Yoshiaki Imaizumi

Ultra-small site temperature sensing by carbon nanotube thermal probes

We have assembled thermal probes with single carbon nanotubes (CNTs) for sensing temperature distribution in local area. The temperature coefficient of resistance of the thermal probes shows the positive characteristics. The feasibility of the CNT thermal probes for scanning local area temperature is investigated in nanometer order. We have implemented the assembled CNT thermal probes for temperature measurement and calibration of CNT nanoheater, and demonstrated them to be novel temperature sensors.

Carbon nanotubes based position sensors

Prototypes of individual carlbon nanotube (CNT)l based position sensors are presented on the bases of the field emission from a nanotube emitter, a telescoping (inter-layer sliding) multi-walled nanotube and a sliding nanotube on an Aui substrate. These sensors are constructed by nanomanipulation and featured by their compact sizes, simple structures, andl potential high resolutions. Field emission based one is: characterized by the non-contact configuration and suitable for an approximate sensor or as a position detector for other kinds of sensors. Telescoping motion based nanotube sensors have potentially subnanometer resolution and itlt well for a nano encoder because of their potentially quantized interlayer coupling resistance. Unidirectional and reciprocating telescopic: motions have been realized and the resistance has been found1 changing linearly with the telescoping length. The perfect linearity of the resistance of a nanotube sliding on an Au substrate promises it the highest resolution in the presented three types. However, the contact nature limits its applications.

Perspective of nanotube sensors and nanotube actuators

The state of the art of nanotube sensors and nanotube actuators are overviewed according to the physical properties/effects (large aspect ratio, ultra-high elasticity, lower onset field emission, ultra-small interlayer friction, etc.) applied, number of nanotubes (single, double or multiple-array, fiber, film and bulk) involved, and configurations of nanotubes (cantilevered, supported, opened or telescoped) adopted by focusing on our recent effort at this challenging field. Deflection of cantilevered individual nanotubes based mass flow sensors, pico-Newton force sensors, and femtogram mass sensors, field emission of a cantilevered nanotube based approaching sensors, resistance variation of telescoping single nanotubes based variable resistors/position sensors, resistance variation of cantilevered dual nanotube based thermal probes, and our preliminary works on telescoping nanotube linear actuators are introduced and several typical examples are reviewed in this report.

Dry-Etching Durability of Copolymers and Polymer Blends of Vinylnaphthalene or α-Methylstyrene with Methyl Methacrylate

Dry-etching durabilities of poly(2-vinylnaphthalene-co-methyl methacrylate), the blend of poly(2-vinylnaphthalene) and poly(methyl methacrylate) [PMMA], and poly(α-methylstyrene-co-methyl methacrylate) films were studied as a function of vinylnaphthalene or α-methylstyrene content against four types of dry etching: 1) O2 plasma etching ( O2 PE), 2) O2 reactive ion etching ( O2 RIE), 3) Ar+ sputter etching (Ar SE), and 4) Ar ion beam etching (Ar IBE). Since the etching depth increased linearly with etching time the two-component polymer films were regarded to be etched uniformly without selected removal of aliphatic monomer units. Substantial enhacement of the durability was observed by incorporating or blending small amounts of aromatic moiety into PMMA for physical etching (Ar SE, Ar IBE) and physical/chemical etching ( O2 RIE) as well as chemical etching ( O2 PE). O2 RIE is a synergetic process involving both physical bombardment and chemical reaction.

Molecular Orientation and Photochemical Reaction of Organoaluminum Compounds Investigated by Buried Metal Layer Infrared Reflection Absorption Spectroscopy

The structure and synchrotron radiation (SR) irradiation effects of the low-temperature condensed layer of several organoaluminum compounds on the SiO2 surface were investigated by infrared reflection absorption spectroscopy using a buried metal layer substrate (BML-IRAS). Trimethylaluminum is a dimer at temperatures lower than 180 K, and a photoproduct having the methyl group is produced by SR irradiation. The condensed layer of dimethylethylamine alane (DMEAA) as-deposited at temperatures less than 140 K consists of randomly oriented dimer molecules, and changes to a more ordered orientation of monomer molecules at temperatures higher than 140 K. Concerning the SR irradiations, the results are different for the two different molecular orientations. Upon SR irradiations of the ordered orientation layer, a new broad vibration band, possibly assigned to the aggregation of inhomogeneous AlH stretching vibrations, appears. On the other hand, in the case of the random orientations of the dimer molecules, such a new broad band does not appear, and only an intensity decrease is observed for all bands.

