Photoresist droplets are ejected onto a wafer surface by an acoustic two dimensional micromachined ejector array. The spread of single droplets on a silicon wafer surface at varying droplet speeds is studied. Series of photoresist droplets are printed periodically drop-on-demand on a silicon wafer surface and profiles of a single droplet and two droplets overlapping with varying distances of 25 μm and 1 μm on a silicon wafer are demonstrated. Moreover, 3.4 μm thick spinless full coverage of a 4 inch wafer with photoresist is demonstrated which indicates a potential for coating wafers in less than a few seconds.

Diamond like carbon (DLC) films are synthesized on various substrates using a pulsed KrF excimer laser ablation deposition technique. Variations of laser power density, substrate temperature, angle and distance between the substrate and target yield different sizes of porous surfaces of DLC films. Microscope is used to examine the surfaces. Raman scattering is used to characterize the samples, and the typical G and D bands have been identified. Intensities and profiles of the G and D bands closely depend on laser power density. The relationship between the deposition rate and the power density is also studied.

There is a great need to develop methods to regulate cellular growth in order to enhance or prevent cell proliferation as needed, to either improve health or prevent disease. In this work we evaluated the adhesion, survival and growth of bone marrow stromal cells on the surface of several new ion beam engineered nano-crystals of ceramic hard coatings such as zirconium, titanium, tantalum and cerium oxides. Cell adhesion and growth on the ceramic coatings were compared to adhesion and growth on a nano-crystalline silver coating which is known to possess antibacterial properties. The initial results of a study to determine the effect of nanocrystalline titanium and silver coating on staphylococcus aureus biofilm growth is also discussed.

For bioparticle analysis within microfluidic devices, there is a risk of analytes adhering to surfaces, thereby compromising particle manipulation and recovery. To address this we have implemented polyethylene glycol (PEG)-type coatings by self-assembled monolayer (SAM) and plasma-polymerizing deposition techniques. Silane chemistry is used to deposit SAM films directly onto silicon dioxide surfaces, and in a special case for which a composite of metallic arrays and SiON within our MEMS device must be coated, an ultrathin layer of sputtered Si is added before the SAM protocol. We have also deposited PEG-like tetraglyme by plasma-polymerization onto substrates using an onsite-built reactor to provide antistiction treatment to all surfaces, including those that do not have chemical compatibility for the SAM technique. Three tests demonstrate the effectiveness of our surface treatments: static exposure to microbial suspensions, bioparticle transport across MEMS traveling-wave (TW) arrays, and bioparticle recovery from a circulating flow device. Our static microbial assays show significant reduction in B. thuringiensis adhesion to both the SAM and plasma-polymerized coatings and reduction in B. globigii adhesion to the plasma-polymerized coating. Our TW arrays, when coated with either the SAM or plasma-polymerized PEG film, are effective at reducing adhesion to polystyrene beads as well as both Bacillus species. Lastly, our bioparticle recovery, as gauged by spectrophotometry, improves by as much as one order of magnitude when we coat flow chambers with our plasma-polymerized film.

We studied the use of nanopatterned hydrogels as a possible foundation for medical devices for the detection of Staphylococcus Aureus. Nanopatterned hydrogels, approximately 200 nm in diameter, were created by locally crosslinking dry amine-terminated poly(ethylene glycol) [PEG] (6000 Da) thin films using a focused electron beam. These gels then had a dry height of 50 nm and a swell ratio of about five. They were patterned into arrays with approximately 500 nm inter-gel spacing. These arrayed gels were functionalized with Immunoglobulin G [IgG], a biomolecule that binds Protein A. We are interested in seeing whether these arrayed gels can be used for bacterial capture and subsequent detection. We show, using an assay that binds IgG to Protein A expressing Staphylococcus Aureus [S.Aureus], that nanopatterned hydrogels can indeed be used as probes for detection. We further show that the specificity of our assay by using a knockout variant of S.Aureus that doesn't express Protein A as a negative control.