Cell engineering is concerned with the combination of engineered materials with biological cells to create useful devices. Cells in the body are organised spatially and this organisation is reflected in the shapes of the cells themselves and in how they are positioned relative to their neighbours. A necessary first step in re-growing cells to form a tissue-like implant is to re-create this original pattern in the re-grown cells.
A brief account is given of the effects of topographic and chemical patterning on the behaviour of cells.
The methods by which such patterning can be transferred into materials suitable for cell and tissue engineering are given. The advantages of using mechanical transfer in one of its many forms for this purpose are stressed.
Sub-lithographic nanowires and nanogaps were fabricated by spacer lithography (size reduction technology), which is a parallel processes for nanometer pattern generation on a wafer scale with resolution comparable to the best electron beam lithography. Sub-10nm line width is defined by using a sacrificial ultrathin film deposited by low pressure chemical vapor deposition (LPCVD), in a process similar to formation of gate sidewall spacers in CMOS processing. Furthermore, a novel method called iterative spacer lithography
(ISL) is demonstrated by alternating materials and repeating the spacer lithography multiple times in order to multiply the pattern density. Silicon structures with sub-10nm width fabricated by this process were used as a mold in nanoimprint lithography and lift-off patterning of sub-30nm platinum nanowires for use as model catalyst systems. A similar process called reversed spacer lithography (RSL) is demonstrated to form sub-10nm nanogap device and fluid channels in poly-Si. This nanogap device provides a label-free tool for DNA
hybridization detection based on measuring capacitance changes in the gap.
Metallic nanoparticle assemblies can be organized in accordance with the helical structure of the cholesteric liquid crystalline phase. The liquid crystals used having a glassy state, the nanostructures
could be examined by transmission electron microscopy. The platinum nanoparticles form periodic ribbons which mimic the well-known fingerprint cholesteric texture. The nanoparticles do not decorate the texture but create a novel structure with a larger helical pitch. The distance between the ribbons is directly correlated to the cholesteric periodicity which therefore becomes a simple control
parameter to tune the structuring of nanoparticles.
Sandia is exploring two classes of integrated systems involving bioactive materials: 1) microfluidic systems that can be used to manipulate biomolecules for applications ranging from counter-terrorism to drug delivery systems, and 2) fluidic systems in which active biomolecules such as motor proteins provide specific functions
such as active transport. An example of the first class involves the development of a reversible protein trap based on the integration of the thermally-switchable polymer poly(N-isopropylacrylamide)(PNIPAM) into a micro-hotplate device. To exemplify the second class, we describe the technical challenges associated with integrating microtubules and motor proteins into microfluidic systems for: 1) the active transport of nanoparticle cargo, or 2) templated growth of high-aspect ratio nanowires. These examples illustrate the
functions of bioactive materials, synthesis and fabrication issues, mechanisms for switching surface chemistry and active transport, and new techniques such as the interfacial force microscope (IFM) that can be used to characterize bioactive surfaces.
A design concept for nanowire-based sensors and arrays is described. The fabrication technique involves electrodeposition to directly grow nanowires between patterned thin film contact electrodes. To prove our concept, we have electrodeposited 1-μm diameter Pd single wires and small arrays. To demonstrate nanowire sensors, we have
electrochemically grown metal (Pd, Au, Pt), metal oxide (Sb2O3), and conducting polymer (polyaniline) bundled nanowires. Using Pt bundled nanowires surface modified with glucose oxidase, we have demonstrated glucose detection as a demonstration of a biomolecular sensor.
A raster multibeam lithography tool is in Etec’s roadmap to meet the stringent requirements of sub 100 nm mask fabrication. The tool leverages the long experience obtained with the ALTA laser pattern generators and the high resolution capabilities of e-beam lithography. A photocathode controlled by acousto-optic modulated 257nm laser beams is utilized to generate 32 electron beams. The beams are accelerated at 50 KV in an electron column, demagnified and focussed on the mask or wafer substrate. The performance of the photocathode and other system components will be presented together with preliminary lithographic patterning.
Systematic studies on scanning probe lithography (SPL) methodologies have been performed using self-assembled monolayers (SAMs) on Au as examples. The key to achieving high spatial precision is to keep the tip-surface interactions strong and local. Approaches include three atomic force microscopy (AFM) based methods, nanoshaving, nanografting, and nanopen reader and writer (NPRW), which rely on the local force, and two scanning tunneling microscopy (STM) based techniques, field-induced desorption and electron-induced desorption, which use electric field and tunneling electrons, respectively, for nanofabrication. The principle of these procedures, the critical steps in controlling local tip-surface interactions, and nanofabrication media will be discussed. The advantages of SPL will be illustrated through various examples of production and modification of SAM nanopatterns.
