A transparent conductive polymer-based strain-sensor array, designed especially for touch input sheets of flexible displays, was developed. A transparent conductive polymer, namely poly(3, 4-ethylenedioxythiophene):polystyrenesulfonate (PEDOT:PSS), was utilized owing to its strength under repeated mechanical bending. PEDOT:PSS strain sensors with a thickness of 130 nm exhibited light transmittance of 92%, which is the same as the transmittance of ITO electrodes widely used in flat panel displays. We demonstrated that the sensor array on a flexible sheet was able to sustain mechanical bending 300 times at a bending radius of 5 mm. The strain sensor shows a gauge factor of 5.2. The touch point on a flexible sheet could be detected from histograms of the outputs of the strain sensors when the sheet was pushed with an input force of 5 N. The touch input could be detected on the flexible sheet with a curved surface (radius of curvature of 20 mm). These results show that the developed transparent conductive polymer-based strain-sensor array is applicable to touch input sheets of mechanically bendable displays.

We describe the design and characterization of a heterogeneous 36-core, 3-mode fiber with 3 core types. Inter-core crosstalk for LP11 modes is estimated to be below -31 dB for 5.5 km propagation at a core pitch of 34 μm. Feasibility of 108 spatial / mode division multiplexed transmission is investigated using free-space multiplexing / demultiplexing technologies, 40wavelength division multiplexed, 25 GBaud, 93.4-Gb/s dualpolarization QPSK signals, and coherent detection with a sparse 6 × 6 MIMO equalizer. The total transmission capacity amount to 403.7 Tb/s. Index Terms-Space division multiplexing, multi-core fiber, mode division multiplexing, few-mode fiber, multiple-input multiple-output, coherent communication, optical fibers. 0733-8724 (c)

We demonstrate transmission of 368-WDM-38-core-3-mode × 24.5-GBaud 64-and 256-QAM signals over 13 km. Record data-rate and spectral-efficiency of 1158.7 b/s/Hz were enabled by a low DMD 38-core-3-mode fiber with high uniformity amongst cores.

We describe the design and characterization of a 3-type heterogeneous 36-core, 3-mode fiber with record spatial channel count and density and perform transmission measurements in all 108 spatial channels using 40x100GHz spaced 25GBaud DP-QPSK signals.

This paper reports on a microelectromechanical systems (MEMS)-based sensor for pulse wave measurement. The sensor consists of an air chamber with a thin membrane and a 300-nm thick piezoresistive cantilever placed inside the chamber. When the membrane of the chamber is in contact with the skin above a vessel of a subject, the pulse wave of the subject causes the membrane to deform, leading to a change in the chamber pressure. This pressure change results in bending of the cantilever and change in the resistance of the cantilever, hence the pulse wave of the subject can be measured by monitoring the resistance of the cantilever. In this paper, we report the sensor design and fabrication, and demonstrate the measurement of the pulse wave using the fabricated sensor. Finally, measurement of the pulse wave velocity (PWV) is demonstrated by simultaneously measuring pulse waves at two points using the two fabricated sensor devices. Furthermore, the effect of breath holding on PWV is investigated. We showed that the proposed sensor can be used to continuously measure the PWV for each pulse, which indicates the possibility of using the sensor for continuous blood pressure measurement.

This paper reports on a method to directly measure the contractile forces of cardiomyocytes using MEMS (micro electro mechanical systems)-based force sensors. The fabricated sensor chip consists of piezoresistive cantilevers that can measure contractile forces with high frequency (several tens of kHz) and high sensing resolution (less than 0.1 nN). Moreover, the proposed method does not require a complex observation system or image processing, which are necessary in conventional optical-based methods. This paper describes the design, fabrication, and evaluation of the proposed device and demonstrates the direct measurements of contractile forces of cardiomyocytes using the fabricated device.

This paper reports on a tactile sensor using piezoresistive beams for detection of the coefficient of static friction merely by pressing the sensor against an object. The sensor chip is composed of three pairs of piezoresistive beams arranged in parallel and embedded in an elastomer; this sensor is able to measure the vertical and lateral strains of the elastomer. The coefficient of static friction is estimated from the ratio of the fractional resistance changes corresponding to the sensing elements of vertical and lateral strains when the sensor is in contact with an object surface. We applied a normal force on the sensor surface through objects with coefficients of static friction ranging from 0.2 to 1.1. The fractional resistance changes corresponding to vertical and lateral strains were proportional to the applied force. Furthermore, the relationship between these responses changed according to the coefficients of static friction. The experimental result indicated the proposed sensor could determine the coefficient of static friction before a global slip occurs.

We report the resonant frequency measurement of few-layer (1-, 2-, and 3-layer) graphene (FLG) cantilevers by optical heterodyne interferometry. The micro-sized FLG cantilevers with and without the diamond-like carbon weights were fabricated using focused ion beam. The Young's modulus was able to be calculated from the measured resonant frequency. The calculated Young's modulus was larger than the literature data [1]. This result suggests that the overlapped structure of the FLG cantilever makes the structure rigid.