Study on Ag mesh/conductive oxide hybrid transparent electrode for film heaters.

Ag mesh-indium tin oxide (ITO) hybrid transparent conductive films were fabricated and evaluated for use in film heaters. PS monolayer templates were prepared using highly mono-dispersed PS spheres (11.2 µm) obtained by a filtering process with micro-sieves. At first, three Ag meshes with different sheet resistances (20, 100, and 300 Ω sq(-1)) and transmittances (70, 73, and 76%) were evaluated for film heaters in terms of voltage and long-term stability. Subsequently, in an effort to obtain better transmittance, Ag mesh-ITO hybrid heaters were fabricated utilizing finite ITO depositions. At the optimised ITO thickness (15 nm), the sheet resistance and the transmittance were 300 Ω sq(-1) and 88%, respectively, which indicates that this material is a good potential candidate for an efficient defroster in vehicles.

Cr-Si Schottky nano-diodes utilizing anodic aluminum oxide templates.

We have fabricated Cr nanodot Schottky diodes utilizing AAO templates formed on n-Si substrates. The diameters of the diodes were 75.0, 57.6, and 35.8 nm. Cr nanodot Schottky diodes with smaller diameters yield higher current densities than those with larger diameters due to an enhanced tunnel current contribution, which is attributed to a reduction in the barrier thickness. The diameters of Cr nanodots smaller than the Debye length (156 nm) play an important role in the reduction of barrier thickness. Also, we have fabricated Cr-Si nanorod Schottky diodes with three different lengths (130, 220, and 330 nm) by dry etching of n-Si substrate. Cr-Si nanorod Schottky diodes with longer nanorods yield higher reverse current than those with shorter nanorods due to the enhanced electric field, which is attributed to a high aspect ratio of Si nanorod.

Fabrication of room-temperature operational single-electron devices using Au nanoparticles.

Au nanoparticles (5-10 nm in diameter) single electron devices (SEDs) were fabricated utilizing both electron beam lithography and granular film deposition. Both multiple-tunnel junction (MTJ) and double-tunnel junction (DTJ) were fabricated by adjusting the number of Au nanoparticles between the electrodes. Coulomb blockade effects were clearly observed at room temperature from the MTJs. The threshold voltage of the MTJ-SED with a large gap was about 1.5 V, whereas that with a small gap was about 0.8 V, respectively. When the gap was below 20 nm, a periodic Coulomb staircase was observed from the DTJ-SED at room temperature, where the charging energy was about 0.114 eV.

Seeding cells on calcium phosphate scaffolds using hydrogel enhanced osteoblast proliferation and differentiation.

Internal pores in calcium phosphate (CaP) scaffolds pose an obstacle in cell seeding efficiency. Previous studies have shown inverse relationships between cell attachment and internal pore size, which mainly resulted from cells flowing to the bottom of culture plates. In order to overcome this structure-based setback, we have designed a method for cell seeding that involves hydrogel. CaP scaffolds fabricated with hydroxyapatite, biphasic calcium phosphate, and ß-tricalcium phosphate, had respective porosities of 77.0, 77.9, and 82.5% and pore diameters of 671.1, 694.7, and 842.8 µm. We seeded the cells on the scaffolds using two methods: the first using osteogenic medium and the second using hydrogel to entrap cells. As expected, cell seeding efficiency of the groups with hydrogel ranged from 92.5 to 96.3%, whereas efficiency of the control groups ranged only from 64.2 to 71.8%. Cell proliferation followed a similar trend, which may have further influenced early stages of cell differentiation. We suggest that our method of cell seeding with hydrogel can impact the field of tissue engineering even further with modifications of the materials or the addition of biological factors.

Highly conductive and transparent Ag honeycomb mesh fabricated using a monolayer of polystyrene spheres.

We describe the design principles and fabrication of Ag honeycomb mesh as a transparent conductive electrode using a polystyrene (PS) sphere template. Monolayers of PS spheres with different diameters, such as 600 nm, 3 µm, and 10 µm, are studied as templates to form Ag mesh with high transmittance. Since the parasitic Ag islands degrade the transmittance, both heat pretreatment and wet etching are used to control the area covered by parasitic Ag islands. The trade-off between transmittance and conductivity forces us to use larger diameter PS spheres. Ten-micron PS spheres are chosen as the template for the PS sphere monolayer, and heat pretreatment and Ag wet etching are used to demonstrate that the Ag honeycomb mesh transparent electrodes have high performance. The transmittance and the sheet resistance are 83% and 20 Ω/sq, which are comparable to commercial ITO electrodes.