e-mail Hemang
Research Interests
First an update: I successfully defended my PhD Thesis on August 10, 2007. The dissertation has been submitted at the Drexel University's Haggerty Library and I should officially graduate on September 7, 2007.
My research has focused on development of electro-optic devices by studying the surface interactions of liquid crystals. Devices and applications have always motivated me. In my PhD work, I have developed liquid crystal displays (LCDs), optical data storage devices, studied fluid transport/storage at sub-micrometer scale and developed inkjet printing techniques for carbon nanotubes and ferroelectric polymers.
My projects include:
1.Optical Memory Elements and Analog Liquid Crystal Displays (LCDs) using
ferroelectric polymers and liquid crystals
2. Liquid Crystals inside Carbon Nanotubes
3. Computational modeling of liquid crystal alignment
Ferroelectric polymers and liquid crystals
We are investigating PVDF (polyvinylidene fluoride) for it's ferroelectric
properties. A ferroelectric polymer can store charge, which can be used
to align liquid crystals. The charge can be manipulated using techniques
including corona discharge and electric poling. Thus, a polymer region
exposed to corona discharge will lock the liquid crystal state due to
induced dipoles i.e. there is a memory effect.
Using this idea, we have developed two devices:
1. An optical memory element, which can store information in color saving
space, and processing time
2. A voltage-dependent color display i.e. a LCD which can transmit different
colors based on the applied voltage
Liquid Crystals inside Carbon Nanotubes
The goal of this project is to study the effects of confinement on liquid
crystals and the storage and transport of complex fluids through carbon
nanotubes. We have been able to align the tubes using the liquid crystals,
rotate them in and out-of-plane using electric fields, and image the liquid
crystal wetting inside the tubes using a scanning electron microscope
(SEM).
Computational modeling of liquid crystals
The goal of this project is to model liquid crystal alignment on patterned
substrates. Our codes use the finite-difference method using the simulated
annealing algorithm. The codes minimize the Frank's equation of energy
associated with liquid crystal molecules. However, we are simulating director
i.e. a cluster of molecules as opposed to a molecular-scale simulation.
The code can identify positve and negative defects, defect annihilation,
and real-time visualization of system as it approaches equilibrium.