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Attention toward automated driving has recently increased. This has also increased the need to monitor drivers’ actions, such as finger touch/pressure sensing on the steering wheel. This study demonstrates an active signal-generating spacer-fabric-type continuous touch/pressure sensor comprising five yarn layers: surface-insulating cotton, upper conductive, monofilament spacer, lower conductive and bottom-insulating cotton yarn. The sensor actively generates signals, and the magnitude of the voltage output through a diode bridge and capacitor circuit determines if the fingers are ‘not touching’, ‘touching’, ‘pushing’ or ‘pushing hard’. This demonstrates that the proposed sensor can be operated as an active signal-generating touch/pressure sensor and can also detect ‘pushing hard’ actions. Furthermore, the active signal-generating operation originates from the electromagnetic waves emitted by electrical appliances and cables powered by a commercial power supply frequency in the environment. The proposed sensor will contribute to developing high-cushioning touch/pressure sensors with low power consumption and excellent air permeability that can be used in electric and autonomous vehicles.

This paper presents an experimental and numerical investigation of the internal flow in a Francis turbine draft tube previously designed for minimizing pressure fluctuations and energy losses in off-design conditions. The design of the draft tube geometry is based on an original approach combining Design of Experiments and steady/unsteady Computational Fluid Dynamics (CFD) simulations of the draft tube internal flow. The proposed method provides new insight on the influence of the draft tube geometry on the flow dynamic behaviour on one hand and enables the determination of a geometry promoting flow stability and hydraulic performance on another hand. CFD simulations of the internal flow in the final geometry showed promising results in terms of flow stability compared with the initial geometry designed by conventional CFD-aided methods. A reduced-scale model of the prototype machine featuring the final draft tube geometry is finally installed and tested in laboratory. Tests include performance and pressure fluctuations measurements over the complete operating range. The analysis of the results shows that the draft tube flow remains globally stable over the complete part-load range with pressure fluctuations amplitude lower than 1% of the net head. It is also shown that the dominant pressure component at the runner outlet in the draft tube cone is of synchronous nature. The physical mechanisms of excitation are finally highlighted by analysis of unsteady CFD simulation results.

Tactile sensors are widely used by the robotics industries over decades to measure force or pressure produced by external stimuli. Piezoelectric-based pressure sensors have intensively been investigated as promising candidates for tactile sensing applications. In contrast, piezoelectric-based pressure sensors are expensive due to their high cost of manufacturing and expensive base materials. Recently, an effect similar to the piezoelectric effect has been identified in non-piezoelectric polymers such as poly(d,l-lactic acid (PDLLA), poly(methyl methacrylate) (PMMA) and polystyrene. Hence investigations were conducted on alternative materials to find their suitability. In this article, we used inexpensive atactic polystyrene (aPS) as the base polymer and fabricated functional fibers using an electrospinning method. Fiber morphologies were studied using a field-emission scanning electron microscope and proposed a unique pressure sensor fabrication method. A fabricated pressure sensor was subjected to different pressures and corresponding electrical and mechanical characteristics were analyzed. An open circuit voltage of 3.1 V was generated at 19.9 kPa applied pressure, followed by an integral output charge (ΔQ), which was measured to calculate the average apparent piezoelectric constant dapp and was found to be 12.9 ± 1.8 pC N−1. A fabricated pressure sensor was attached to a commercially available robotic arm to mimic the tactile sensing.

Magnetic field effects on a radical ion pair have been studied to investigate the diffusion of the radical ions generated by a photoinduced electron transfer reaction in ionic liquids having short and long alkyl chains. The yield of an escaped radical ion was evaluated by using a nanosecond laser flash photolysis under various magnetic fields. The magnitude of the magnetic field effect on the yield of the escaped radical was linearly increased with increasing solvent viscosity. Such solvent viscosity dependence of the magnetic field effect can be explained with the solvent viscosity dependence of the escape rate of the radical ions from the pair. In the time window (>20 ns) of our measurements, the effect of long alkyl chain aggregation on the dynamics of the radical ions was not clearly observed.

