Robert D. Geil

Rapidly–Dissolvable Microneedle Patches Via a Highly Scalable and Reproducible Soft Lithography Approach

Microneedle devices for transdermal drug delivery have recently become an attractive method to overcome the diffusion-limiting epidermis and effectively transport therapeutics to the body. Here, we demonstrate the fabrication of highly reproducible and completely dissolvable polymer microneedles on flexible water-soluble substrates. These biocompatible microneedles (made by using a soft lithography process known as PRINT) showed efficacy in piercing both murine and human skin samples and delivering a fluorescent drug surrogate to the tissue.

High-temperature tantalum tungsten alloy photonic crystals: Stability, optical properties, and fabrication

We demonstrate tantalum-tungsten (Ta-W) solid solution alloy photonic crystals (PhCs) as spectrally selective components for high temperature energy conversion. The thermo-mechanical properties of the alloy are tuned by the Ta-W ratio. A 2D PhC was designed as a selective emitter, fabricated on a Ta3%W substrate, and optical properties and thermal stability were characterized. A thin layer of HfO2 was deposited for thermal stability. The PhCs show outstanding emittance selectivity, well preserved after annealing for 24h at 1200 °C. The structure is preserved as shown in cross-sectional images, demonstrating that the coating effectively prevents degradation due to surface diffusion at high temperatures.

Penetration of Tagged Organics into Caulked and Un-caulked Porous Dielectrics Measured by Rutherford Backscattering

A novel method for studying the penetration of wet chemicals into caulked and uncaulked porous dielectrics was developed, and the barrier properties of parylene X were evaluated. Rutherford backscattering spectrometry (RBS) was used to study the penetration of chlorine-tagged organics, 3-chloro-1-propanol and a %5 HCl solution. After one minute of exposure time, eight times more 3-chloro-1-propanol diffused through uncaulked porous dielectric compared to caulked porous dielectric. Penetration from the side of the samples was found to be insignificant.

Optimization of UHV-CVD Thin Films for Gate Dielectric Applications

In-situ and ex-situ spectroscopic ellipsometry (SE), atomic force microscopy (AFM), transmission electron microscopy (TEM), and time of flight medium energy backscattering (ToF MEBS), are used to investigate the properties of 30 and 60 Å ZrO2 films deposited at different temperatures on hydrogen terminated silicon (H-Si) and native silicon oxide surfaces. Results show that the initial-stage deposition of ZrO2 on H-Si and native silicon oxide surfaces are different. A 3-dimesional (3D) type nucleation process of ZrO2 on H-Si leads to high surface roughness films, while layer-by-layer deposition on native silicon oxide surfaces leads to smooth, uniform ZrO2 films. An interfacial layer, between the substrate and the metal oxide, is formed through two independent mechanisms: reaction between the starting surfaces and ZTB or its decomposition intermediates, and diffusion of reactive oxidants through the forming ZrO2 interfacial stack layer to react with the substrate.