Nanostructured materials are attractive candidates for advanced friction and wear-resistant coatings due to their potentially enhanced mechanical properties. We have developed a one-step method called hypersonic plasma particle deposition [1] to produce and deposit nanoparticles using a thermal plasma reactor. Particle synthesis is achieved by dissociating vapor phase reactants in the plasma, and quenching the hot gas in a supersonic nozzle expansion. Particles are deposited on a substrate by hypersonic impaction to form a film, or are deposited as micropatterns using a process called focused particle beam deposition [2]. In-situ particle size distribution measurements are performed using a sampling probe interfaced to an extraction/dilution system for measurement by a scanning electrical mobility spectrometer.

In this paper, we introduce a novel methodology to determine the size and structure of nano-particles on a surface. We present an analysis, dubbed Elliptically Polarized Surface-Wave Scattering (EPSWS) approach, to show that 5–10 nm size particles on or above an interface can be characterized by using the scattered surface plasmon (SP) or evanescent waves. We present an analysis to show that the scattering matrix elements of the evanescent waves scattered by the nano-particles on or near an interface can be used for characterization of nano-size particles.

Azobenzene is a chemical structure that directly transmits energy of ultraviolet (UV) light, through an isomerization between the trans and cis states of a double bond between two nitrogen atoms, to a mechanical effect that reduces its molecular length from 9.0 Å to 5.5 Å [1]. This phenomenon has been applied in the fabrication of photo-deformable polymers, where monomers containing azobenzene were polymerized to form gel-like materials [1, 2, 3]. The mechanism of photo-isomerization could be very promising for the field concerning nano/micro-electro-mechanical-system (MEMS/NEMS) [4]. Layer-by-layer (LBL) method [5, 6] is a method to form thinfilms of nanometer-scale thickness through a series of adsorptions of poly-anions and poly-cations onto a charged template. 3-dimensional (3D) hollow shells can be formed by casting the LBL film onto small particles and subsequently etching away the particles. [7–11]. This report is about a combination between the photoisomerization phenomenon and LBL method. Silica micro-spheres (6.84 μm in diameter) were used as templates. In a series of LBL procedures, poly- (1- 4- 3 carboxy- 4- hydroxyphenyl azobenzene sulfonaide-1, 2-ethanediyl, sodium salt) (PAZO) and poly-allylamine hydrochloride (PAH, a poly-cation) solutions were alternatively deposited onto the surfaces of the micro-spheres. Details of the procedures followed reference [9]. After 20 PAZO/PAH double layers were formed, we etched away the SiO 2 cores by using 6:1 buffered hydrofluoride acid (BHF) and successfully formed 3-dimemsional (3D) hollow shells (Figure 1). We used a 355 nm Nd:YAG pulse-laser to irradiate the micro-shells. The microshells contracted anisotropically under the laser irradiation, and the shape of microshells changed from spherical to ellipsoidal. The long axes of the contracted microshell are parallel to the direction of the polarization of the UV laser (Figure 2). We believe that this anisotropic deformation is generated from a polarization dependence of the photo-isomerization rate of the azobenzene groups in the microshells. The deformed micro-shells were tested by irradiation of a 532nm pulse laser. The contraction, however, is not recoverable even through cis-trans isomerization was shown generated by visible-light irradiation [3]. To solve this problem, further study is needed to investigate the details of the micro-shells’ deformation. Nevertheless, we think it is quite possible that the irreversibility was resulted from the migrations and re-adhesions between the polyelectrolyte molecules during the UV irradiation. We believed that this kind of technique is very promising for the development micro and nanomachines (MEMS/NEMS). For instance, the large volumic shrinkage of the micro-shells could be applied to the field concerning nano-robots, artificial muscles, or drug delivery systems.

We are investigating ballistic impact assembly of nanoparticles to form a new class of materials for superhard coatings and micromolded MEMS parts. Nanoparticles are generated by dissociating vapor-phase reactants injected downstream of a thermal plasma and expanding the resultant flow through a converging nozzle into a low-pressure chamber. The nanoparticle-laden gases achieve hypersonic velocities due to the pressure difference between the reaction region (450 torr) and the low-pressure chamber (∼2 torr). Particles are deposited by one of two processes: (a) by placing a substrate 20mm downstream of the flow, which results in a bow shock at the substrate and high impact velocities (calculated to be over 2000 m/s for a 20 nm SiC particle): termed as high-rate deposition, (b) by focusing the particles into a tight beam (width of ∼35 (μm) using aerodynamic lenses, and subsequent impaction on a translating substrate: termed as focused beam deposition. Thus far, nanoparticle deposits consisting of combinations of Si, Ti, C and N have been explored.