An electroless metal plating method was used to form Pt shells on sub-micrometer-sized silica (SiO2) particles fabricated by a sol-gel method. The electroless metal plating method was comprised of three steps: (1) surface-modification of SiO2 particles with polyvinylpyrrolidone (PVP) (SiO2/PVP) or poly-diallyldimethylammonium chloride (PDADMAC) (SiO2/PDADMAC), (2) pre-deposition of Pt nuclei or Pt fine particles on the SiO2 particles by reducing Pt ions in the presence of SiO2/PVP particles (SiO2/PVP-Pt) or SiO2/PDADMAC particles (SiO2/PDADMAC-Pt), and (3) growth of the pre-deposited Pt by immersing the SiO2/PVP-Pt or SiO2/PDADMAC-Pt particles in a Pt-plating solution. The pre-deposition of Pt nanoparticles was successfully performed for the surface-modified SiO2 particles since the surface modification possibly strengthened the affinity between the SiO2 particle surfaces and Pt ions. The Pt nanoparticles were pre-deposited more uniformly in the case of PVP because the pre-deposition took place more slowly for the PVP, which provided uniform surface-modification followed by the uniform pre-deposition of Pt nanoparticles. The formation of Pt shells was successfully performed on the SiO2/PVP-Pt particles in the electroless metal plating process because Pt nuclei were generated by the reduction of H2PtCl6 and then further deposited on the Pt particle surfaces on the SiO2/PVP-Pt particles.

Electrospun polymer submicroscale fibers normally have flexible cylindrical waveguide geometries and can be produced with ultra-long and functional materials. Hence, they are promising building blocks for small optical devices. However, the propagation loss in the fibers is still higher than that in submicroscale polymer fibers produced by melt and solution drawing. In this study, thermal drawing of electrospun fibers was found to reduce their propagation loss. Fivefold thermal drawing of as-electrospun polymer fibers significantly reduced their diameters (e.g., from 1.121 μm to 0.497 μm) and propagation loss (e.g., from 16 dB cm−1 to 6.6 dB cm−1 at 521-nm wavelength). Because fluctuations in the fiber diameter significantly reduced after thermal drawing, the propagation loss reduction could be attributed to the reduced fluctuations in addition to the reduced density inhomogeneity in the fibers. These findings pave the way for low-loss electrospun fiber waveguides and their application in small optical devices.

Wet-electrospun (WES) polymer micron and submicron fibers are promising building blocks for small, flexible optical fiber devices, such as waveguides, sensors, and lasers. WES polymer fibers have an inherent cylindrical geometry similar to that of optical fibers and a relatively large aspect ratio. Furthermore, WES fibers can be produced using low-cost and low-energy manufacturing techniques with large-area fabrication and a large variety of materials. However, the high propagation loss in the fibers, which is normally on the order of tens or thousands of decibels per centimeter in the visible light region, has impeded the use of these fibers in optical fiber devices. Here, the origin of propagation losses is examined to develop a comprehensive and versatile approach to reduce these losses. The excess light scattering that occurs in fibers due to their inhomogeneous density is one of the primary factors in the propagation loss. To reduce this loss, the light transmission characteristics were investigated for single WES polymer fibers heated at different temperatures. The propagation loss was significantly reduced from 17.0 to 8.1 dB cm–1 at 533 nm wavelength, by heating the fibers above their glass transition temperature, 49.8 °C. In addition, systematic verification of the possible loss factors in the fibers confirmed that the propagation loss reduction could be attributed to the reduction of extrinsic excess scattering loss. Heating WES polymer fibers above their glass transition temperature is a versatile approach for reducing the propagation loss and should be applicable to a variety of WES fibers. This finding paves the way for low-loss WES fiber waveguides and their subsequent application in small, flexible optical fiber devices, including waveguides, sensors, and lasers.

