Mechanical Auxetic-Structured Substrates with Negative Poisson’s Ratio

Recently, there has been a lot of research on flexible devices that form electrodes on flexible substrates, away from hard substrates. However, existing flexible devices were limited in commercialization because they had problems such as image distortion and degradation of electrodes due to the positive Poisson's ratio when the substrate is stretched. To solve this problem, we tried to minimize the mechanical deformation that occurs during stretching the substrate by producing a flexible substrate that has the characteristics of negative Poisson's ratio. The substrate uses a flexible substrate, and to realize the negative Poisson’s ratio, the flexible substrate was completed by making an auxetic structure frame composed of a relatively rigid material into the substrate. The result of our study is that by inserting the auxetic structure into the substrate, we can control the Poisson’s ratio so that it has a lower Poisson’s ratio than the original part of the substrate. As a result, we were able to obtain a flexible substrate with more than 15% horizontal extension and less than 0.2 Poisson’s ratio. In the future, the development of an integrated flexible device in combination with an auxetic structure with a negative Poisson’s ratio can contribute to the development of the ideal stretchable substrate. Furthermore, it is expected that our research will be applied to various fields such as flexible displays, wearable sensors, and flexible electronic devices.