Poly(ethylene terephthalate), or PET, has been widely used in experiments due to its excellent properties and availability in sheets as thin as 1.5 µm. Its resistance to chemical attack makes PET a good choice as an inert substrate, but makes liquid phase deposition of thin films from solution challenging. Further, attempts to deposit films from the vapor phase have shown limited success. High quality PET films are desirable, as PET is transparent, hydrophobic, amenable to micropatterning, and is well characterized. As such, PET films are suited for use in microdevices. We report on liquid phase deposition of PET films, and on characterization of the films using optical methods.

Biodegradable magnetic nanoparticles were synthesized using Poly(L-Lactic Acid) and magnetite nanoparticles (∼14 nm) at different dosages, and then these nanaoparticles (nanocomposites) and pure magnetic particles were targeted in external magnetic fields by changing the test parameters. The magnetic field test results showed that magnetic saturation, fluid speed, magnetic field distance and particle size were extremely effective for a magnetic guidance system that is needed for an effective drug delivery approach. Thus, it is assumed that such nanoparticles can carry drugs (chemotherapy) to be able to cure cancer tumors as well as many other diseases.

Encapsulation of DNA molecules inside carbon nanotubes (CNT) in water were performed under the conditions of 400K and 3Bar. Double stranded DNAs of 2kb and 400bp in length, and single stranded oligonucleotides of 60bp in length were selected as target molecules. Au and Pt nanoparticles and fluorescent dye Cy3 were used as tags. Agarose gel electrophoresis was used to remove DNA molecules attached on the outside walls of CNTs. Laser confocal microscopy, scanning electron microscopy (SEM), high resolution transmission electron microscopy (HR-TEM), energy dispersive x-ray spectroscopy (EDX) were employed to confirm the encapsulation process. The results demonstrated that DNA molecules attached to the outside of CNTs can be removed by electrophoresis. Confocal microscopy and HR-TEM observations as well as EDX analysis confirmed that the Cy3-labelled DNA molecules, Au-labelled oligonucleotides and Pt-labelled DNA fragments can indeed be encapsulated inside CNTs. These experimental results support our earlier molecular dynamics simulations on encapsulating oligonucleotides inside CNTs. The DNA-CNT hybrids could be further explored for potential applications in bio-nanotechnology.

Two dimensional photonic crystals of titanium dioxide is expected to have many advantage compared with photonic crystals of semiconductors, e.g., silicon and GaAs. For example, low optical loss in the near infrared region used for optical communication, low thermal expansion, and its refractive index which is close to that for optical fiber are attractive advantages. However, it is difficult to create micro-nano structure in titanium dioxide because micro-fabrication technique for semiconductor is not available for titanium dioxide. As the first step we calculated photonic band gap of titanium dioxide rod-slab on SiO2. Also, band gap percent against thickness of the rod-slab was examined. Finally, we confirmed the most suitable structure of 2D photonic crystals. Deep x-ray lithography technique was employed for create a very deep and precise template of PMMA. Then, liquid-phase deposition was used to faithfully deposit a tightly packed layer of titanium oxide onto the template. Finally, the template is selectively removed to obtain a photonic nano-structure. We also calculate photonic band gap on the 3D-structure of TiO2. A template for the most appropriate structure was fabricated by the method proposed by Yablonovitch. By using of the same method, it was successful to obtain 3D structure of TiO2. Refractive index of obtained TiO2 followed by heating at 700°C was determined to 2.5 which is close to that for anatase phase.

We propose a novel concept, namely, delta-doping of nanowires, to control the carrier mobility in nanowires. Different from the traditional doping, our approach features doping of a nanowire only on its surface. Our calculations based on Anderson models for nanowires with surface disorder showed remarkably different results from the traditional doping where impurities are distributed inside the nanowire. We found that there exist transition energy levels similar to the mobility edges in three-dimensional disordered systems. If the Fermi energy is below the transition energy level, the delta-doped nanowire is simply an insulator. But once the Fermi energy exceeds this energy level, the carrier mobility increases significantly. The transition levels are almost independent of the degree of disorder in the regime of strong disorder.