Two passive plasmonic demultiplexers with multimode interferometer (MMI) based rectangular and bow-tie designs are demonstrated for 1.31- and 1.55-μm-band wavelength division multiplexing system operation in plasmonic circuits. These demultiplexers are designed using the finite-difference time-domain (FDTD) method and fabricated using complementary metal–oxide–semiconductor compatible processes. SiO2 films deposited on metal films are etched to form mesa structures by focused ion beam milling, and single-mode waveguides, MMIs, and bow-tie structures are then formed on the metal films. In the plasmonic circuits, 1.31- or 1.55-μm-wavelength surface plasmon polariton (SPP) signals can be distributed to each of the different demultiplexer outputs without any change in signal propagation speed. The SPP intensity distributions that are measured using a scanning near-field optical microscope agree well with the distributions that were calculated using the FDTD method. The insertion loss and crosstalk are then calculated for each demultiplexer. In the rectangular-type demultiplexer, the calculated values were less than 9.5 dB and –2.4 dB, and in the bow-tie-type demultiplexer, the corresponding values were 8.9 dB and less than –2.3 dB, respectively. These results demonstrate the applicability of the developed plasmonic demultiplexers to plasmonic circuits when monolithically integrated on a silicon substrate.

A variety of crystal structures is found in nature, not only equilibrium structures reflecting molecular structures, but also non-equilibrium structures which depend on the physicochemical conditions occurring during the crystal growth. In this paper, we focus on the dendrite structure of sodium chloride (NaCl) formed by the simple evaporation of an aqueous NaCl solution. The characteristics of the growth structures were measured as a function of the initial concentration of NaCl. In addition, the crystal growth process was measured using optical microscopy. As a result, the growth rate was not constant but was found to oscillate over time and synchronize with the wetting of the crystal. Our observations indicate that dendrite structures are more easily generated at higher initial concentrations. The detailed mechanism for dendrite pattern formation is still under investigation.

Electromechanically active submicron/micron polymer fibers are promising building blocks for biological/soft-robotic motion sensors and pressure sensors. In particular, mats of the fibers produced by electrospinning demonstrated distinct direct/converse electromechanical properties compared to those of films. Although several studies have demonstrated the direct electromechanical characteristics of the electromechanically active electrospun fiber mats, detailed investigation of the characteristics when the testing probe starts to contact the fiber mats, in addition to the effect on the preloading value, have not been reported. In this study, a sequential approaching/loading electromechanical testing technique has been proposed for a detailed investigation of the electromechanical properties of the fiber mats, in particular, near the contact between the testing electrode and the fiber mats. The results demonstrate that the preload and load values significantly affect the measured values of the apparent piezoelectric d constant (dapp). Therefore, careful determination of the applied preload and load values was a prerequisite for measuring the dapp of the very soft fiber mats. The present technique also demonstrates that the measured value of the capacitance of the fiber mat is significantly affected by the value of the applied load; therefore, a careful determination of the loading value is indispensable for measuring the capacitance of the fiber mats. The proposed technique can pave the way for a deep understanding of the direct electromechanical characteristics of a variety of significantly soft submicron/micron fiber mats and can aid the exploration of strategies to develop advanced biological/soft-robotic motion sensors and pressure sensors employing these mats.