A laser manipulation technique for metal nanoparticles using an optical fiber has been developed. A micro ball lens adhered onto the flattened end of the optical fiber focuses a light beam propagated through a core. An object is trapped in the focused beam. An electromagnetic field distribution was numerically simulated for validation of the focusing lens. Calculation including an Au nanoparticle indicated that the laser trapping would be possible with this method. In the experiment, trapping of Au particles with diameter of 200nm was achieved by using a light source (Nd-YAG: 1064nm). The maximum trapping efficiency attained in the focal region was estimated to be 5.4fN/mW. Additionally, the fixation of a manipulated particle onto a glass substrate was also demonstrated. With intensifying the laser power, a laser-trapped particle is fixed on the substrate. By repetition of the procedure of laser manipulation and fixation, alignment of Au nanoparticles was achieved.
In this paper, fabrication of a fine gold grating on glass substrate is demonstrated using imprint lithography for optical elements. A Si mold with fine grating patterns is prepared using conventional IC’s process. The line widths of the gratings are varied from 1.0μm to 200nm. About 20nm thick Si3N4 film is coated on the mold surface by LP-CVD to improve hardness of the mold. The Si mold is pressed to a gold film on a glass substrate at room
temperature. To eliminate fatal fracture of the sample in pressing, the form of the sample is just aligned to the mold to avoid stress concentration at the mold edges. The gold film is plastically deformed and fine gold grating with 200nm in line width and 300nm in height is successfully fabricated on the glass plate. The cross sectional profile of the gold pattern is fine rectangular shape. Using room temperature direct imprint lithography, metal gratings are
successfully fabricated on a glass plate. This method is a promising way to fabricate fine micro optical elements by low cost.
Focused ion beams (FIB) have been widely used as a patterning lithography technique for advanced ICs and optical masks fabrication. FIB lithography has certain advantages over the direct-write electron beam lithography in terms of resist sensitivity, backscattering and proximity effects. However, combining the FIB exposure with both Top Surface Imaging (TSI) and dry etching will further extend its advantages towards anisotropic processing of thicker resist layers in comparison to those used by the conventional lithography processes. The newly developed NERIME (Negative Resist Image by Dry Etching) process combines these advantages by the incorporation of focused Ga+ ion beam (Ga+ FIB) exposure, near UV exposure, silylation and dry etching. The work described here follows our investigations into the NERIME process for nanostructure applications and outlines a simplified (two-step) process incorporating FIB exposure and oxygen dry development. The two-step modified NERIME process is a negative working TSI system for DNQ/novolak based resists. Results show that Ga+ ion beam dose higher than 800μC/cm2 at 30keV can modify the exposed resist areas as to withstand the subsequent oxygen plasma etching, thus giving formation of negative resist image. In this study, nanometer resist patterns as small as 30nm with high aspect ratio of up to 15 were successfully resolved due to the high resolution ion beam exposure and anisotropic dry development. The proposed two-step lithography scheme could be utilized for the fabrication of critical CMOS process steps, such as sub-100nm gate formations and lithography over substantial topography.
The spatial distribution of the local optical field in the photonic crystal (PC) microcavities (MC) formed from porous silicon and in MC doped by fluorescent dye is studied by apertureless scanning near-field optical microscope (SNOM). To increase fluorescence up to 100 times photonic crystals are doped by fluorescence dye Rhodamin 6G. Photoluminescence spectroscopy of porous silicon photonic crystal MC is studied by far-field and near-field probes. The spatial distribution of optical field at the cleaved edge of MC is observed in
near-field scattering and photoluminescence. The image of the spatial distribution of local optical field in near-field fluorescence at the wavelength of local optical maximum of fluorescence spectra shows the localization of radiation in MC layer.
In this paper, we introduced an optical switch MEMS with 32 I/O channels. A simple formula is given as a guideline for application in nano-MEMS mirror arrays in optical cross connects networks. Minimized MEMS optical switch cannot only be linked to standard fiber but also can be connected to any other nano-scale optical devices by our designed microlens. We consider the optical switch being scale down to nano-meter order including beam radius at waist 2 μm, the tilt angle of mirror is set as 0.1(rad), the width of nano-MEMS chip is below 1000nm and optical wavelength 1.55 μm by using our designed microlens arrays.
With the development and application of nanofabrication on nano photoelectron device, the completely oxidized thin metal film such as titanium film by Atomic Force microscope (AFM) tip induced oxidation method has been used to make various nano electric devices. It is more and more important to study the process mechanism for improving the operational stability and reliability of such nano devices. In this paper, the mechanism of AFM tip induced oxidation is analyzed with several aspects. According to the experimental results of AFM tip induced oxidation of titanium under various voltage biases and scanning speeds, we find that the height of the titanium oxidation is linear with the voltage bias and with the negative log of the scanning speed. Based on the formers’ theories, the mechanism and the theoretical modeling of AFM tip induced oxidation are improved. By setting the proper conditions such as voltage bias of 8V and
scanning speed of 0.1μm/s, good nanofabrication results with AFM oxidation of titanium are got and the oxide lines are with good aspect ratio and good continuity.