Graphene Electrode Enabling Electrochromic Approaches for Daylight-Dimming Applications.

For environmental reason, buildings increasingly install smart windows, which can dim incoming daylight based on active electrochromic devices (ECDs). In this work, multi-layered graphene (MLG) was investigated as an ECD window electrode, to minimize carbon dioxide (CO) emissions by decreasing the electricity consumption for building space cooling and heating and as an alternative to the transparent conductor tin-doped indium oxide (ITO) in order to decrease dependence on it. Various MLG electrodes with different numbers of graphene layers were prepared with environmentally friendly poly(3,4-ethylenedioxythiophene):poly(styrene-sulfonate) (PEDOT:PSS) to produce ECD cells.

Highly conductive and environmentally stable gold/graphene yarns for flexible and wearable electronics.

Here, we fabricated high-performance gold/graphene yarns through a facile method by the electroless deposition of gold nanoparticles onto the surface of graphene yarns. The gold/graphene yarns are fabricated using a completely solution-based process that can be scaled up for practical applications. They possess high electrical conductivity (2.

Design and Fabrication of Integrated Fabry-Perot Type Color Reflector for Reflective Displays.

A Fabry-Perot type integrated color reflector, with red/blue/green colors as subpixels, was designed and fabricated with Si substrate. Ag films were used as reflective mirror layers, SiO2 films were used as Fabry-Perot cavity layers and W films were used as partially reflective layers for the cavity. To minimize the effects of the thickness variation of the oxide cavity layers, the structure of the color reflector was optimized, and the differential deposition scheme was devised and applied in the fabrication process.

Size and surface modification effects on the pH response of Si nanowire field-effect transistors.

We investigated the effects of Si nanowire (SiNW) dimensions and their surface modifications on the pH-dependent electronic transport characteristics of SiNW Electrolyte-insulator-Semiconductor Field-Effect Transistors (EISFETs). The threshold voltages, Vth's, of all devices were extracted from the Id-Vg characteristics with Vg applied to the reference electrode immersed in different pH solutions, and their pH-dependences were analyzed for various devices. We found that our devices produce the systematic pH-dependence of Vth with respect to the SiNW's length and show significant changes in a linear pH region and a pH sensitivity upon the Si surface modifications.

Magnetically-actuated blood filter unit attachable to pre-made biochips.

We present a novel blood filter unit that is designed to separate blood plasma from whole blood by simple magnetic actuation. A non-diluted blood sample is dropped into the filter unit and magnetic attraction is applied to squeeze out only blood plasma while blood particles are filtered by membranes stacked in the filter unit. The new filter device yields good filtering performance with nearly perfect filtering efficiency (∼99.

Detection of uncharged or feebly charged small molecules by field-effect transistor biosensors.

This paper describes a new technique for the detection of uncharged or feebly charged small molecules (<400Da) using Si field-effect transistor (FET) biosensors that are signal-enhanced by gold nanoparticle (NP) charges under dry measurement conditions. NP charges are quickly induced by a chemical deposition (that is, Au deposition) and the indirect competitive immunogold assay, and strongly enhance the electrical signals of the FET biosensors. For the validation of signal enhancement of FET biosensors based on NP charges and detection of uncharged or feebly charged small molecules, mycotoxins (MTXs) of aflatoxin-B1 (AFB1), zearalenone (ZEN), and ochratoxin-A (OTA) were used as target molecules.

Toxin detection by Si photosensitive biosensors with a new measurement scheme.

We propose a new type of photosensitive biosensor with a CMOS compatible Si photodiode integrated circuit, for the high-sensitive detection of small mycotoxin molecules requiring competitive assay approach. In this work, a photodiode is connected to the gate of a field effect transistor (FET) so that the open circuit voltage (V(OC)) of the illuminated photodiode is transferred into the drain/source current (I(DS)) of the FET. The sensing scheme employs competitive binding of toxin molecules (within the sample solution) and toxin-BSA conjugates (immobilized on the photodiode surface) with Au-nanoparticle-labeled antibodies, followed by silver enhancement to generate opaque structures on the photodiode surface.

Response to cardiac markers in human serum analyzed by guided-mode resonance biosensor.

