Silicon surface mimics butterfly wing structure to repel water

An international team of researchers has replicated the water-repelling properties of the mountain swallowtail butterfly’s wings.

In nature, the butterfly is able to shed water because of the way structures in its wings trap air and create a cushion between water and wing.

According to a statement from the American Institute of Physics, past attempts at artificial air traps tended to lose their contents over time due to external perturbations.

Now, an international team of researchers from Sweden, the US and Korea is said to have taken advantage of what might normally be considered defects in the nanomanufacturing process to create a multi-layered silicon structure that traps air and holds it for longer than one year.

The researchers used an etching process to carve out micro-scale pores and sculpt tiny cones from the silicon.

The team found that features of the resulting structure that might usually be considered defects, such as undercuts beneath the etching mask and scalloped surfaces, improved the water-repellent properties of the silicon by creating a multi-layered hierarchy of air traps.

The intricate structure of pores, cones, bumps and grooves also succeeded in trapping light, almost perfectly absorbing wavelengths just above the visible range.

The biologically inspired surface, described in the AIP’s journal Applied Physics Letters, could find uses in electro-optical devices, infrared imaging detectors or chemical sensors.