In recent years, II-VI compound semiconductor nanoparticles synthesized in a liquid solution have been shown to possess unique optoelectronic properties which are highly attractive for the fabrication of various sensors based on the optical signal readout scheme. The challenge has been to immobilize these nanoparticles into films on solid surfaces, i.e. on a chip, so that they do not suffer any property deterioration as a sensing medium. In the presented work, synthesis of CdS nanoparticles in reverse micelle solution using AOT surfactant as a stabilizer has led to particles with relatively bright photoemission identified as originating from both shallow and deep traps inside the bandgap. Moreover, slightly altering the preparation procedure has produced samples with two distinctive crystal structures. Both types of CdS nanoparticles suspended in commonly utilized solvents such as chloroform and hexane were subject to chemical quenching when various organic compounds were introduced into the solution, demonstrating the sensitivity of trap states to their chemical environment. However, the two structures have shown very different optical properties. While post-synthesis treatment had no effect on one type of particle, the other type was able to undergo a photochemical reaction via prolonged UV irradiation, which resulted in an increased luminescence quantum yield ÖL from 2% to 14%. The same particle type was also responsive to thermal treatment, showing even higher values of ÖL (∼40%). The CdS/AOT particles have been cast into thin films by spin-coating on a Si wafer. Coating parameters have been investigated in order to achieve optimal control over the film thickness, uniformity, overall film durability, etc. These nanostructured films capped with various porous polymeric and sol-gel protective coatings were exposed to a series of organic compounds. Photoluminescence data collected for these samples served for identification of the compounds and their concentrations. This paper offers the discussion of photophysical response in CdS nanoparticle-based thin films with respect to development of novel nanostructured opto-chemical sensors.

Long-range ordered arrays of vanadium dioxide nanoparticles are fabricated by pulsed laser deposition in a patterned layer of poly(methyl methacrylate) resist. The two- dimensional arbitrary pattern is created by focused ion beam exposure of the resist, followed by pulsed laser deposition and thermal annealing. Interaction of light with the nanoparticles is controlled by their geometrical arrangement as well as by the difference in optical properties displayed between the metallic and semiconducting phases of VO2. Arrays like this open opportunities to study optical resonances and interactions for nanoparticles in close proximity, in the framework of the metal-semiconductor phase transition in VO2.

We made photonic crystals composed of artificial opals infiltrated with ZnS semiconductor nanocrystals by using self-assembly and solvothermal methods. Scanning electron microscopy images show that the silica spheres exhibit a well-ordered arrangement and the ZnS nanocrystals grow homogenously inside the opal matrix and the as-synthesized ZnS nanocrystals reveal a cubic phase from X-ray diffraction pattern. Furthermore, the optical properties of the infiltrated opals with different ZnS filling ratio are also studied by transmission spectroscopy respectively. It is proposed that the position of the stop band can be easily designed by controlling the infiltration ratio of ZnS. These results demonstrate an effective and practical route to obtain high-performance photonic crystal structures.

We are building a biosensor based on ion channels inserted into lipid bilayers that are suspended across an aperture in silicon. The process flow only involves conventional optical lithography and deep Si reactive ion etching to create micromachined apertures in a silicon wafer. In order to provide surface properties for lipid bilayer attachment that are similar to those of the fluorocarbon films that are currently used, we coated the silicon surface with a fluoropolymer using plasma-assisted chemical vapor deposition. When compared with the surface treatment methods using self-assembled monolayers of fluorocarbon chemicals, this novel approach towards modifying the wettability of a silicon dioxide surface provides an easy and fast method for subsequent lipid bilayer formation. Current-Voltage measurements on OmpF ion channels incorporated into these membranes show the voltage dependent gating action expected from a working porin ion channel.

Controlled structuring of electrode surfaces on a microscopic scale is expected to decrease the impedance and improve the current injection capabilities of neural stimulation electrodes. We have identified conditions for the fabrication of micro-bumps on platinum-iridium alloy surfaces by means of KrF excimer laser (λ=248nm) irradiation under ambient conditions. A regular array of closely spaced micro-bumps with diameters of about 5µm and heights of about 3µm was generated on the polished face of a platinum-20%iridium wire with a diameter of 75µm. A projection system with a demagnification factor of 9 was used to image a mask with a pattern of circular-holes on the polished face of the wire. Several thousand pulses at a repetition rate of 10Hz and a fluence of 3.0 J/cm2 were applied to produce the micro-bumps. The modified electrode surfaces were studied by optical microscopy and scanning electron microscopy, and the results show the formation of micro-bumps of reproducible shape. Simple two-electrode AC impedance measurements in physiological saline in the frequency range of interest to neural stimulation applications show a considerable decrease in the impedance of micro-structured electrodes with respect to the impedance of a polished electrode.

Previous publications demonstrated the sensibility of the bacteria, when these were reproduced in mediums that contain nanoparticles of luminescent silicon. The mentioned effect takes place in the development of a bacteriological sensor. The present investigation is centered on the study of the growth curves of E. coli and C. xerosis, but now in the presence of nanosize particles of Cobalt Ferrite (CoFe2O4) which were produced by the co-precipitation method in a watery phase. These nanoparticles present ferromagnetism characteristics (coercivity at room temperature among 600-5000 Oe for a size around 15-40nm). The experiment results evidence that the adaptation period of the bacteria, in contact with a stable suspension of nanoparticles of Ferrite, shows a growth curve of above the one obtained in absence of the nanoparticles (standard curve). The probable interaction of the electric polarity that these possess should be involved with the observed phenomena.

