One of the important issues regarding inkjet printers is that misfiring should not occur during intermittent printing over the long run. But such misfiring was observed for some consumer printers which were used for only a short term, less than the printer's life span. So it was a major problem in view of the long-term reliability of the products. We performed detailed studies about the problem and found the cause of the misfiring. It was known that small bubbles stayed in the ink flow channels of the printer head, grew into the big bubbles, and ink quantity decreased because of narrowing ink flow paths, we then thought it was related to the phenomenon that fine ink drops could not fly out from the nozzle holes and it would perform poorly. To solve the problems, we developed a new plastic material and a new flow channel structure. The material has high-level barrier characteristics against gases such as oxygen and water vapor. And the flow channel structure had several ditches that serve as bypasses and some ribs which lead bubbles with only small growth to the center of the flow channel. In this solution, we found that the ink quantity would not decrease in the long term and it suppressed the bubble growth rate. We believe that the misfiring occurrence would decrease with these measures.

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Paper-wrinkle trouble must be straightened out to possess higher reliability on printers. However, paper-wrinkle generation mechanism and the factors associated with the mechanism remain undefined. Therefore it is not easy to solve the problem caused by paper-wrinkle. To avoid such difficulties and the development of printer products to be more efficient, a mechanism analysis of paper-wrinkle generation phenomena in fuser unit has been conducted. In order to clarify the factors of paper-wrinkle, paper handling behavior in fuser unit has been quantified with specific equipment which designed for paper-wrinkle principle analysis. The results show that the angle of wavy deformation of paper could be applied to likelihood evaluation of paper-wrinkle.

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Molecular devices have attracted growing interest as a potential candidate for future nanoscale devices. Electrical characterization of a single molecule bridging between metal electrodes is essential for the realization of molecular devices and requires the fabrication of nanogap electrodes whose gap widths are few nanometers. In this paper, we review representative methods for fabricating nanogap electrodes and report our developed methods using focused ion beams (FIBs). The presented method is based on in situ monitoring of etching steps by measuring current through patterned electrodes and on electronic termination of etching steps just after nanogap formation. By using this method, electrode gaps much narrower than the FIB spot size can be reproducibly fabricated. The minimum gap width achieved is ∼3nm, and the fabrication yield reached ∼90% for 3-6nm wide gaps. The fabricated nanogap electrodes show high insulating resistance ranging from 10GΩ to 1TΩ.

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A single molecular junction, where a single molecule is bridged between metal electrodes, has attracted wide attention since novel properties can appear due to its peculiar geometrical and electronic characters. The single molecular junction has also attracted attention due to its potential application in ultra small electronic devices. In this article, we discuss the fabrication and characterization of the single molecular junction using a model system of the single hydrogen molecular junction. The single hydrogen molecular junction has been characterized by vibration spectroscopy of a single molecule, shot noise and conductance measurements. The single hydrogen molecular wire can be fabricated by stretching the hydrogen molecular junction. Using the single hydrogen molecular junction and wire, the interaction between conduction electron and molecular vibration can be discussed in detail. Finally, we comment on the current topics of the single molecular junction.

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Insulated molecular wire made from conducting polymer and insulated cyclic molecule, and conducting polymer nanofiber in which conducting polymers simultaneously assembled are molecular nanowires with nm-scale diameter and expected to be applied for molecular nanodevices. Here, we explain electric properties of isolated these nanowires. In particular, since the crystallinity of conducting polymer nanofiber can be controlled by changing fabrication conditions, the relation between microscopic structure and electric properties was investigated and the property of field-effect transistor was evaluated. Furthermore, the relation of topology and electric properties of nanofiber and nanofiber composite film embedded in conventional polymer were studied. From these results, we considered possibilities of these materials for the nanotechnology.

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In single-molecular electronics, the charge transport properties of single-molecular junctions are utilized as an electronic device. One of the simplest molecular devices may be a single-electron transistor (SET) in which the single-electron transport appeared in the molecular junctions is used. We have been studied the device properties of “single-molecule SETs” and “nano-particle SETs”, where these devices consist of a nano gap electrode bridged by a π-conjugated molecule and gold nanoparticles covered with molecular wires, respectively. In these devices, the molecules are used as a Coulomb island or tunneling barrier. In addition, we recently proposed a new device structure that is a “dye-doped SET”, in which dye-molecules act as a floating gate. In this article, we describe the properties, advantages, and possible applications of these devices.

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Gating nanopore devices, which is composed of a nanopore with embedded nanoelectrode, are expected to be one of core devices to realize $1000 genome sequencing technologies, and identify single base molecules via tunneling current between nanoelectrodes. We have demonstrated to identify single base molecules of DNA and RNA using tunneling currents. 2 Core technologies should be developed in an effort to make gating nanopore devices fit for practical use. One core technology is to identify single DNA and RNA composed of many base molecules. We have succeeded in single molecule electrical sequencing of DNA and RNA formed by 3 and 7 base molecules, respectively. A method to control speed of single DNA passing through a nanopore is one core technology to determine speed and accuracy of sequencing. We have developed the method to control translocation speed of single DNA by three orders of magnitude using voltage between nanoelectrodes.

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