In this study, low dynamic range images (LDRIs) were produced from high dynamic range images (HDRIs) using a two-step tone mapping (TSTM) method. First, the HRDIs were constructed from a series of 15 images, that each vary in just the exposure time, through an image registration method. Then, the HDRIs were mapped into 8-bit images using the TSTM method via the use of luminance maps and bilateral filters. The proposed TSTM method was evaluated in direct comparison with three other tone mapping (TM) methods (Reinhard's photographic, Durand's bilateral and Ward's histogram equation methods) using a pairwise comparison and five-point category rating system of a set of 10 LDRIs by a panel of 10 testees. The results revealed that this proposed TSTM method produced better overall LDRIs, and was superior for the detail and color reproduction, as well as overall quality, compared to those from the other three TM methods, but was inferior to Reinhard's and Ward's methods for the tonal reproduction.
The crystalline C60 particles were synthesized into PDMS-based microwells on microarray chips using an ink-jet spotting system, and the effect of the particles on cytotoxicity was investigated using HeLa cells (human cervical carcinoma cell). It was found from SEM observations that a number of C60 particles were formed along the edges of 300μm microwells, which could have enough area to encapsulate several tens of cells in the center. The tests with HeLa cells revealed that the C60 particles irradiated green laser caused cytotoxicity, and the rate of cell death was controlled by the irradiation time. It was suggested that the cytotoxicity was induced by reactive oxygen species (ROS) generated by the C60 particles, and an effect of the ROS on the cells covered a large part of the microwell.
We have investigated the influence of surface and bulk characteristics of polymer insulators as a printed gate dielectric layer for organic field-effect transistors on the time variation of the drain current. Three components of time variation with different time scales were observed. The roughness and long-chain chemical species of the insulator surface enhanced the time variation with a time scale of several tens minutes. When the insulating polymer surface had dipoles, the drain current for organic field-effect transistors (OFETs) significantly decreased with time. This decrease in drain current occurred several hundred milliseconds from the application of the gate voltage. The dielectric relaxation of polymer gate insulators caused an increase in the drain current immediately after the application of the gate voltage and lasted for several milliseconds. Based on the observed results, we suggested an ideal polymer gate insulator to achieve printed OFETs that have stability and high performance.
In order to fabricate an electric device that is printed on a plastic substrate successfully, it is important to decrease the process temperature as much as possible. Furthermore, low-cost processes and materials need to be developed so that they have a wide variety of uses. With this in mind, we have developed a low-temperature preparation method for electric materials such as semiconductors, insulators, and electrodes. In this paper, we discuss novel techniques for preparing high-performance SiO2 using vacuum ultraviolet light and commercial Ag ink with decreased resistivity using pressure treatment in order to fabricate electric devices on reasonably priced plastic substrates. In addition, we also introduce a method for reducing the costs of developing printed devices by using Cu ink.
Micro spray mode of electrostatic inkjet has been examined experimentally for the application of precision film coating such as photoreceptors and photovoltaic cells. According to the increment of applied voltage, jetting mode change was observed for all examined liquids that were the change from dripping mode to stable cone-jet mode. Although the variation of jetting mode was qualitatively the same as that of a single nozzle, for multi-nozzle the higher voltage was required to obtain the stable jetting mode because the electric field at the tips of multi-nozzle were lower than that of a single nozzle. From coating experiments it was demonstrated that multi-nozzle could jet viscous solution to acquire thick and flat film. To apply it to the nano-film coating, considering depositing and drying conditions is indispensable in addition to the jetting process. Much finer droplets could enlarge the parameter-space for quality coating.
We demonstrate a LbL assembly using the inkjet printing of single cells and proteins to enable the fabrication of 3D human micro-tissue arrays, which are integrated structures of micrometer-sized cellular multilayers controlled at the single-cell layer level, for application of pharmaceutical assays. Introduction of automatic inkjet printing of cells and proteins must be necessary for giving an assurance of their reproducibility. The 440micro-arrays which were the integration of simplified and multilayered liver structures were successfully developed and comprehensive high-throughput assays of liver functions were performed. We found for the first time that these simplified 3D liver structures, a sandwich of endothelial cells and hepatocytes, revealed the highest functions as compared to other 3D-structures. These 3D-human tissue chips would enable the “total-human tissue models” for tailor-made drug screening.
In this article, we discuss the unique features of calamitic liquid crystals as an organic semiconductor for printed electronics, which we call self-organizing molecular semiconductors, in comparison with conventional non-liquid crystalline organic semiconductors, and how we can utilize the liquid crystallinity in device applications. In addition, we demonstrate the unique features and advantages over non-liquid crystalline materials with organic field effect transistors (OFET) fabricated with polycrystalline thin films of a highly ordered smectic liquid crystal and its FET performance for an immediate application of the liquid crystal as an organic semiconductor.