The mechanical properties of the thin film materials used in RF-MEMS are crucial for the reliability and proper functioning of the devices. In this paper we study a large number of aluminum alloys as possible RF-MEMS thin film materials. The yield strength and creep properties are measured using nano-indentation. The results show that the mechanical properties of thin aluminum films can be improved substantially by alloying elements. Of the alloys studied in this paper, AlCuMgMn in particular seems quite promising as a thin film material for RF MEMS, having both high yield strength and little creep. Using X-ray diffraction and electron microscopy, the observed effects are partly explained.

In this research, Atomic Force Microscopy (AFM) is used to investigate living neurons. Three-dimensional images of developing and dying neurons have been obtained, providing neuroscientists their first views of these dynamic structures. The unparalleled resolution provided by AFM reveals dorsal root ganglion (DRG) cells to be more complex and variable than anticipated. AFM is also used to physically contact or manipulate the cell, and thus perturb its development, and/or to measure important physiologically parameters such as surface pressure. Neural cell damage is induced by the AFM tip, which is subsequently used to image the cell's morphological response. A 3-D view of the neural cell collapse, due to this insult, suggests alternative ideas concerning acute neuronal (cellular) sealing and repair. Repair of the injured neuron using electric fields and biomolecules is also investigated, supporting clinical trials for paralysis research. AFM force measurements are used to monitor cellular activity and membrane interactions during various stages of the neural cell life cycle. The full versatility of AFM will be applied to further the understanding of neurogenesis and neurotrauma.

Gold nanoparticles supported on carbon nanotubes (CNTs) were prepared by using electroless plating technique. High-resolution transmission electron microscopy (HRTEM) has shown that spherical gold nanoparticles were homogeneously dispersed on the surfaces of the carbon nanotubes with a distribution of particle sizes sharply at around 3-4 nm in diameter. The results presented in this work will probably provide new catalysts with better performances.

We have been investigating conversion of syngas (CO: H2) to higher alkanes [Fischer-Tropsch (F-T) Process] in 5 μm and 25 μm channel microreactors coated with sol-gel encapsulated Fe/Co-nanocatalysts. These nano-metal-catalysts were incorporated into the sol-gel matrix by two methods: 1) metal nitrate solutions; 2) metal oxide nanoparticles. Characterization of these catalysts containing Co and Fe in alumina and silica sol-gel has been carried out by several techniques. The surface area measurements by BET method show an average specific surface area of 285 m2/g for alumina and 300 m2/g for silica sol-gel encapsulated catalysts. In order to optimize the sol-gel preparation and deposition in the microchannels, the elemental composition of sol-gel encapsulated catalyst was examined by EDX. The SEM and AFM images of the reactors before and after deposition of the catalysts have also been studied. Hydrogenation-reduction efficiency of the activated Fe-Co catalysts and the level of poisoning after the reaction were estimated using a vibrating sample magnetometer (VSM). The result suggests more efficient reduction in the case of the nano-particle metal oxides compared to that derived from metal nitrate solutions. In overall, 85% of the catalyst is poisoned after 25 hrs of catalytic reaction. The surface area and the syngas conversion results indicate that silica sol-gel matrix may be a better catalyst support. For alumina sol-gel support, higher conversion of syn-gas is observed with 25 μm microreactor channels. For silica sol-gel, syngas conversion as high as 73% has been achieved by adding Ru as a promoter to the Fe/Co catalyst mixture.

The mechanical properties of thin film are very critical for the performance of MEMS devices. Since Poly-silicon film is of great use in MEMS, this study investigates the surface modification by various plasma treatments to finely tune the chemical and mechanical properties of poly-silicon film. Various plasma treatments, including H2, O2, and NH3, were implemented to modify the original Si-Si film bonding, Young's modulus, and hardness of poly-silicon film. These were significant Si-O, Si-OH/Si-H and Si-NH2/Si-N bonds formed after O2, H2 and NH3 plasma treatment, respectively. According to the H analysis from SIMS depth profile of, the thickness of surface modified layer would be ranged from 50 to 120 nm. In summary, the surface modification with H2 plasma can reduce the elastic modulus of poly-silicon film for about 32.3%; moreover, the following vacuum annealing will further reduce the elastic modulus for about 60.2%. Therefore, surface modification with an adequate plasma treatment would be an effective method to change the chemical and mechanical properties of poly-silicon film.