Single-cell impedance spectroscopy integrated with lab-on-a-chip systems provides a direct and minimally invasive approach for monitoring and characterizing properties of individual cells in real-time. Here we investigate the theoretical potential and limitations of this technique for analyzing single membrane-bound particles as small as 100 nm in diameter. Our theoretical model suggests a lower limit of detection for single cells on the order of a few microns.

This paper discusses the design of virtual probe tip models for use in a nano-manipulation research test-bed (NMRT). The proposed NMRT would help study the feasibility of a given manipulation technique in a virtual environment before physical experiments. For example, NMRT would be able to help users determine if a specific kind of probe tip can be used to pull out a nano-particle from a given substrate. A virtual probe tip model (for instance) would consider the given geometry and material of probe tip and simulate its behavior in a manipulation application in a physics based virtual reality environment. Such a virtual analysis and overall approach would result in considerable saving in time and financial resources with substantial application potential in medical and biotechnology fields where nanoparticle manipulation is useful. Expandability of the NMRT is made possible by designing an ‘information oriented’ or ‘information intensive’ model for a target set of nano-manipulation activities, which maps in detail various attributes related to a target nano-manipulation process [1]. In this approach, information models based on “engineering Enterprise Modeling Language” (eEML) are used. For example, consider an existing information model for interaction of a probe tip with a spherical particle; a user can use an existing information model, or modify it quickly to study the impact of two approaches (eg. manipulation strategy-A versus strategy-B, which may apply a different probe-tip for gripping). For a target nano-manipulation process (for example, the assembly of nano particles using an Atomic Force Microscope probe as a gripper), an information model can represent the core attributes influencing the target process; influencing criteria including constraints, information inputs, and physical inputs can be modeled explicitly and used to drive a target analysis or simulation activity.

The possible existence of slip of liquids in close proximity to a smooth surface is studied experimentally via the dynamics of small particles suspended in a shear flow. Sub-micron fluorescent particles suspended in water are imaged and analyzed using Total Internal Reflection Velocimetry (TIRV). For water flowing over a hydrophilic surface, the measurements are in agreement with previous experiments and indicate that slip, if present, is minimal at low shear rates, but increases slightly as the shear rate increases. Furthermore, surface hydrophobicity can be attributed for additional shear-rate dependent boundary slip. Issues associated with the experimental technique and the interpretation of results are also discussed.

Aligning carbon nanotubes in any way desired is very important for many fundamental and applied research projects. In this talk, I will first discuss how to grow them with controlled diameter, length, spacing, and periodicity using catalyst prepared by magnetron sputtering, electron beam (e-beam) lithography, electrochemical deposition, and nanosphere self-assembly. Then I will present our results of field emission property of both the aligned carbon nanotubes grown on flat substrates and random carbon nanotubes grown on carbon cloth. For the aligned carbon nanotubes arrays, I will present the preliminary results of using them as photonic band gap crystals and nanoantennae. As an alternative material of carbon nanotubes, ZnO nanowires have been grown in both aligned fashion on flat substrates and random fashion on carbon cloth. Using these ZnO nanowires, good field emission properties were observed. Furthermore, I will present our recent studies on the electrical breakdown and transport properties of a single suspended nanotube grown on carbon cloth by a scanning electron microscope probe incorporated into a high resolution transmission electron microscope. As part of the potential applications, I will also discuss our recent success on molecules delivery into cells using carbon nanotubes. Finally I will talk about our most recent endeavor on achieving thermoelectric figure-of-merit (ZT) higher than 2 using our unique nanocomposite approach. Plasma-enhanced chemical vapor deposition (PECVD) was discovered by my group in 1998 to be able to grow aligned carbon nanotubes [1]. Catalyst film was first deposited by magnetron sputtering. According to the thickness of the catalytic film, aligned carbon nanotubes were grown with different diameters and spacing, and different length depending the growth time. However, the two major drawbacks are 1) that the location of where the nantoube grows can not be controlled, 2) that the spacing between the nanotubes can not be varied too much. Therefore, we immediately explored to grow aligned carbon nanotubes with the location and spacing controls using e-beam lithography [2]. Unfortunately the cost is so high that the e-beam is not suited for large scale commercialization that requires only an average site density control not the exactly location, for example, electron source. It is the cost issue that made us to develop electrochemical deposition to make catalyst dots that can be separated more than 10 micormeters between dots [3]. With such arrays, we tested many samples for field emission properties and found the optimal site density [4]. However, for applications that require the location controls, for example, photonic band gap crystals, electrochemical deposition can not be satisfactory. It is this kind of application that led us to develop the nanosphere self-assembly technique in large scale [5]. For field emission, we found that ZnO nanowires are good field emitters comparable to carbon nanotubes if they are grown with the right diameter and spacing. Here I will discuss the field emission properties of ZnO nanowires as an alternative material to carbon nanotubes [6]. Us a special kind of carbon nanotubes made by PECVD, we discovered a highly efficient molecular delivery technique, named nanotube spearing, based on the penetration of Ni-particle embedded nanotubes into cell membranes by magnetic field driving. DNA plasmids encoding the enhanced green fluorescent protein (EGFP) sequence were immobilized onto the nanotubes, and subsequently speared into targeted cells. We have achieved the unprecedented high transduction efficiency in Bal17 B-lymphoma, ex vivo B cells, and primary neurons with high viability. This technique may provide a powerful tool for high efficient gene transfer in a variety of cells, especially, the hard-to-transfect cells [7]. Conventional transport studies of multiwall carbon nanotubes (MWNTs) with only the outmost wall contacted to the electrodes via side-contact shows that a MWNT is a ballistic conductor with only the outmost wall carrying current. Here we show, by using end-contact in which every wall is contacted to the electrodes, that every wall is conducting, as evidenced by a significant amount of current drop when an innermost wall is broken at high-bias. Remarkably, the breakdown of each wall was initiated in the middle of the nanotube, not at the contacts, indicating diffusive electron transport. Using end-contact , we were able to probe the conductivity wall-by-wall and found that each wall is indeed either metallic, or semiconducting, or pseudogap-like. These findings not only reveal the intrinsic physical properties of MWNTs but also provide important guidance to MWNT-based electronic devices [8]. At the end of the talk, if time permits, I will talk about our ongoing effort on improving the figure-of-merit (ZT) of thermoelectric materials using a nanocomposite strategy to mimic the structure of the superlattice of PbTe/PbSe and Bi 2 Te 3 /Sb 2 Te 3 hoping to reduce the thermal conductivity by a factor of 2–4 while maintaining the electrical conductivity. To make a close to 100% dense nanocomposite, we started with nanoparticles synthesis, then consolidation using both the traditional hot press and the direct current fast-heat, named plasma pressure compact, to preserve the nano size of the component particles. So far, we have seen thermal conductivity decrease by a factor of 2 in the systems of Si/Ge, PbeTe/PbSe, Bi 2 Te 3 /Sb 2 Te 3 , indicating the potential of improving ZT by a factor of 2.

