Water strider inspires new testing method of ultra-thin films on water surfaces

Drawing inspiration from the water strider, researchers developed a new method of measuring the mechanical properties of ultra-thin films on water surfaces.

Article  |  Spring 2014

A joint research team of Professor Taek-Soo Kim from KAIST’s Department of Mechanical Engineering and Dr. Seung-Min Hyun of the Nano-mechanics Laboratory of the Korea Institute of Machinery and Materials has developed a new method to evaluate the mechanical properties of ultra-thin films using the characteristics of water surfaces.

The research findings have been posted in the online edition of Nature Communications on October 3^rd, 2013. The technology can obtain accurate results by directly measuring the mechanical properties, such as the strength and elasticity, of ultra-thin films. Experts in academia and industry expects the simplicity of the technology to present a new paradigm in the evaluation of the mechanical properties of ultra-thin films.

The evaluation of the mechanical properties of ultra-thin films is essential not only in predicting the reliability of semiconductors and displays, but also in finding new phenomena in the nanoworld. However, mechanical strength was difficult to assess since testing necessitates objects falling to the ground to measure their strength and nanofilms can easily break in the process.

The research team observed insects such as water striders freely floating on the water surface. The team used the properties of water, namely,  large surface tension and low viscosity, to float a 55nm-thick gold film to successfully measure its mechanical properties without damaging it. The technology could be used to measure the mechanical properties of not only various types of nanofilms but also films only a few nm thick.

Professor Taek-Soo Kim explained, “We effectively performed an evaluation of the mechanical characteristics of ultra-thin films, which was difficult in the past, by developing a new strength test using the properties of water. The team plans to discover the mechanical properties of 2D nanofilms, such as graphene, that could not have been measured with the existing strength test methods.”

by H. L. Yoon, KAIST News Office