Cardiac markers in human serum with concentrations less than 0.1 ng/mL were analyzed by use of a guided-mode resonance (GMR) biosensor. Cardiac troponin I (cTnI), creatine kinase MB (CK-MB), and myoglobin (MYO) were monitored in the serum of both patients and healthy controls.

Fabrication of anionic sulfate-functionalized nanoparticles as an immunosensor by protein immobilization.

Anionic sulfate (SO(4)(-))-functionalized polystyrene (PS) nanoparticles were prepared by the thermal decomposition of potassium persulfate (KPS) in the presence of sodium tetraborate via emulsion polymerization. The presence of a SO(4)(-) group at a solid/liquid interface of a particle surface was confirmed by a zeta potential value of -40.6 mV as well as the shifting of S 2p spectra toward a lower-binding-energy region around 162.

Direct label-free electrical immunodetection in human serum using a flow-through-apparatus approach with integrated field-effect transistors.

In order to identify changes in the levels of key proteins in response to the onset or development of a disease, the research fields of proteomics and genomics seek to develop new biomarkers. Specifically, simple and fast biomarker screens have a central role in many areas of healthcare, including disease diagnosis and drug discovery. Biologically modified field-effect transistor (BioFET) is one of the most attractive approaches because of the on-chip integration of the sensor array, fast response, high reliability and low-cost mass production.

Control of channel doping concentration for enhancing the sensitivity of 'top-down' fabricated Si nanochannel FET biosensors.

The sensitivity of 'top-down' fabricated Si nanochannel field effect transistor (FET) biosensors has been analyzed quantitatively, as a function of the channel width and doping concentration. We have fabricated 130-, 150-, and 220 nm-wide Si FET channels with 40 nm-thick p-type silicon-on-insulator (SOI) layers doped at 8 x 10(17) and 2 x 10(18) cm(-3), and characterized their sensitivity in response to the variation of surface charges as hydrogen ion sensors within buffer solutions of various pH levels. Within the range of channel width and doping concentration investigated, the pH sensitivity of Si channels is enhanced much more effectively by decreasing the doping concentration than by reducing the channel width, which suggests a practical strategy for achieving high sensitivity with less effort than to reduce the channel width.

Enhanced protein immobilization efficiency on a TiO2 surface modified with a hydroxyl functional group.

An antibody immobilization was investigated using a self-assembled monolayer (SAM) over the highly refractive coatings with a SiO2, TiO2, or Si3N4 substrate. The immobilization was characterized by analyzing the hydrophilic properties of hydroxyl (OH) groups on surface coatings with contact angle (CA) measurements to enhance protein immobilization. The hydroxyl (OH) group was formed in greater amounts as the oxygen plasma exposure time was increased, which resulted in a large enhancement in antibody immobilization.

Shape transformation and relaxation dynamics of photoexcited TiO2/Ag nanocomposites.

The laser-induced sintering of TiO2 nanoparticles into larger nanospheres is accelerated by adsorbed silver particles. For the same weight fraction of silver, silver nanoparticles of 5 nm in diameter modify TiO2 nanoparticles more effectively than those of 1.5 nm do, suggesting that the photocatalysis of TiO2 nanoparticles as well as their stability is highly dependent on the sizes, the shapes, and the distribution of adsorbed metal nanoparticles.

Excited-state tautomerization dynamics of 7-hydroxyquinoline in beta-cyclodextrin.

The excited-state tautomerization dynamics of 7-hydroxyquinoline encapsulated in beta-cyclodextrin is compared with that in pure water by measuring isotope-dependent fluorescence kinetics as well as absorption and emission spectra. The normal species tautomerizes stepwise via forming anionic intermediate species in both systems. However, the enol-deprotonation time (40 ps in water) becomes as large as 170 ps whereas the imine-protonation time of the anionic intermediate (160 ps in water) becomes as short as 85 ps in beta-cyclodextrin.

Laser-induced mutual transposition of the core and the shell of a Au@Pt nanosphere.

The mutual transposition of the core and the shell of a Au@Pt core-shell nanosphere has been obtained by employing picosecond laser pulses to excite the surface-plasmon resonances of platinum. The thermalized energy of the plasmon resonances makes the core metal of the gold melt earlier than the shell metal of platinum because of melting temperature differences and causes the gold to soak out of the core to the surface of the nanosphere. A new reversed core/shell Pt@Au core-shell nanosphere is formed with further irradiation.