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Acoustic Monitoring and Characterization of Drug Tablets
Physical properties and mechanical integrity of drug tablets as well as their coat thickness and quality can affect their critical therapeutic and structural functions. Monitoring for defects and the characterization of tablet mechanical properties are of great practical interest in drug tablet manufacturing and unit operations, as noted in FDA's PAT and QbD initiatives. The objective of this project is to develop non-invasive, non-destructive acoustic techniques for pharmaceutical manufacturing applications as well as to understand fundamental factors affecting mechanical properties of tablets.

Real-Time Acoustic Monitoring of Drug Tablet Compaction
Compaction represents one of the most essential unit operations in the pharmaceutical manufacturing industry because physical and mechanical properties of the tablets, such as density and strength (hardness/friability) as well as the functional characteristics (e.g. dissolution rate) are determined during this process. The objective of this project is to develop real-time acoustic techniques for monitoring compaction in dies. In the Photo-Acoustics Research Laboratory, we utilize an instrumented die-punch setup and  to simulate the compaction process, to extract elastic properties of drug tablet cores as well as to monitor the die-wall lubrication and die-fill height during pharmaceutical compaction process using acoustic methods.

Transport and Manipulations of Micro-Particles on Dry Surfaces
Gaining fundamental understanding of the transport and motion of small-scale objects on dry surfaces is the focus of this research effort. The needs in this area have been growing, as more micro/nano-technology applications require the transport and manipulations in nano/micro-scale. Our research efforts in this area focus on the transport and motion characteristic of micro-spheres under the influence of acoustic fields generated in solid substrates and in air by piezoelectric transducers.

MEMS Rotational Disk Oscillators for High-Frequency Sensors
A free-standing rotational oscillator has been developed as a novel detection element in mass sensing in liquid and air media. Traditional oscillators, such as cantilever beams, operate in out-of-plane vibrational modes, which limit the operation frequencies, and result in excessive stresses and high damping (low Q factor) in the device leading to reduced measurement sensitivities. High damping associated with out-of-plane motion is particularly dominant in liquids. Rotational oscillators would drastically decrease damping and stress in liquid phase by providing a rotational mode. Our main research objective is to gain fundamental understanding in vibrational motion of such disks and their uses in practical sensing applications.

Effect of Residual Stress on Structure Stability of Microscale Membranes
During fabrication, large deformations are observed in very high-aspect ratio free-standing micro-scale membranes. Axi-symmetric and full three dimensional membrane models of a 1.6 μm thick, 6 mm diameter membrane were developed to study the structural stability of these membranes with substantial residual stresses.

MD Simulations of Nanoparticle-Substrate Adhesion
A Molecular Dynamics (MD) simulation study is initiated to gain fundamental understanding of rolling and sliding elasto-adhesion interactions between a spherical nanoparticle and a substrate. This study is needed to understand the modes of particle removal and detachment for cleaning of semiconductor substrates, MEMS, the strength and stability of network of adhered round objects in a diverse spectrum of applications (e.g. particles, powders, blood cells and nanotubes) on micro/nano-scale.

Shock Tube Pressure Amplification for LIP Nanoparticle Removal
Nanoscale substrate cleanliness is a critical requirement in nanotechnology and semiconductor applications. A novel particle removal technique based on Laser Induced Plasma (LIP) shockwaves has been introduced and evaluated for nanoparticle removal by the Photo-Acoustics Research Laboratory. An in-air and submerged method using shock tubes for amplifying the dynamic pressure of LIP shockwaves for removing sub-50 nmnanoparticles has been demonstrated.

Substrate Damage in Nanoparticle Removal under LIP Exposure
Damage-free sub-100nm particle removal is a challenge in the semiconductor industry and nanotechnology. Laser induced plasma (LIP) is an emerging technique for fast, dry, chemical-free, non-contact, precision and selective cleaning of sub-100 nm particles. Determination of the primary causes for material alterations and damage due to LIP application in nanofilms deposited on substrates utilized in EUVL/photomasks, as well as investigation of the onset of these material alterations were the objectives of this investigation.