We report theoretical and experimental studies on the metal-dielectric photonic crystal structure, which is constructed by the self-assembly of metal-coated nanoparticles. The finite- difference time-domain (FDTD) simulations were carried out to predict the width and position of the 3D photonic bandgap. For fabrication, we first prepared gold-embedded silica nanoparticles containing extremely small gold nanoparticles. The core particles are then immersed in a gold- containing solution in which the gold shells were formed by subsequent reduction. Formation of continuous shells was confirmed by scanning electron microscope (SEM) and the optical response due to the surface plasmons. We also performed self-assembly of both the gold- embedded core particles and metal-coated particles. SEM micrographs showed the formation highly ordered structures. The optical reflectance spectra exhibited shifts of the Bragg reflection peak due to the change in refractive index produced by gold nanoparticles.

As microcomponents in engineered systems, biological muscles have unique advantages such as large force transduction, utilization of biochemical fuel, and self-assembly from single cells, over other inorganic actuators for biomedical engineering applications. Successful integration of muscles with inorganic fabricated structures and electronics promises the capability of precisely characterizing muscles' mechanical properties and fabricating self-assembled controllable autonomous structures powered by ubiquitous glucose. However, the use of extracted muscle tissue from animals on these devices is impractical and inefficient, as the tissues must be dissected and incorporated into each device by hand with crude interfaces between the biological tissue and inorganic materials. Integration of muscle with fabricated structures would be optimally achieved through self-assembling muscle cells on MEMS. The construction of self-assembled muscle-powered MEMS structures is complicated by the stringent requirements to spatially direct the cell growth, control the tight connection of these differentiated structures with MEMS structures, and enable the cells and the integrated hybrid freedom to move. Conventional and soft photolithography techniques have been extensively employed to pattern the growth of a variety of cell types and investigate their interaction with substrate in the micrometer level. However, all studies are only suitable for patterning static cells on an immobile surface, so a novel system of spatially patterning the contractible cells must be developed to enable the cells and the integrated hybrid devices to be free to move.

We present a novel system of self-assembling myocytes on MEMS devices. This system has shown its capability of spatially and selectively directed growth and differentiation of myocytes into single muscle bundles, attachment of these functional bundles to MEMS structures, and the controlled partial release of the resultant hybrid devices. Two groups of self-assembled muscle-MEMS devices, force-measuring cantilevers and muscle-powered microrobots have been created. Here the further detailed studies of this system are discussed, especially the concept of the self-assembly and the material interfacial problems in this system.

It has been established that material surface topography can have a significant effect on biological cell adhesion, in the absence of changes in surface chemistry. Such investigations were typically performed using surface features with size on the order of microns, comparable to the dimensions of the cells. It has been demonstrated that sub-micron sized topographies that cannot be created via contact lithography also influence cell behavior. The ability to affect cell adhesion is a prime consideration in the development of novel biomaterials. This study reports a two-stage replication molding process for fabricating ordered sub-micron sized features over a large area of biomedical polyether(urethane urea). Such a technique has great applicability in the area of long-term implantable materials as a method for influencing cell-material interactions.

We investigated the fabrication of a 3D colloid crystal assembled in a layer-by-layer fashion on a template substrate. This method of assembling an ordered structure offers flexibility in the choice of crystal orientation, because of the template, and the capability to insert a “defect” layer to introduce defect modes in the stop bands of the crystal. The assembly of layers of 4.4 νm polystyrene microspheres on the patterned (100) substrates was studied using a combination of evaporation and chemical binding. It was observed that the ordering process depends on the physical parameters of the template such as well size and depth. A good adhesion of the beads to the template required chemical functionalization of the substrate.