Electromechanically active submicron/micron polymer fibers are promising components of wearable pressure sensors because they are mechanically flexible and lightweight. Recently, an as-electrospun microfiber mat comprising atactic polystyrene (aPS) demonstrated significantly high quasistatic direct electromechanical responses, although aPS films are not normally piezoelectric in nature. In this study, we investigated the quasistatic direct electromechanical properties of as-electrospun submicron/micron fiber mats composed of several polymers, namely poly(methyl methacrylate) (PMMA), aPS, poly(vinyl alcohol) (PVA), poly(D, l -lactic acid) (PDLLA), poly( l -lactic acid) (PLLA), and poly[(R)-3 hydroxybutyric acid] (PHB). As-electrospun PMMA, aPS, PDLLA, PLLA, and PHB fiber mats demonstrated significantly high direct electromechanical responses 22 h after fabrication, despite the nonpiezoelectric nature of PMMA, aPS, and PDLLA, whose films normally do not exhibit electromechanical responses. In contrast, the as-electrospun PVA fiber mat hardly showed any direct electromechanical response. We examined the surface potentials of these fiber mats, which revealed that the surface potential of the PVA fiber mat decayed rapidly and was essentially quenched within 2 h after fabrication, demonstrating that electrospinning forms polymer fibers with different abilities to retain charge and, as a consequence, different electromechanical responses. The direct electromechanical properties of the PMMA and aPS fiber mats were stable, even 30 d after fabrication, which is mainly attributable to the lower volume conductivities of these polymers. Selective discharging of real charges, including surface charges and space charges, through spraying with isopropanol mist revealed that the direct electromechanical responses of the fiber mats are due to real charges stored in the fiber mats through electrospinning. These fundamental findings provide novel material-choice opportunities for the development of large-area, flexible, lightweight, and inexpensive pressure sensors.

Real-time recording of the kinetics of systemically administered drugs in in vivo microenvironments may accelerate the development of effective medical therapies. However, conventional methods require considerable analyte quantities, have low sampling rates and do not address how drug kinetics correlate with target function over time. Here, we describe the development and application of a drug-sensing system consisting of a glass microelectrode and a microsensor composed of boron-doped diamond with a tip of around 40 μm in diameter. We show that, in the guinea pig cochlea, the system can measure—simultaneously and in real time—changes in the concentration of bumetanide (a diuretic that is ototoxic but applicable to epilepsy treatment) and the endocochlear potential underlying hearing. In the rat brain, we tracked the kinetics of the drug and the local field potentials representing neuronal activity. We also show that the actions of the antiepileptic drug lamotrigine and the anticancer reagent doxorubicin can be monitored in vivo. Our microsensing system offers the potential to detect pharmacological and physiological responses that might otherwise remain undetected. A system consisting of a glass microelectrode and a boron-doped diamond microsensor can simultaneously track, in rat brains and in the guinea pig cochlea, the local real-time kinetics of injected drugs and the resulting electrophysiological activity.

We have analyzed the propagation behavior of 1.31-and 1.55-μm-wavelength-band surface plasmon polaritons (SPPs) for three simple Si-based plasmonic waveguides: the Au stripe waveguide, the SiO2 stripe waveguide, and the Au/SiO2 stripe waveguide on a Si substrate. The SPP propagation length in the waveguide varied depending on the waveguide structure and propagation lengths for waveguides with different structural parameters are summarized. The energy that was required for SPP detection after propagation along the waveguides for the 1.31- and 1.55-μm-wavelength bands was calculated for intensity-modulation direct-detection and heterodyne frequency-shift keying systems. The results demonstrate that SPPs can propagate with lower energy consumption than conventional electric wiring below a specific interconnect length. A wavelength-selective structure for SPPs that comprised nano-slits in an Au film on an Si substrate was fabricated. The device can selectively detect 1.31-μm-wavelength SPPs as electrical signals and transmit 1.55-μm-wavelength SPPs. Experimental photoresponses and transmittances were measured and compared with calculated results. Magnitude correlation of the measured and calculated photoresponses and transmittances showed good agreement. Evaluation of the SPP propagation behavior and the wavelength-selective structure are important considerations for the development of optoelectronic integrated circuits that use SPPs and electrons as signal carriers.

Dye-doped, submicron fiber waveguides composed of hole- and electron-transport materials, with a mean diameter of 480–660 nm were fabricated and their waveguiding properties studied. Dye emitted photoluminescence was guided in the fibers and the loss coefficient was calculated to be 1.2 × 10−3–3.9 × 10−3 μm−1 at a wavelength of 540 nm, which is lower than previously reported for optically active polymer submicron fibers. Finally, a feasible method to couple the fibers with counter electrodes is presented using phase segregation of an insulating polymer. These submicron fiber waveguides, composed of optically and electrically active materials, can be used to produce OLED-waveguides, which are applicable in the fields of textile optoelectronics, lab-on-a-chip, and optogenetics.