Impedance measurements on arrays of microelectrodes can provide information about the growth, motility, and physiology of cells growing on the electrodes. In this talk, we report recent results obtained for the growth of 3T3 mouse fibroblasts and HCT116 human cancer cells on gold electrodes approximately 0.4 mm2 in area. Cells produce a characteristic peak in the impedance change plotted as a function of frequency. With the aid of electrical modeling of the cell-electrode system, the details of the changes in the measured impedance can be correlated to the cell size, fractional electrode coverage, and cell-electrode gap. In particular, comparison of impedance measurements of these two cell types show clear differences in the growth rate and the ratio of the cell-electrode gap to the cell size. In addition to presenting these experimental results illustrating the utility of electrode impedance measurements, we will outline the issues encountered when electrodes are scaled to cell size and incorporated into a matrix-addressed array.

There is a need for microminiaturized cell-culture environments, i.e., NanoLiter BioReactors (NBRs), for growing and maintaining populations of up to several hundred cultured mammalian cells in volumes three orders of magnitude smaller than those contained in standard multi-well screening plates. Reduced NBR volumes would not only shorten the time required for diffusive mixing, for achieving thermal equilibrium, and for cells to grow to confluence, but also simplify accurate cell counting, minimize required volumes of expensive analytical pharmaceuticals or toxins, and allow for thousands of culture chambers on a single instrumented chip. These devices would enable the development of a new class of miniature, automated cell-based bioanalysis arrays for monitoring the immediate environment of multiple cell lines and assessing the effects of drug or toxin exposure. The challenge, beyond that of optimizing the NBR physically, is to detect cellular response, provide appropriate control signals, and, eventually, facilitate closed-loop adjustments of the environment--e.g., to control temperature, pH, ionic concentration, etc., to maintain homeostasis, or to apply drugs or toxins followed by the adaptive administration of a selective toxin antidote. To characterize in a nonspecific manner the metabolic activity of cells, the biosensor elements of the NBR might include planar pH, dissolved oxygen, and redox potential sensors, or even an isothermal picocalorimeter (pC) to monitor thermodynamic response. Equipped with such sensors, the NBR could be used to perform short- and long-term cultivation of several mammalian cell lines in a perfused system, and to monitor their response to analytes in a massively parallel format. This approach will enable automated, parallel, and multiphasic monitoring of multiple cell lines for drug and toxicology screening. An added bonus is the possibility of studying cell populations with low cell counts whose constituents are completely detached from typical tissue environment, or populations in controlled physical and chemical gradients.

Electroactive polymers (EAPs) are capable of converting energy in the form of electric charge and voltage to mechanical force and movement and vice versa. Several electroactive polymer actuator materials whose responses are controlled by external electric fields, e.g. poly(vinylidene fluoride-trifluoroethylene) based fluoroterpolymers, have generated considerable interest for use in applications such as artificial muscles, sensors, parasitic energy capture, integrated bio-microelectromechanical systems (BioMEMS) and microfluidic devices due to their high electric-field induced strain, high elastic modulus, high electromechanical coupling and high frequency operation, etc. Scaling the EAP down into microsystems is one of the promising trends of EAP actuators and sensors especially for biomedical engineering. The combination of micro-optics and integrated BioMEMS, referred to as bio-micro-opto-electromechanical systems (BioMOEMS), makes a new opportunity for innovation in the EAP field. We present an approach to the fabrication of low-cost, large-stroke deformable micromirrors based on high performance electroactive polymer film microactuator arrays. Integrated Optic-BioMEMS based on electroactive polymer deformable micromirror (EAPDM) technology provide potential applications in biomedical optics such as ophthalmology (retinal imaging and vision care) and cancer detection and treatment.

A novel approach to making a material with negative index of refraction in the infrared frequency band is described. Materials with negative dielectric permittivity ε are utilized in this approach. Those could be either plasmonic (metals) or polaritonic (semiconductors) in nature. A sub-wavelength plasmonic crystal (SPC), with the period much smaller than the wavelength of light, consisting of nearly-touching metallic cylinders is shown to support waves with negative group velocity. The usage of such waves for sub-wavelength resolution imaging is demonstrated in a numerical double-slit experiment. Another application of the negative-epsilon materials is laser-driven near field nanolithography. Any plasmonic or polaritonic material with nega- tive ε = –εd sandwiched between dielectric layers with εd > 0 can be used to significantly decrease the feature size. It is shown that a thin slab of SiC is capable of focusing the mid- IR radiation of a CO2 laser to several hundred nanometers, thus paving the way for a new nano-lithographic technique: Phonon Enhanced Near Field Lithography in Infrared (PENFIL). Although an essentially near-field effect, this resolution enhancement can be quantified using far-field measurements. Numerical simulations supporting such experiments are presented.