Fabrication of 2-D and 3-D photonic bandgap (PBG) structures on silicon substrates using laser-assisted nanoimprinting of silica particles has been investigated. Monolayers of silica particles, with different diameters ranging from 160 nm to 5 νm, were deposited on silicon substrates by self-assembly. A quartz plate, which is transparent to the laser wavelength of 248 nm, was tightly placed on the substrate surface. A KrF excimer laser beam with the wavelength of 248 nm was vertically irradiated on the quartz/nanoparticle/silicon structure. The silica particles were imprinted into silicon substrates by the quartz to form a 2-D PBG structure due to the transient Si surface melting during the laser pulse. 3-D PBG structures can be fabricated by directly imprinting multilayer self-assembled silica particles into Si substrates. They can also be fabricated by repeating a process cycle of silica nanoparticles self-assembly, amorphous Si layer deposition, and simultaneous laser melting, imprinting and recrystallization.

A method to fabricate biocompatible polymer microfluidic systems with integrated electrical and fluid functionality has been established. The process flow utilizes laser ablation, microstenciling, and heat staking as the techniques to realize multi-layered polyimide based microsystems with microchannels, thru and embedded fluid / electrical vias, and metallic electrodes and contact pads. As an application of the fabrication technology, a six layer multi-functional cellular analysis system has been demonstrated. The electrophysiological analysis system contains fluid microchannel / via networks for cell positioning and chemical delivery as well as electrical detectors and electrodes for impedance spectroscopy and patch clamping studies. Multiple layers of 50.8µm thick Kapton® sheets with double-sided polyimide adhesive layers were used as the primary material-of-construction. Microchannels with widths of 400µm as well as thru hole vias with 3.71µm diameters (aspect ratios of over 12:1) were laser ablated through the polyimide sheets using an excimer laser and a CO2 laser. Electrical traces and contact pads with features down to 20µm were defined on the flexible polyimide sheets using microstenciling. The patterned layers were bonded using heat staking at a temperature of 350°C, a pressure of 1.65MPa for 60 minutes. This multi-layer technology can be used to create microfluidic devices for many application areas requiring biocompatibility, relatively high temperature operation, or a flexible substrate material.

Single square voltage pulses were used to enhance by 7 and 9 orders of magnitude the rate of covalent immobilization and hybridization, respectively, of single stranded DNA probes on a chemically functionalized thin film surface (silicon dioxide) using 2 mm size electrodes. These electrodes were scaled down to 20 μm. Photolithography was used to define the electrode voltage line, ground line, and functionalized thin-film area on a plastic substrate (polyimide). At all electrode dimensions, electric field-assisted DNA immobilization and hybridization can be achieved in the microsecond time scale, far faster than the 2 hr or 16 hr needed for immobilization and hybridization, respectively, without the electric field. Pulse conditions optimized with the large-size electrodes (2 mm) were used in the microelectrodes.

We describe the novel application of light coupling masks (LCM) in the lithographic patterning of fine structures in diamond films. A PDMS mask was used in the exposure of complex patterns of gratings in AZP 1205 resist on a substrate of Al/ diamond. The profiles of these grating patterns were then modified on a localized scale by a process of reflow of the resist. We report on the transfer of the patterns formed in resist by the LCMs into the diamond film using a sputtered Al layer as a mask. The two-stage process comprised etching of the pattern into the Al followed by transfer into the diamond film using CF4/ O2 and CHF3/ O2 gases. The presence of O2 in the CF4/ O2 and CHF3/ O2 gas mixtures produced Al oxides on the surface of the mask. The etch selectivity of the mask was greater in CF4/ O2 than in CHF3/ O2 gases and was only weakly dependent on the concentration of O2 (0-12 sccm).

Recent progress in microfabrication of biodegradable materials has resulted in the development of a three-dimensional construct suitable for use as a scaffold for engineering blood vessel networks. These networks are designed to replicate the critical fluid dynamic properties of physiological systems such as the microcirculation within a vital organ. Ultimately, these 3D microvascular constructs will serve as a framework for population with organ-specific cells for applications in organ assist and organ replacement. This approach for tissue engineering utilizes highly engineered designs and microfabrication technology to assemble cells in three-dimensional constructs which have physiological values for properties such as mechanical strength, oxygen, nutrient and waste transport, and fluidic parameters such as flow volume and pressure.