We demonstrate a novel wavelength-division multiplexing 1.31- and 1.55-μm-wavelength-band plasmonic multiplexer that employs the multimode interference effect. The multiplexer comprises SiO 2 stripes on a Au film and was fabricated using a process compatible with standard complementary metal-oxide-semiconductor processing techniques. To suppress the return loss, tapered structures were introduced to the multiplexer. Finite-difference time-domain simulations indicate that losses were reduced by 12 dB. The multiplexing operation was confirmed with a scanning near-field optical microscopy. The reflection effect (return loss) appeared as an interference fringe of incident and reflecting surface plasmons in the multimode waveguide. The interference fringe disappeared in the multiplexer employing the taper structure.

This paper presents a plasmonic circuit that has been monolithically integrated with electronic devices on a silicon substrate and then discusses the concept behind this circuit. To form the proposed circuit, two plasmonic waveguides and a detector are integrated with metal–oxide–semiconductor field-effect transistors (MOSFETs) on the substrate. In the circuit, intensity signals or coherent plasmonic signals are generated by coherent light at an operating wavelength at which silicon is transparent, and these signals propagate along the waveguides before they are converted into electrical signals by the detector. These electrical intensity and coherent signals then drive the MOSFETs during both DC and AC operation. The measured performances of the devices indicate that surface plasmon polaritons propagate on the metal surface at the speed of light and drive the electronic devices without any absorption in the silicon.

To sense hydrophilic anions in protic solvents, we fabricated polymethylmethacrylate (PMMA) nanofibers incorporating 4-nitrophenyl azo thiourea polymer as a chromoionophore. When methanol solutions containing anions contacted the PMMA nanofiber, a bathochromic shift from 386 nm was observed in the absorption maximum of the chromoionophore. This spectral change is due to hydrogen bond formation between the urea moiety of the thiourea-based polymer and anions penetrating the nanofiber. This spectral change was not observed in PMMA film incorporating the same anion sensor, and the difference is attributed to the much larger specific surface area of the nanofiber compared to the film. As a result, many anions could react with the anion-sensing polymers in the nanofiber and induce a large spectral response.

