Detection of Methanol Using a Soft Photonic Crystal Robot

Robots are currently employed in industrial sites and fields, including disaster rescue, medicine, security, and national defense. Conventional metal-based robots exert strong operating power due to rigid body construction with joints connected to actuators such as motors. However, they may have difficulty with flexible movements and can cause harm during malfunctions. Recently, ‘soft robots’ made of smooth and flexible materials have emerged, but they may be more difficult to control than metal-based robots.

Korea Institute of Science and Technology (KIST, President Seok Jin Yoon) announced that the research team composed of Dr. Dae-Yoon Kim of the Functional Composite Materials Research Center, Dr. Seung-Yeol Jeon of the Carbon Composite Materials Research Center, and Prof. Kwang-Un Jeong of the Department of Polymer-Nano Science and Technology at Jeonbuk National University (JBNU, President O Bong Yang) has succeeded in manufacturing a soft robot with a Janus structure, and developing a smart sensor for methanol detection. Excessive exposure to methanol may be fatal to humans and cause headaches, vomiting, dizziness, and visual disturbances. However, as methanol is more than 70% cheaper than ethanol, cases of misuse and abuse are increasing after COVID-19.

Inspired by the free motions of mollusks such as the octopus, the research team adopted a method of allowing the movements of the soft robot to react spontaneously to the surrounding environment rather than controlling it with precise computing. By patterning two types of flexible polymer films with different expandability, the soft robot was allowed to move naturally in the desired direction according to the surrounding environment. Its motions include bending, folding, and twisting. In addition, a helicoidal nanostructure found in insects, such as butterflies, was introduced into soft robots, resulting in photonic crystal properties that selectively reflect the light of various colors. When the soft robot moves due to changes in the surrounding environment, the user can easily recognize this through color changes.

The authors developed a sensor that can easily and quickly detect methanol contamination in water by applying the developed soft photonic crystal robot. The methanol detection sensor using the soft photonic crystal robot is economical because it can be reused many times. The robot does not require electricity to operate, so it can easily detect methanol in water in any location. Additionally, the circular polarization properties from the helicoidal nanostructure of the soft robot are difficult to forge and alter, so they are very effective in securing product reliability.

Dr. Dae-Yoon Kim of KIST said: “This research has significance in implementing soft robots in everyday life. In the future, when multi-stimulus responsive materials capable of promptly and simultaneously responding to various external stimuli are developed, soft robots will be widely commercialized.”

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KIST was established in 1966 as the first government-funded research institute in Korea. KIST now strives to solve national and social challenges and secure growth engines through leading and innovative research. For more information, please visit KIST’s website at https://eng.kist.re.kr/

This research was conducted with the support of the K-Lab program of KIST and the Young Researcher Program of NRF. The research findings were published in ‘Advanced Functional Materials’ and selected as the frontispiece and hot topic in the field of robotics.