Three-dimensional networks with appropriate values for blood flow velocity, pressure drop and hematocrit distribution have been designed and fabricated using replica molding techniques, and populated with endothelial cells for long-term microfluidic cell culture. One critical aspect of the fluid dynamics of these systems is the shear stress exerted by blood flow at the walls of the vessel; a key parameter because of well-known mechanotransduction phenomena from mechanical shear forces which govern endothelial cell behavior. In this work, we report the design and construction of three-dimensional microfluidic constructs for tissue engineering which have uniform wall shear stress throughout the network. This type of control over the shear stress offers several advantages over earlier approaches, including more uniform seeding, more rapid achievement of confluent coatings, and better control over endothelial cell behavior for in vitro and in vivo studies.

Anatase inverse opal was synthesized both in the powder form and in the thin layer by means of templating with latex spheres. The voids between close-packed latex particles were filled via deposition from the titanium (IV) isopropoxide solution, electrochemical deposition from the solution of TiCl3, and liquid phase deposition from the (NH4)2TiF6 solution. The resulting material exhibited a regular fcc ordering of macropores surrounded with the framework consisting of the anatase nanocrystallites of 20 nm in size. Electrochemical performance for lithium insertion of anatase inverse opal was sluggish compared to that of non-templated anatase with more dense packing of nanocrystals.

We designed and fabricated a class of self-assembling peptides into nanofiber scaffolds. KLDL-12 has been shown to be a permissible nanofiber scaffold for chondrocytes in cartilage 3-D cell cultures. However, the biochemical, structural, and biophysical properties of KLDL- 12 remain unclear. We show that KLDL-12 peptides form stable β-sheet structures at different pH values and that KLDL-12 and RIDI-12 self-assemble into nanofibers. The nanofiber length, though, is sensitive to pH changes. These results not only suggest the importance of electrostatic attraction or repulsion affecting the fiber lengths but also provide us with useful information for rational design and fabrication of peptide scaffolds.

Magnetic and electric manipulation of a single cell in a microfluidic channel was demonstrated using a microelectromagnet matrix and a micropost matrix. The microelectromagnet matrix is two perpendicular arrays of straight wires that are separated and topped by insulating layers. The micropost matrix is an array of post-shaped electrodes embedded in an insulting layer. By controlling the current in each wire of the microelectromagnet matrix or the voltage on each electrode of the micropost matrix, versatile magnetic or electric fields were created on micrometer length scales, controlling the motion of individual cells in fluid. Single or multiple yeast cells attached to magnetic beads were trapped and moved by the microelectromagnet matrix; a single yeast cell was directly trapped and moved by the micropost matrix.

In this paper, an integrated multifunctional biochip detection system, which we call “OBMorph“, are presented. This unique system integrates several optoelectronic-based biological diagnostic tools such as an ellipsometer, a laser Doppler vibrometer/interferometer, a SPR (surface plasmon resonance) analyzer, an interference microscope, a photon tunneling microscope, an optical coherence tomography unit and a confocal scanning microscope. This OBMorph system, useful as a powerful optical metrology diagnostic tool, can be used at the beginning of sensor chip fabrication, on to signal detecting and monitoring, and to the final biological analysis. The principles and experimental results of this multifunctional biochip detection OBMorph system are presented.

In addition, an innovative SARS (Severe Acute Respiratory Syndrome) virus denaturing chemical compound that was derived using the OBMorph system to study biolinker fabrication in biochips, are discussed. Several testing strategies are presented herein which proves the effectiveness of the new chemical compound, biochip technology in denaturing the SARS virus. Analysis under an atomic force microscope confirms the actual breaking down of the virus treated by the chemical compound. The fundamentals of how the chemical compound denatures the virus and renders it toxicity useless, is based on principles of nanotechnology and bio-mechanics. Results from preliminary studies show that this denaturing principle can be also effective against other deadly viruses and even bacteria. Some design strategies and innovative working mechanisms derived from study of this chemical compound which can denature the SARS-CoV, are also discussed.

