Chandraprakash Chindam

Fourier Modal Method and Its Applications in Computational Nanophotonics

Hwi Kim, Junghyun Park, and Byoungho Lee, 2012, ISBN-10: 1420088386, ISBN-13: 9781420088380, xii+313 pages, CRC Press, Boca Raton,

Exploring bubble oscillation and mass transfer enhancement in acoustic-assisted liquid-liquid extraction with a microfluidic device.

179.95 hardcover,

Parylene-C microfibrous thin films as phononic crystals

125 e-book. LCCN: 2011046920, OCLC:768728882 Reviewed by Chandraprakash Chindam, Pennsylvania State University, Department of Engineering Science and Mechanics, University Park, Pennsylvania 16802, USA

Acoustic scattering from microfibers of Parylene C

We investigated bubble oscillation and its induced enhancement of mass transfer in a liquid-liquid extraction process with an acoustically-driven, bubble-based microfluidic device. The oscillation of individually trapped bubbles, of known sizes, in microchannels was studied at both a fixed frequency, and over a range of frequencies. Resonant frequencies were analytically identified and were found to be in agreement with the experimental observations. The acoustic streaming induced by the bubble oscillation was identified as the cause of this enhanced extraction. Experiments extracting Rhodanmine B from an aqueous phase (DI water) to an organic phase (1-octanol) were performed to determine the relationship between extraction efficiency and applied acoustic power. The enhanced efficiency in mass transport via these acoustic-energy-assisted processes was confirmed by comparisons against a pure diffusion-based process.

Relative permittivity of bulk Parylene-C polymer in the infrared regime

Phononic bandgaps of Parylene-C microfibrous thin films (muFTFs) were computationally determined by treating them as phononic crystals comprising identical microfibers arranged either on a square or a hexagonal lattice. The microfibers could be columnar,chevronic, or helical in shape, and the host medium could be either water or air. All bandgaps were observed to lie in the 0.01-to-162.9-MHz regime, for microfibers of realistically chosen dimensions. The upper limit of the frequency of bandgaps was the highest for the columnar muFTF and the lowest for the chiral muFTF. More bandgaps exist when the host medium is water than air. Complete bandgaps were observed for the columnar muFTF with microfibers arranged on a hexagonal lattice in air, the chevronic muFTF with microfibers arranged on a square lattice in water, and the chiral muFTF with microfibers arranged on a hexagonal lattice in either air or water. The softness of the Parylene-C muFTFs makes them mechanically tunable, and their bandgaps can be exploited in multiband ultrasonic filters.

Theory and experiment on resonant frequencies of liquid-air interfaces trapped in microfluidic devices

The acoustic scattering characteristics of ∼10 μm-long microfibers of Parylene C embedded in water were investigated, towards the eventual goal of designing polymeric sculptured thin films for biomedical applications. The chosen microfibers were upright circular-cylindrical, slanted circular-cylindrical, chevronic, and helical in shape. A combination of numerical and analytical techniques was adopted to examine the scattering of plane waves in a spectral regime spanning the lower few eigenfrequencies of the microfibers. Certain maximums in the spectrums of the forward and back scattering efficiencies arise from the phenomenon of creeping waves. The same phenomenon affects the total scattering efficiency in some instances. The spectrums of all efficiencies exhibit the geometric symmetry of a microfiber in relation to the direction of propagation of the incident plane wave. Similarities in the shapes of the slanted circular-cylindrical and the chevronic microfibers are reflected in the spectrums of their sc...

Microfiber inclination, crystallinity, and water wettability of microfibrous thin-film substrates of Parylene C in relation to the direction of the monomer vapor during fabrication

Infrared spectroscopy experiments in the 15–149 THz spectral regime were performed in the transmission mode on a thin film of bulk Parylene-C polymer at normal incidence. The relative permittivity of bulk Parylene-C polymer in this regime was modeled as comprising a frequency-independent term as well as contributions from 32 Lorentz oscillators. A least-squares minimization algorithm and a hybrid genetic algorithm were used to determine the frequency-independent term as well as all parameters characterizing the Lorentz oscillators from the measured transmittance spectrum itself.