In this paper we present work towards electromagnetic actuation of paramagnetic particles with three-dimensional nanocoils. Self-assembled semiconductor/metal nanocoils have been used, though the concept is applicable to other types of nancoils. The particles are paramagnetic polysterene particles with iron oxide. The feasibility of such nanoelectromagnetic actuators is investigated through nanomanipulation experiments in a scanning electron microscope (SEM). Electromagnetic fields created by nanoelectromagnets are investigated through simulation. The simulation results indicate high performance of nanocoils in terms of the achievable field gradient, a key parameter for electromagnetic actuation. Results from analysis, simulation, and experiments indicate that electromagnetic nanoactuators are feasible, and have potential applications in nanoelectromechanical systems (NEMS).

It is thought that a minus hydrogen ion is useful to the apotosis of a mitochondria and prevention of a necrosis, or prevention of the illness resulting from the oxygen radical in a human body. So, in this research, examination about the possibility and its practical use method of production of the hydrogen ion by which it was minus electrified was performed. First, the lipid bilayer as a medicine transporter of DDS (Drug Delivery System) was produced using the supercritical fluid. Next, experimental examination was performed for the purpose of enclosing the substance for hydrogen ion generating, and the substance for electronic accumulation with the inside of a lipid bilayer. Furthermore, fundamental examination was performed in order to use the enclosed minus hydrogen ion. In order to check what the electron of oxygen ion was taken into the hydrogen ion, and the minus hydrogen ion generated, electrical conductivity measurement was performed. By mixing and heating, 12CaO · 7Al 2 O 3 and metal calcium, the electron was accumulated in the inside of the reaction object of 12CaO7Al 2 O 3 . The check of accumulation of the electron (anion) inside a reaction object was judged by measurement of the electrical conductivity before and behind processing. That is, when the electron was accumulated, I thought that the electrical conductivity of a reaction object increased. Moreover, this reaction object was used as an electronic transporter. In the range of the temperature set up in the liposome production experiment, and pressure, it could not say that the influence temperature and pressure affect the determination of the particle diameter of a liposome was large, but average particle diameter was about 10 micrometers. The following conclusions were obtained as a result of conducting a fundamental experiment for the purpose of production of a medicine which made the minus hydrogen ion include inside a lipid bilayer (liposome), and a confirmation of the validity as DDS in the living body. (1) The liposome suitable for DDS was able to be obtained. (2) By using metal magnesium and metal calcium, the minus hydrogen ion was able to be accumulated in the reaction inside of the body of alumina cement.