World’s first biomimetic color-changing humidity sensor
Professors Lee Seung-yop and Park Jeong-yeol (Sogang University’s School of Mechanical Engineering) have developed a humidity sensor that requires no power supply or electronic circuitry. The design was inspired by the Hercules beetle of South America which is light green in low humidity but turns black in high humidity. The researchers were able to develop a 275-nanometer structure that mimicked the beetle's skin. Lee believes the concept could be applied to chemical sensors as well.
In addition to applying what they had learned about the structure of the beetle's skin, Lee and Park tried to emulate how nature solves problems. They relied on information and structure to achieve what traditional engineering would accomplish through energy and complex circuitry.
Additional links:
- Biologically inspired humidity sensor based on three-dimensional photonic crystals - paper by Kim, Moon, Lee and Park in Appl. Phys. Lett. 97, 103701 (2010); doi:10.1063/1.3486115 (3 pages)
- Humidity changes exoskeleton color: Hercules beetle - Ask Nature - principles, applications, experts and references
- Diffractive hygrochromic effect in the cuticle of the hercules bettle Dynastes hercules - paper by Rassart, Colomer, Tabarrant and Vigneron in New J. Phys. 10 033014 (2008); doi: 10.1088/1367-2630/10/3/033014
- Physiological colour change in the elytra of the hercules beetle Dynastes hercules - paper by Hinton and Jarman in Journal of Insect Physiology; Volume 19, Issue 3, March 1973, Pages 533-539, 541-549; doi:10.1016/0022-1910(73)90064-4
- University of Kentucky Department of Entomology - Hercules Beetles - extensive description and further links
Image courtesy of KBS World.
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Comments
Background from Prof. Lee
I contacted Professor Lee to get the history behind the biomimetic humidity sensor. He had read the New Journal of Physics paper by Rassart, et. al. that analyzed how the Hercules beetle passively reacted to humidity, changing from khaki-green in dry conditions to black under high humidity levels. This inspired Lee and his team to look at humidity sensors and design a sensor based on the principles described in the paper.