Yu Wins NSF Grant to Study the Perception and Use of Infrared Radiation by Insects

Nanfang Yu, assistant professor of applied physics in the Department of Applied Physics and Applied Mathematics, leads a team of researchers from Columbia and Harvard, who have won a $400k three-year grant from the National Science Foundation (NSF) Physics of Living Systems (PoLS) program. Their project, "Perception and Use of Infrared Radiation by Insects," aims to understand the physical mechanisms underlying the ability of insects to perceive infrared light and to learn engineering lessons that can be used to create novel infrared materials, devices, and systems.

Animals have evolved diverse strategies to perceive and utilize electromagnetic waves: deep sea fish have eyes that enable them to maneuver and prey in dark waters, beetles and butterflies create colors from nanostructures in the cuticle of their wings, honey bees can see and respond to ultraviolet signals, and fireflies use flash communication systems. Organs evolved for perceiving or controlling electromagnetic waves often surpass analogous man-made devices in both sophistication and efficiency. Understanding and harnessing natural design concepts deepens our knowledge of complex biological systems and inspires ideas for creating novel technologies.

The project will investigate some long-standing mysteries regarding the ability of insects to perceive and respond to infrared radiation, which has a wavelength ranging from 0.7 to 20 micrometers. While many studies have focused on the physical optics of living systems in the UV and visible spectral range, an understanding of the role of infrared light in the lives of insects and other animals is rather limited. A number of compelling examples support the hypothesis that insects can perceive and respond to broadband thermal infrared radiation with high sensitivity, or narrowband “fingerprint” infrared radiation with high specificity. The objective of the project is to understand the physical mechanisms underlying the ability of insects to perceive broadband or narrowband infrared radiation.

One model system the research team will investigate is the so-called “scent pads” on the wings of butterflies. In particular, the team will study the tribe of butterflies Eumaeini, which contains over 1200 species worldwide and 45% of which have been recorded to have scent pads on the wings. The scent pads in male butterflies are involved in the generation and dissemination of sex pheromones that influence the behavior of female butterflies. The team’s initial study discovered that the wing scales covering the scent pads have unique microstructures and show extremely broadband, close-to-unity absorption over almost the entire mid-infrared band from 2.6 to 16 micrometers. The team speculates that the extraordinary optical properties may help the butterflies control the temperature of scent pads. In particular, by exposing their wings to sun light, the butterflies can heat up the scent pads quickly to a temperature higher than that of the rest of the wing, and this could assist in releasing sex pheromones by thermal evaporation.  By shielding the wings from the sun, the temperature of the scent pads and patches could drop quickly due to efficient thermal radiative transfer via blackbody radiation. By repeatedly opening and closing its wings, a male butterfly may be able to release pulses of sex pheromones while preventing scent pad and patch cells from experiencing heat stress.

The butterflies are just one subject that the team will study. The scope of the work is multifold: to build a platform consisting of multidisciplinary techniques to identify infrared perception organs of insects and to analyze their optical properties; to study the interaction between infrared light and the microstructures of insects; and to develop strategies to manipulate insect behavior using infrared light and to prototype infrared detection devices based on biomimicry.

This program will provide a quantitative understanding of insects’ remarkable capabilities in sensingbroadband thermal radiation and narrowband fingerprint infrared radiation. Detailed studies of the mechanisms by which insect sensilla perceive and respond to signals in the infrared spectral range have not been carried out before. Infrared signals may play a critical and underappreciated role in a wide variety of insect behaviors, and a greater understanding of this phenomenon is likely to catalyze a new area of research for the scientific community.The program will expand our understanding of how natural selection can shape exquisitely adapted behaviors and structures.

The team hopes to learn from this study useful engineering lessons that can be translated to device applications. For example, the study of butterfly wings could inspire us to develop ultra-thin and high-efficiency photovoltaic/thermophotovoltaic devices, planar bolometer arrays for infrared cameras, or even “invisibility cloaks” that render objects invisible under an infrared searchlight. This property could also be used to develop highly efficient thermal emitters and heat dissipation coatings.

The research team include physicists lead by Prof. Nanfang Yu from the Department of Applied Physics and Applied Mathematics at Columbia University and biologists lead by Prof. Naomi Pierce from the Department of Organismic and Evolutionary Biology and the Museum of Comparative Zoology at Harvard University. The two research groups will bring in their expertise in insect ecology, animal behavior, optical science, and electrical engineering to conduct this highly interdisciplinary research.

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