Polymer electrolyte fuel cells (PEFC) is energy converter with high efficiency and operates at low temperatures of 80oC, thus it gains attention as an automotive power plant. Stainless steels, which could be used as a PEFC bipolar plate material, can be made very thin1), and has the advantage that the power density of a single cell can be improved. However, it has been reported that the proton conductivity of the electrolyte membrane decreases due to the dissolved iron and chromium ions from the polarized stainless steels due to the current fluctuation during PEFC operation2-3). In this study, the surface treatment method of stainless steels for improving the corrosion resistance was proposed and the electrochemical properties were evaluated. The anodic polarization curve of stainless steels was measured by a three-electrode system using an electrochemical measurement system (HZ-7000, Hokuto). The working electrode was SUS316L with various surface treatments. A platinum wire and a silver-silver chloride electrode were used for counter and reference electrodes. The electrolyte was 1.0 M H2SO4 (pH 3) containing 1 ppm NaCl and 3ppm NaF. and this electrolyte is defined as a PEFC simulation environment. The measurement temperature was 80oC, the potential scan range was from the immersion potential to 1.5 V vs. SSE, and the potential scan rate was 100 mV min-1. Three types of stainless steels were used for the working electrode: I. SUS316L, II. SUS316L treated by chemical conversion (CC SUS316L), and III. SUS316L anodized in electrolyte for chemical conversion (anodized SUS316L). The electrolyte for chemical conversion was a 1:1 mixture of 0.1 M Na2WO4 aqueous solution and 0.1 M Na2MoO4 aqueous solution, and the temperature of electrolyte for chemical conversion was 25oC. In the treatment II, SUS316L was immersed in the electrolyte for chemical conversion for 5 min. In the treatment III, SUS316L was polarized in a electrolyte for chemical conversion at an applied potential of 1.0 V vs. SSE for 5 min. Figure 1 displays the anodic polarization curves of SUS316L with various surface treatments in the simulated PEFC environment. The anodic polarization curve of SUS316L showed passive range from the immersion potential -0.3 V vs. SSE to 0.7 V vs. SSE and small current peak due to the formation of the passive film around 0 V vs. SSE. In the transpassive region at the potential nobler than 0.7 V vs. SSE, the current density region increased sharply. At potentials nobler than 1.3 V vs. SSE, the current density increased sharply due to electrolysis of water. The shape of the anodic polarization curve of the CC SUS316L was almost the same as that of the SUS316L, however, the polarization curve showed a small current density in the passive and transpassive regions. No passive region was observed in polarization curve of the anodized SUS316L. And compared to SUS316L and CC coating SUS316L, the immersion potential shifted to noble and the current density in the transpassive region decreased. References 1) F, Barbir. “PEM Fuel Cells Theory and Practice”, Academic Press, 4 (2005), 100, 101. 2) A. Pozio, R. F. Silva, M. De Francesco, L. Giorgi, Electrochim. Acta, 48 (2003), 1543-1549. 3) H. Wang, J. A. Turner, J Power Sources, 183 (2008), 576-580. Figure 1

Background Cancer stem cells (CSCs) have enhanced mechanisms of protection from oxidative stress. A variant form of CD44 (CD44v), a major CSC marker, was shown to interact with xCT, a subunit of cystine–glutamate transporter, which maintains high levels of intracellular reduced glutathione (GSH) which defend the cell against oxidative stress. Sulfasalazine (SSZ) is an inhibitor of xCT and was shown to suppress the survival of CD44v-positive stem-like cancer cells both in vitro and in vivo. To find the dose of SSZ which can safely reduce the population of CD44v-positive cells in tumors, a dose-escalation study in patients with advanced gastric cancer was conducted.

A poly-DL-lactide (PLA) fiber film was prepared using the electrospinning method. This film consisted of randomly oriented PLA nanofibers. Consequently, it had sponge-like structure and was quite soft compared to PLA films prepared by spin coating. The average diameter of the fibers and the density of the film were 730 nm and 20%, respectively. By applying a voltage, the PLA film was subjected to electric-field-induced strain: expansion and compression in the thickness direction. When a voltage of −200 V was applied to the film, its thickness shrank from 13.5 μm to 10.0 μm (a 26% reduction). Electric-field-induced strain can occur via two different mechanisms: The first is electrostrictive behavior. That is, in a highly electric field region, a change of film thickness occurs (compression only) from the electrostatic force between electrodes. The second mechanism is piezoelectric-like behavior that occurs in racemic PLA, wherein a PLA nanofiber is expanded and compressed by applying positive and negative voltage. Such piezoelectric-like behavior was not observed in spin-coated PLA films.

Dye-doped submicron poly(N-vinylcarbazole) fibers having mean diameters of 290–430 nm were fabricated via electrospinning and their waveguiding properties were investigated. The middle of each fiber's length was excited with UV light and guided photoluminescence (PL) was measured at the end of each of the fibers for different propagation lengths. The spectral shapes of the guided PL differed depending on the fiber diameter because of leakage of light into the substrate. We propose a model that reproduces the PL attenuation with increasing propagation lengths and includes the temporal PL decay due to photobleaching and the size of the excitation area. The calculated propagation loss coefficient in the fibers was 6.3 × 10−3−1.4 × 10−1 µm−1 with λ = 430–500 nm. The propagation loss was inherent in the fiber itself because the re-absorption loss coefficient of the doped dye was

