Fabrication of a Textile-Based Wearable Blood Leakage Sensor Using Screen-Offset Printing

We fabricate a wearable blood leakage sensor on a cotton textile by combining two newly developed techniques. First, we employ a screen-offset printing technique that avoids blurring, short circuiting between adjacent conductive patterns, and electrode fracturing to form an interdigitated electrode structure for the sensor on a textile. Furthermore, we develop a scheme to distinguish blood from other substances by utilizing the specific dielectric dispersion of blood observed in the sub-megahertz frequency range. The sensor can detect blood volumes as low as 15 μL, which is significantly lower than those of commercially available products (which can detect approximately 1 mL of blood) and comparable to a recently reported value of approximately 10 μL. In this study, we merge two technologies to develop a more practical skin-friendly sensor that can be applied for safe, stress-free blood leakage monitoring during hemodialysis

Rapid preparation of solution-processed InGaZnO thin films by microwave annealing and photoirradiation

We fabricated solution-processed indium–gallium–zinc oxide (IGZO) thin-film transistors (TFTs) by microwave (MW) annealing an IGZO precursor film followed by irradiating with vacuum ultraviolet (VUV) light. MW annealing allows more rapid heating of the precursor film than conventional annealing processes using a hot plate or electric oven and promotes the crystallization of IGZO. VUV irradiation was used to reduce the duration and temperature of the post-annealing step. Consequently, the IGZO TFTs fabricated through MW annealing for 5 min and VUV irradiation for 1 min exhibited an on/off current ratio of 108 and a field-effect mobility of 0.3 cm2 V−1 s−1. These results indicate that MW annealing and photoirradiation is an effective combination for annealing solution processed IGZO precursor films to prepare the semiconductor layers of TFTs

Reverse Offset Printing of Semidried Metal Acetylacetonate Layers and Its Application to a Solution-Processed IGZO TFT Fabrication

The submicrometer resolution printing of various metal acetylacetonate complex inks including Fe, V, Mn, Co, Ni, Zn, Zr, Mo, and In was enabled by a robust ink formulation scheme which adopted a ternary solvent system where solubility, surface wettability, and drying as well as absorption behavior on a polydimethylsiloxane sheet were optimized. Hydrogen plasma in heated conditions resulted in bombarded, resistive, or conductive state depending on the temperature and the metal species. With a conductivity-bestowed layer of MoO_<i>x</i> and a plasma-protecting layer of ZrO_<i>x</i> situated on the top of an IGZO layer, a solution-processed TFT exhibiting an average mobility of 0.17 cm²/(V s) is demonstrated

Metal-Enhanced Fluorescence Platforms Based on Plasmonic Ordered Copper Arrays: Wavelength Dependence of Quenching and Enhancement Effects

Ordered arrays of copper nanostructures were fabricated and modified with porphyrin molecules in order to evaluate fluorescence enhancement due to the localized surface plasmon resonance. The nanostructures were prepared by thermally depositing copper on the upper hemispheres of two-dimensional silica colloidal crystals. The wavelength at which the surface plasmon resonance of the nanostructures was generated was tuned to a longer wavelength than the interband transition region of copper (>590 nm) by controlling the diameter of the underlying silica particles. Immobilization of porphyrin monolayers onto the nanostructures was achieved <i>via</i> self-assembly of 16-mercaptohexadecanoic acid, which also suppressed the oxidation of the copper surface. The maximum fluorescence enhancement of porphyrin by a factor of 89.2 was achieved as compared with that on a planar Cu plate (CuP) due to the generation of the surface plasmon resonance. Furthermore, it was found that while the fluorescence from the porphyrin was quenched within the interband transition region, it was efficiently enhanced at longer wavelengths. It was demonstrated that the enhancement induced by the proximity of the fluorophore to the nanostructures was enough to overcome the highly efficient quenching effects of the metal. From these results, it is speculated that the surface plasmon resonance of copper has tremendous potential for practical use as high functional plasmonic sensor and devices