BGU researchers reveal how damselflies create vivid, saturated colors, inspiring sustainable alternatives to synthetic pigments.
Blue-tailed female damselfly Photo Credit: Ian Kirk
Scientists at Ben-Gurion University of the Negev (BGU) have uncovered for the first time the "ingenious" biological strategies that allow blue-tailed damselflies to produce strikingly vivid, angle-independent colors. The study, published in the Proceedings of the National Academy of Sciences (PNAS)(https://www.pnas.org/doi/10.1073/pnas.2527433123), provides a new blueprint for creating sustainable, highly saturated photonic materials that could replace toxic synthetic pigments in industries ranging from cosmetics to textiles.
Structural colors in nature are often produced by photonic glasses—randomly arranged nanospheres that scatter light. While efficient, these systems typically suffer from poor color saturation because slight variations in particle size (polydispersity) wash out the resulting hue.
The damselfly’s secret: structural dispersion
Prof. Benjamin A. Palmer | Photo: Dani Machlis/BGU
The research team, led by Prof. Benjamin A. Palmer and PhD studentTali Lemcoff from BGU’s Department of Chemistry, discovered that blue-tailed damselflies (Ischnura elegans) overcome these physical limitations using two elegant evolutionary solutions:
Self-Correcting Particles: To keep the color sharp, damselflies ensure that as spheres get larger, their density (refractive index) drops. This "structural dispersion" means that regardless of their size, every sphere reflects the exact same shade of blue or green.
Built-in Color Filters: The damselflies "load" their spheres with a yellow pigment. This pigment acts like a filter, absorbing messy, unwanted light while making the main color appear much deeper and more saturated.
Tali Lemcoff | Photo credit: Shauli Landner
"Nature has found an elegant way to produce perfect colors using imperfect parts," says Lemcoff. "These strategies could show us in the future how to build high-quality optical materials using sustainable, organic ingredients instead of the synthetic chemicals we rely on today".
Lemcoff is a recipient of an Azrieli Graduate Fellowship.
The interdisciplinary team included researchers from the Weizmann Institute of Science, Lund University, Aalto University, and the University of Bristol.
This work was supported by the European Research Council (Grant No. 852948, “CRYSTALEYES” and Grant No. 101096020, "BoX-BOOM"), the Human Frontier Science Program (Grant No. RGP0037/2022), the Israel Science Foundation (Grant Nos. 1565/22 and 833/23), and the Research Council of Finland (Grant No. 347789).
Photo Caption: Highly saturated thorax colors in blue-tailed damselflies. (A) The male blue-tailed damselfly (Ischnura elegans). Photo credit: Ian Kirk. (B) Juvenile thoraxes during the development (i–iv). Right; tail region. (C) Reflectance spectra from the thoraxes and tail also exhibiting an intensifying shoulder peak at 430 nm. The black arrow indicates the color progression over ontogeny. (D) The spectra in (C) plotted on a CIE chromaticity diagram. w; white point of standard illuminant D65 corresponding to average daylight (saturation increases with distance from the white point). Dotted triangle; the sRGB color space, dashed rectangle; enlarged region of interest in (E). (E) Reflectance spectra collected from ~100 damselflies, converted to chromaticity coordinates and plotted on a CIE chromaticity diagram, exhibiting a gradual color change from green to blue. Photo Credit: Reproduced with permission from Proceedings of the National Academy of Sciences (PNAS)Changes in nanosphere size during ontogeny. (A) Cryo-SEM micrograph of a damselfly tail showing a cross-section through the epidermis. Yellow arrowheads; direction of incident light. (B) Box chart showing the sizes of nanospheres extracted from individuals with different thorax colors as well as tails. The average diameter and the SD measured in each specimen (nm) is displayed on the chart. (C) Cryo-SEM images of pteridine nanospheres in the distal epidermis in thoraxes (i–iv) and a tail (v). The colors of the box chart in (B) and panel bars in (C) are the CIE representation of the reflectance measured from the specific tail/thorax analyzed. Photo Credit: Reproduced with permission from Proceedings of the National Academy of Sciences (PNAS)
Blue-tailed female damselfly Photo Credit: Ian Kirk
Scientists at Ben-Gurion University of the Negev (BGU) have uncovered for the first time the "ingenious" biological strategies that allow blue-tailed damselflies to produce strikingly vivid, angle-independent colors. The study, published in the Proceedings of the National Academy of Sciences (PNAS)(https://www.pnas.org/doi/10.1073/pnas.2527433123), provides a new blueprint for creating sustainable, highly saturated photonic materials that could replace toxic synthetic pigments in industries ranging from cosmetics to textiles.
Structural colors in nature are often produced by photonic glasses—randomly arranged nanospheres that scatter light. While efficient, these systems typically suffer from poor color saturation because slight variations in particle size (polydispersity) wash out the resulting hue.
The damselfly’s secret: structural dispersion
Prof. Benjamin A. Palmer | Photo: Dani Machlis/BGU
The research team, led by Prof. Benjamin A. Palmer and PhD student Tali Lemcoff from BGU’s Department of Chemistry, discovered that blue-tailed damselflies (Ischnura elegans) overcome these physical limitations using two elegant evolutionary
