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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.

A simple and low-loss metal/semiconductor surface plasmon polariton (SPP) device consisting of a SPP waveguide and a detector is studied theoretically and experimentally. We demonstrate a simple diffraction structure (a metal grating) where the SPP couples from the waveguide to the detector. The SPP can propagate without large losses at the air/Au interface, and this interface was used for SPP waveguiding. To convert the SPP into an electric signal using internal photoemission, the propagating SPP is coupled into the Au/Si interface by the diffraction structure. The propagation direction of the coupled SPP at the Au/Si interface depends on the slit pitch of the diffraction structure, and the direction can be controlled by adjusting the pitch. The slit pitch is also modeled using a diffraction grating equation, and the results show good agreement with those of simulations using the finite-difference time-domain method. When diffraction structures consisting of a multi-slit structure and a disk array are placed at the end of the waveguide, SPP coupling into the Au/Si interface is also observed. The photocurrents detected at the Au/Si interface are much larger when compared with that detected for the device without the diffraction structure (26 times for the multi-slit structure and 10 times for the disk array). From the polarization angle dependence of the detected photocurrent, we also confirmed that the photocurrent was caused by the SPP propagating at the air/Au interface.

In this contribution we show highly polarized photoluminescence (PL) from aligned polyethyleneoxide: polyphenylenevinylene derivative composite nanofibers. We demonstrate PL polarization ratios (parallel to perpendicular) greater than 13. This ratio is further increased (up to ∼25) by stretching the nanofibers. Stretching also results in an increase in conjugation length, fiber density, and PL lifetime. We argue that the effect of stretching is equivalent to applying a permanent and strong pressure. Our results open up the possibility for new optoelectronic devices and fundamental science studies based on polymer nanofibers.