Noble metal nanoparticles and nanoshells support surface plasmons at optical frequencies. These resonances, known as localized surface plasmons (LSPs), are sensitive to the dielectric properties of the environment and, in particular, to the refractive index of the material close to the surface of the particle. This sensitivity can be exploited in molecular detection systems that use nanoparticles functionalized with receptors to (a) bind target molecules and (b) optically transduce the resulting change in the dielectric environment. Optimization of an optical nanoparticle sensor involves tailoring the particle to the target so as to maximize the sensitivity of spectroscopic features to the dielectric variation associated with binding of target molecules to the particle surface.

A novel microfluidic structure based on the electroosmotic guiding of reagent streams is presented that can be used as a fully adjustable diffusion based microreactor. The position and the width of two aqueous reactant streams entering a laminar-flow chamber can be controlled individually by changing the flow ratio of three parallel guiding streams containing buffer only. To control the intensity of product formation, the overlapping area between the diffusion regions of the two different reagent streams can be adjusted. This article describes the fabrication and experimental characterization of the device.

We present application of low coherence interferometry to characterization of ultra-thin MEMs structures such as membranes in micro-machined devices.

Hybrid nano-devices based on linear protein molecular motors working on micro/nano-engineered surfaces that operate in a “cargo architecture”, i.e. motor functionalized nano-objects running on nano-tracks, offer more opportunities than the inverse “sliding architecture” because it fully uses the information regarding directionality which is encoded in tracks, i.e. actin filaments or microtubules. However, this architecture requires the development of techniques for nanolithography with actin filaments (or microtubules) based on molecular self-assembly on engineered surfaces. The present contribution reports on the progress we have made regarding the building of actin nanostructures that would preserve the inherent information over extended micro-sized areas.

A novel method of making nanoscale devices in silicon dioxide on a silicon wafer has been developed in our laboratory. The method is both inexpensive and can be fully integrated with existing VLSI type electronic processing technology. The devices are defined using conventional micronscale photolithography and then reduced in scale during the processing sequence to form nanoscale structures. Further, since the structures are defined using lithography, they can be made to span the range of scales from macro to nano in one processing step. Finally, we have found that by using laser assisted chemical etches, we can “release” these very fine structures without the damage associated with wet processes such as stiction.

For the performance of certain analytical and diagnostic tasks in modern Life Science applications high throughput screening (HTS) methods are essential. Miniaturization, parallelization and automation allow to decrease consumption of expensive materials and lead to faster analyzing times. The miniaturization of total assay volumes by the use of microtiter plates as well as the microarray technology have revolutionized the field of biotechnology and Life Sciences. Neither printing of microarrays with droplet volumes of several picoliters, nor handling of precious enzymes in the upper nanoliter range can be accomplished with traditional liquid handling devices like air displacement pipettes. The development of novel low volume liquid handling devices, which are subject to current research, addresses the diverse requirements shifting steadily to lower volumes. Various novel non-contact dispensing methods in the nanoliter and picoliter range are presented and classified according to their working principles like air displacement and direct displacement methods (TopSpot®, NanoJetTM, Dispensing Well PlateTM). Properties of the various methods are compared in terms of flexibility, integration density, speed of operation, precision, addressable volume range and amenability to multi-parallel operation.

Carbon nanotube (CNT) related nanostructures possess remarkable electrical, mechanical, and thermal properties. To produce these nanostructures for real world applications, a large-scale controlled growth of carbon nanotubes is crucial for the integration and fabrication of nanodevices and nanosensors. We have taken the approach of integrating nanopatterning and nanomaterials synthesis with traditional silicon microfabrication techniques. This integration requires a catalyst or nanomaterial protection scheme. In this paper, we report our recent work on fabricating wafer-scale carbon nanotube AFM cantilever probe tips. We will address the design and fabrication considerations in detail, and present the preliminary scanning probe test results. This work may serve as an example of rational design, fabrication, and integration of nanomaterials for advanced nanodevice and nanosensor applications.