Numerical Analysis of Mode Coupling in Multimode Graded Index Optical Fibers with Bending

doi:10.18494/sam.2015.1052

Abstract

Highlights

The rapid advance of micro-electromechanical systems and semiconductor engineering in recent years has enabled the development of ever-smaller electronic components, which has led to a marked increase in the production of wearable devices
Most wearable devices are powered by batteries, but as such devices become smaller, the feasibility of using conventional batteries comes into question
Unlike conventional piezoelectric ceramics, which are extremely brittle and difficult to produce, polymeric piezoelectric nanofibers are inexpensive and have excellent flexibility and biocompatibility.[1] compared with piezoelectric films, piezoelectric polymers are more efficient in electromechanical energy conversion.[2]

Summary

Introduction

The rapid advance of micro-electromechanical systems and semiconductor engineering in recent years has enabled the development of ever-smaller electronic components, which has led to a marked increase in the production of wearable devices. Because of the growing demand for wireless devices and continuous sensing systems, Wang and Song used zinc oxide to fabricate piezoelectric nanowires for self-powered piezoelectric nanogenerators.[3] They first employed the vapor–liquid–solid method to produce zinc oxide nanowire arrays—approximately 0.2−0.5 μm in length and 100−800 nm in diameter—to convert mechanical energy into electrical energy They used Kevlar fibers as a base to grow ZnO nanowire arrays approximately 3.5 μm in length and 50−200 nm in diameter; the nanowire arrays relied on the friction between fibers to generate a power output of 20−80 mW/m2, thereby developing prototype power-generating garments.[4] One year later, they fixed ZnO nanofibers (100−500 μm in length and 100−800 nm in diameter) on a flexible substrate that could be worn on a finger, and this device was able to generate electricity (~25 mV and 150 pA) through the strain induced by the curling of the finger.[5] Because the vapor–liquid–solid method is difficult to apply to produce nanowires greater than 50 μm in length, electrospinning techniques have been proposed as an alternative for the production of piezoelectric nanofibers. The purpose of the experiment was twofold: [1] to observe how—after fixing the source of strain to ensure the input of the direct piezoelectric effects was on the same basis—the different electrode parameters affected the voltage output of the sensing element, and [2] to design and appraise a sensing module based on the piezoelectric sensing element

Electrode design

Sensing element

Experiment and Discussion

Findings

Conclusions