Cornell researchers mimic riflebird feathers to make ultrablack cloth

Cornell Researchers Mimic Riflebird Feathers to Make Ultrablack Cloth (Image: Canva)

A fabric that seems to swallow light feels like something from fiction, yet researchers now report a textile that comes remarkably close. A Cornell University team has developed an ultrablack wool material that holds its darkness from several angles, offering new possibilities for design and technology.

Ultrablack fabric design

The team asked how nature traps light so effectively. Their search focused on the magnificent riflebird, whose feathers reflect less than 0.5% of incoming light. The Cornell group studied this structure while working on a white merino wool knit fabric. They treated the material with polydopamine, then etched it inside a plasma chamber to form nanofibrils. These spiky growths mimic the riflebird’s tightly bunched feather barbules, which direct light inward and keep it from escaping.

The researchers said the method was simple, scalable and suitable for natural fibres. The material could be worn easily and did not lose its darkness when seen from different angles. Their patent filing aims to support future commercial use on wool, silk and cotton.

Riflebird inspiration questions

Why does the riflebird appear so black? The answer lies in melanin pigment and complex feather structure. The bird’s plumage appears ultrablack only when viewed head-on but turns shiny at wider angles. The Cornell team wanted to avoid this issue. Polydopamine, a synthetic melanin, helped the dye reach deep into each wool fibre. Plasma etching then removed surface layers and left nanofibrils behind, creating a light-trapping network within the fabric.

The team analysed riflebird feathers closely to understand these layered features. They noted similar effects in fish and butterflies, which also rely on melanin and structural arrangements to manipulate light.

Testing and textile performance

The group reported an average total reflectance of 0.13%. This made their wool sample the darkest fabric yet described in scientific literature. Their results appeared in Nature Communications. The textile remained ultrablack across a 120-degree span, matching its appearance from straight ahead to 60 degrees either side. The researchers said current commercial materials do not maintain such consistent darkness.

The fabric’s performance raised new questions about future uses. Could ultrablack textiles improve cameras, solar panels or telescopes? Could clothing design shift with materials that retain deep colour from every angle? The team now hopes to form a company to explore these possibilities further.