Flexible and lightweight pressure sensors have attracted tremendous attention as a promising component of wearable biological motion sensors and artificial electronic skins. Here, the electromechanical response of as-electrospun fiber mats composed of a commodity polymer, atactic polystyrene, which can be applied in low-cost/large-area, flexible, and lightweight pressure sensors is demonstrated. The fiber mat demonstrates a significantly high apparent converse piezoelectric constant of >30 000 pm V-1 under static measurement and ≈13 000 pm V-1 even at a high frequency of 1 kHz. The first theoretical model to explain the unique electromechanical response is constructed, which reveals that the softness and moderate charge of the fiber mat are the reasons for the significantly high electromechanical response. Further, apparent piezoelectric constants obtained by direct measurement are lower than those obtained by the converse measurement, which is attributed to the densification and hardening of the fiber mat due to prepressure applied in direct measurement. These findings are likely to serve as a milestone for the development of large-area, flexible, and lightweight pressure sensors at low cost, as well as highly movable actuators like optical modulators without a substantial mechanical load.

Dual-gate pressure sensors consist of a piezoelectric polyvinylidene fluoride and trifluoroethylene P(VDF-TrFE) sensor and a low-voltage OFET read-out element. The pressure-induced voltage from the piezoelectric layer depletes charge carriers accumulated in the channel of the OFET, causing a shift in threshold voltage. By a quantitative analysis of results obtained from both the dual-gate organic pressure sensor and a conventional dual-gate OFET, we show that the piezoelectric constant of the sensing layer is estimated to be 72 pC/N. By comparing this value with that measured directly with piezoelectric measurement system, we concluded that the operation mechanism of the dual-gate pressure sensor was due to the piezoelectric behavior of the P(VDF-TrFE) layer.

Micrometer/submicrometer electromechanical polymer fibers are promising components for wearable pressure sensors and energy harvesters because of their high mechanical flexibility, low weight, and excellent breathability. Recently, the excellent electromechanical properties of mats of the as-electrospun micrometer/submicrometer polymer fibers have been reported; however, these devices have a contacting electrode/fiber mat/electrode structure. In this study, the electrical output properties of an as-electrospun polystyrene fiber mat with one electrode not in contact and/or in contact with the fiber mat were theoretically and experimentally investigated. The electric charges were output when the uncontacted electrode approached the fiber mat, and the amount of electric charges increased monotonically during the approach even after the electrode contacted the fiber mat and indented. The amount of electric charges was determined using theoretical functions. At the maximum displacement of the electrode, the average maximum output voltage had an absolute value of 2.28 ± 0.04 V when using the electrode with an area of 5.0 × 10−5 m2, a load of 10.1 MΩ, and a displacement time of approximately 15 ms. These experimental and theoretical findings can pave the way for the development of soft, lightweight, and breathable wearable pressure sensors and energy harvesters from a variety of materials and unique structures.

This paper presents a feasibility study of optical interconnections using surface plasmon polaritons (SPPs) as coherent carrier waves in a silicon-based electrical circuit. A gold film plasmonic waveguide and a gold/silicon Schottky-type plasmonic detector were monolithically integrated with an electrical circuit based on metal–oxide–semiconductor field-effect transistors on a silicon substrate. A 1550-nm-band laser source was used for SPP excitation, and the photocurrent generated by the plasmonic detector was amplified 16 000 times by the monolithically integrated electrical circuit after SPPs carrying the optical intensity signal propagated over the gold film surface for a distance of 100 μm. The integrated circuit detected an optical beat signal by using a delayed self-homodyne technique, thus demonstrating that SPPs can be used as coherent carrier waves in the circuit. Additionally, optical amplitude- and frequency-modulated signal transmission in a gold film plasmonic waveguide and optical heterodyne detection by amplification of the signal intensity in a gold/silicon Schottky-type plasmonic detector were also demonstrated.

