Portable Human Motion Detection Devices by Sponge-like Piezoresistive Materials

• Main Authors: Chia-Han Hsieh, 謝佳翰
• Other Authors: Wei-Ssu Liao
• Format: Others
• Language: zh-TW
• Published: 2019
• Online Access: http://ndltd.ncl.edu.tw/handle/maae92

碩士 === 國立臺灣大學 === 化學研究所 === 107 === Human motion devices made by piezoresistive sponges have attracted attention from many research groups over the past few years. Polymer sponges used as substrates or templates possess merits such as better mechanical properties include being flexible, stretchable, compressible, and light-weight. However, several main bottlenecks occur even after vigorous developments, e.g. lack of combination between substrate materials and conductive materials, complicated fabrication processes that lead to higher cost, and contradiction between sensitivity and detection range. Herein, we change the way of connecting the sponge and the copper electrode, using micro copper wires to create the micro-cylinder structure on the electrode to replace the conventional silver paste. Cylinder structures create gaps at the interface between two surfaces and increase the initial system resistance, raising device sensitivity and applicable pressure ranges. Comparing two melamine/PEDOT:PSS sponges with the same fabrication process, but one connected with silver paste and the other with our cylinder electrode, the system with cylinder electrode shows a 65-fold increment on gauge factor at 10% strain. This phenomenon is also present on other devices fabricated with two other piezoresistive sponge types: polyurethane/PEDOT:PSS and melamine/CNTs. Based on this observation, we design a portable human motion detection device. Innovations include the bottom cell substitute for power supply and signal recording system replacement by LED. Signals induced by different amount of pressure can be distinguished by naked eyes due to the high sensitivity of our cylinder structured piezoresistive sponge with the property of low power consumption. Our study provides a novel, simple, low-cost and visual strategy to tackle the issues of piezoresistive material sensitivity, pressure detection range, and portable capability.