption. The structures can also be thermally treated or chemically modified during the course for enhancing adsorption. Fabrication of a Multifunctional polymer composite having Thermo-Piezo-Conductivity for Energy Harvesting: The present proposal is aimed to develop a smart multi-functional polymer composite, that will respond to thermal stimuli (which is easier to control than a mechanical one) and that too around room temperature or human body temperature and can produce electricity directly and thus, can be used for energy harvesting. For this purpose, in the present project, a polymer composite will be made out of three polymers viz, a thermo-responsive, a piezoelectric and a conductive one, where each of the layer, spin coated on the top of the other will respond to the stimuli of the preceding one. How thermal response will be converted into a mechanical one will be studied numerically and experimentally with the help of AFM, and how this mechanical stimulus is converted into electric charges in the piezo-layer will be measured with the help of an oscilloscope. The conductive layer at the top will help the charges accumulated in the piezo layer to flow. The conductivity displayed by the top-polymer layer and hence the current produced will be investigated by a 4-point conductive meter and from an impedance study. Whether introducing biocompatible nanoparticles like graphene can enhance the performance of such a composite will be studied further. It is anticipated that smaller the thicknesses of each of the layer better will be the stimuli transitivity. For this purpose not only discrete polymer layers will be tested but layer by layer deposition of the three different polymers by dip-coating as well as electro spinning of the polymer matrix into fibers will be done. The comparative efficiencies will be analyzed to obtain the optimized processing conditions. The results found here will help in fundamental understanding of the unique functionality of each of the polymer layer and their smart interactions with each other. The present project will help in fabricating future experiments in the field of energy harvesting in its quest for cleaner source of electricity and in developing new biocompatible sensors and actuators.

Complex Fluid Rheology

From outer space to natural phenomena like avalanches, from raw materials of chemical industries to daily house hold items like rice, sugar, salt: presence of granular materials are ubiquitous in nature. Granular materials fall under the category of complex fluids because of the diverse and complex rheology they display depending upon the amount of moisture content in their matrix. Rheology of wet granulates are even more poorly understood. In simple static packed beds, because of lower process characteristic time compared to fluid relaxation time (high Deborah number), even fluids like water exhibit strong elastic behavior. Thus, wet granulates as found in mineral extraction via froth floatation, in waste water treatment etc. are anticipated to exhibit viscoelastic rheology, understanding of which is essential for an optimal process operation. In the present project through LBM simulations it is intended to find the viscoelastic properties of such wet granulates under oscillatory shear. Moreover for binary fluid it has been seen that oscillatory shear leads to phase separation. It will be interesting to see whether for the poly-dispersed wet granulate system; oscillatory shear can lead to such size separation.

Design of Equipments through CFD

Ventilator design: A design to accommodate multiple patients on a single ventilator with minimalistic and easy design changes which can be applied universally to all makes and builts of ventilators. The design solution involves using readily available plastic tubing to split up the oxygen supply from a single ventilator among multiple patients (the number could be as high as 8 or 10) instead of being used for a single patient. Using the techniques of Computational Fluid Dynamics (CFD) the design of the split-up system needs to be optimised for it to be fit to use. Also, CFD calculations will give a precise map of insights on how much capacity amplification can be done in different scenarios without causing risk of life. CFD based scale-up study of bioreactor design from lab to industry to maximise yeast biomass production: Yeast-biomass is crucial for bio-ethanol generation: the most promising alternate-energy resource. Through CFD-studies the aim is to optimize different bioreactor-designs for specified reactor-volume and predict ideal operating conditions at different scales conducive in supplying necessary oxygen through mixing, to help sustain aerobic-respiration to maximize yeast growth without allowing cell-lysis.