Using metal plasmonic waveguides as transmission lines for optical signals and an electrical bias is shown to be feasible in Si-based devices with a separation gap formed between the waveguide and Au/Si Schottky-barrier diode (SBD). Optical signal transmission is confirmed by calculating the radiation pattern from the waveguide edge and measuring the photocurrent detected at the SBD. From a finite-difference time-domain simulation, the radiation pattern from the waveguide edge is represented as an interference fringe. The simulation result for the separation-length dependence of the detected photocurrent at the SBD corresponds well with experiment. Moreover, the intensity-modulated optical signal at 10 MHz is also observed across the 3-μm-length separation gap. The electrical bias separation is confirmed by applying a bias voltage between the waveguide and the Si substrate and generating a bias current through the waveguide. The detected photocurrent at the SBD barely increased with changing bias voltage and was clearly smaller than that under changes in optical intensity. In addition, electrical current produced no influence on the surface-plasmon signal on the waveguide.

A plasmonic integrated circuit configuration comprising plasmonic and electronic components is presented and the feasibility for high-speed signal processing applications is discussed. In integrated circuits, plasmonic signals transmit data at high transfer rates with light velocity. Plasmonic and electronic components such as wavelength-divisionmultiplexing (WDM) networks comprising metal wires, plasmonic multiplexers/demultiplexers, and crossing metal wires are connected via plasmonic waveguides on the nanometer or micrometer scales. To merge plasmonic and electronic components, several types of plasmonic components were developed. To ensure that the plasmonic components could be easily fabricated and monolithically integrated onto a silicon substrate using silicon complementary metal-oxide-semiconductor (CMOS)-compatible processes, the components were fabricated on a Si substrate and made from silicon, silicon oxides, and metal; no other materials were used in the fabrication. The plasmonic components operated in the 1300- and 1550-nm-wavelength bands, which are typically employed in optical fiber communication systems. The plasmonic logic circuits were formed by patterning a silicon oxide film on a metal film, and the operation as a half adder was confirmed. The computed plasmonic signals can propagate through the plasmonic WDM networks and be connected to electronic integrated circuits at high data-transfer rates.

Magnetic field effects (MFEs) on photoinduced electron transfer reaction between benzophenone (BP) and 1,4-diazabicyclo [2.2.2] octane in an ionic liquid (IL) of N,N,N-trimethyl-N-propylammonium bis(trifluoromethanesulfonyl) amide were studied by a nanosecond laser flash photolysis technique. The escape yield of the benzophenone radical anion (BP•–) was increased with increasing magnetic field strength (B) of 0 T < B ≤ 0.1 T and almost saturated at 0.1 T < B ≤ 1.7 T. The observed MFEs were explained by the hyperfine coupling mechanism (HFCM) and the relaxation mechanism (RM). The large MFEs indicate the nanometer-scaled cage effects on the diffusion of the radical ion pairs (RIP) generated by the photoinduced electron transfer reaction in TMPA TFSA. The cage lifetime for the RIP was estimated to be 170 ns, which is much longer than that previously reported for the neutral radical pairs (

An electroless metal plating method was used to form Pt shells on sub-micrometer-sized titania particles fabricated by a sol–gel method. The electroless metal plating method comprised three steps: (1) surface-modification of titania particles with poly(diallyldimethylammonium chloride) (PDADMAC) (TiO 2 –PDADMAC), (2) pre-deposition of Pt nuclei or Pt fine particles on the titania particles by reducing Pt ions in the presence of TiO 2 –PDADMAC particles (TiO 2 –Pt) and (3) growth of the pre-deposited Pt by immersing the TiO 2 –Pt particles in a Pt-plating solution. TEM observation and X-ray diffractometry revealed that surface modification with PDADMAC promoted the pre-deposition of Pt and that crystalline Pt shells with a thickness of approximately 25 nm were successfully produced on the titania particles using initial concentrations of 0.8 × 10 −3 M TiO 2 and 0.375 × 10 −3 M Pt in the Pt-plating solution.