Local growth of carbon nanotubes on the cantilever by chemical vapor deposition with FIB assist etching

We have controlled the local growth area of the carbon nanotubes (CNTs) on the silicon cantilever using chemical vapor deposition (CVD) with assistance of the focused ion beam (FIB) etching. By removal of the mask layer above the catalyst layer by the FIB, the CNTs were easily grown from the areas of the catalyst layer. This opens a door to the new century of the CNTs device fabrication such as, temperature sensor for the ultra small site, mass flow sensor, CNTs actuator and other various devices.

TEM Observation of the Giant Carbon Nanotube Construction Using Langmuir-Blodgett Films

Langmuir-Blodgett (LB) films, which included Fe atoms as a catalytic metal material, were used for carbon nanotube (CNT) growth by chemical vapor deposition (CVD). A new form of localized nanotube growth was observed to result in a structure called a giant carbon nanotube construction (GNC). The GNC seems to be a self-assembled knitted structure formed by CNTs. The GNC is thin (∼5 μm in diameter) and long (∼100 μm) and is quite different from a CNT bundle. A growth mechanism for the GNC was developed from the results of TEM, SEM, and Raman spectral analysis. The GNC might find applications for CNT sensors, synthetic fibers, and so on.

Recent topics of micro -and nano mechatronics

This paper focuses on the recent topics of micro and nano mechatronics. A nano laboratory-a prototype nano manufacturing system based on nanorobotlic manipulation-is presented for enabling nanotube-based micro- and nanomechatronics, such as microhano sensors and actuators, bioapplications and nano-robotics applications. Deflection of cantilevered individual nanotubes based mass flow sensors, field emission of a cantilevered nanotube based approaching sensor, dual cantilevered nanotubes based thermal probes, and telescoping motion based nanotube linear bearings and our preliminary works on actuators are reviewed.

Selective Growth Method of Carbon Nanotubes by Chemical Vapor Deposition

Carbon nanotubes (CNTs) are potentially useful for developing functional nanodevices such as thermal probes, flow sensor arrays, and AFM probes. Controlling the growth position of CNTs grown by chemical vapor deposition (CVD) is crucial to fabrication of these nanodevices. We propose an easy, non-lithographic process of making CNT sensor probes using CVD. Growth positions of CNTs were precisely controlled by depositing a patterned barrier layer above the catalyst layer. Then, the CNTs were grown from the exposed catalyst layer using CVD. This method is easily applied to assembling bridged CNTs. We used focused ion beam etching to remove the barrier layer and expose the catalyst membrane. Through the proposed method, we made a bridge of CNTs at the tip of a Si edge. This type of bridge can be used as the nanoprobes for local sensing of physical properties.

Local Growth of Carbon Nanotubes with a Simple Mask CVD Method on 3-D substrates

Carbon nanotubes (CNTs) are potentially useful for developing functional nanodevices such as thermal probes, flow sensor arrays, and AFM probes. Controlling the growth position of CNTs grown by chemical vapor deposition (CVD) is crucial to fabrication of these nanodevices. We propose an easy, non-lithographic process of making CNT sensor probes using CVD. Growth positions of CNTs were precisely controlled by depositing a patterned barrier layer above the catalyst layer. Then, the CNTs were grown from the exposed catalyst layer using CVD. This method is easily applied to assembling bridged CNTs. We used focused ion beam etching to remove the barrier layer and expose the catalyst membrane. Using this method, we made a bridge of CNTs at the tip of a Si edge. This bridge is used to fabricate several nanoprobes for local sensing