Gallery: Tiny semiconductor crystals that mimic plant seed pods

Kat Gilmore on September 14, 2026

Optical microscope image of a single crystal ribbon about one millimeter long—roughly the thickness of a credit card—that twists 86 times along its length. It is about one thousandth of one millimeter wide, which is why it looks like a pencil line. The image is stitched together from dozens of overlapping microscope frames. (Image provided by Wenhao Shao, University of Georgia, 2026.)

Gallery: Tiny semiconductor crystals that mimic plant seed pods

Image 1: Microribbon with 86 twists (1 millimeter long)Optical microscope image of a single crystal ribbon about one millimeter long—roughly the thickness of a credit card—that twists 86 times along its length. It is about one thousandth of one millimeter wide, which is why it looks like a pencil line. The image is stitched together from dozens of overlapping microscope frames. (Image provided by Wenhao Shao, University of Georgia, 2026.)

Optical microscope image of a crystal ribbon making 14 full turns as it grows outward from a dense cluster of crystals. The regular pinching along its length is the twist itself: the ribbon appears narrow each time it turns edge-on to the viewer. (Image provided by Wenhao Shao, University of Georgia, 2026.)

Image 2: Microribbon with 14 twistsOptical microscope image of a crystal ribbon making 14 full turns as it grows outward from a dense cluster of crystals. The regular pinching along its length is the twist itself: the ribbon appears narrow each time it turns edge-on to the viewer. (Image provided by Wenhao Shao, University of Georgia, 2026.)

Optical microscope image of a crystal that has coiled into a helix, like a spring or a corkscrew, rather than simply twisting. The flat plate-shaped crystal at top right is the same material grown in its ordinary, untwisted form. (Image provided by Wenhao Shao, University of Georgia, 2026.)

Image 3: Coiled crystal, No. 1Optical microscope image of a crystal that has coiled into a helix, like a spring or a corkscrew, rather than simply twisting. The flat plate-shaped crystal at top right is the same material grown in its ordinary, untwisted form. (Image provided by Wenhao Shao, University of Georgia, 2026.)

Optical microscope image of a second coiled crystal. The scalloped outline is the coil seen side-on, spiraling toward the viewer and away again. Same crystal as Image 5. (Image provided by Wenhao Shao, University of Georgia, 2026.)

Image 4: Coiled crystal, No. 2Optical microscope image of a second coiled crystal. The scalloped outline is the coil seen side-on, spiraling toward the viewer and away again. Same crystal as Image 5. (Image provided by Wenhao Shao, University of Georgia, 2026.)

The same coiled crystal as Image 4, glowing violet under ultraviolet light. The glow comes from the crystal itself, not from any added dye—the same effect as a highlighter pen under a blacklight. (Image provided by Wenhao Shao, University of Georgia, 2026.)

Image 5: Coiled crystal, No. 2, photoluminescenceThe same coiled crystal as Image 4, glowing violet under ultraviolet light. The glow comes from the crystal itself, not from any added dye—the same effect as a highlighter pen under a blacklight. (Image provided by Wenhao Shao, University of Georgia, 2026.)

Optical microscope image of many crystal ribbons branching outward from a common stem, resembling a fern. Every branch is a separate twisted crystal. The team calls these structures ribbon forests. (Image provided by Wenhao Shao, University of Georgia, 2026.)

Image 6: Ribbon forestOptical microscope image of many crystal ribbons branching outward from a common stem, resembling a fern. Every branch is a separate twisted crystal. The team calls these structures ribbon forests. (Image provided by Wenhao Shao, University of Georgia, 2026.)

The same kind of branching structure viewed between two crossed polarizing filters—the same technology as polarized sunglasses. The filters block ordinary light, so the background goes black while the crystals glow. This technique is how the team measures the twisting. (Image provided by Wenhao Shao, University of Georgia, 2026.)

Image 7: Ribbon forest, polarizedThe same kind of branching structure viewed between two crossed polarizing filters—the same technology as polarized sunglasses. The filters block ordinary light, so the background goes black while the crystals glow. This technique is how the team measures the twisting. (Image provided by Wenhao Shao, University of Georgia, 2026.)

This is a 3D computer model, not a photograph. Each pale block is one repeating unit of the crystal, roughly one-millionth of a millimeter across. No single block is twisted—the twist comes entirely from stacking each block at a slight angle to its neighbor. (Image provided by Wenhao Shao, University of Georgia, 2026.)

Image 8: 3D computer model illustrating twist, No. 1This is a 3D computer model, not a photograph. Each pale block is one repeating unit of the crystal, roughly one-millionth of a millimeter across. No single block is twisted—the twist comes entirely from stacking each block at a slight angle to its neighbor. (Image provided by Wenhao Shao, University of Georgia, 2026.)

This is a 3D computer model, not a photograph. This shows the coiled form of the ribbon wrapping around an invisible cylinder, like a ribbon curled with scissors. (Image provided by Wenhao Shao, University of Georgia, 2026.)

Image 9: 3D computer model illustrating coiled formationThis is a 3D computer model, not a photograph. This shows the coiled form of the ribbon wrapping around an invisible cylinder, like a ribbon curled with scissors. (Image provided by Wenhao Shao, University of Georgia, 2026.)

This is a 3D computer model, not a photograph. The same coiled ribbon as Image 9, seen from a different angle so the loop reads as a three-dimensional spring. (Image provided by Wenhao Shao, University of Georgia, 2026.)

Image 10: 3D computer model illustrating coiled formation, No. 2This is a 3D computer model, not a photograph. The same coiled ribbon as Image 9, seen from a different angle so the loop reads as a three-dimensional spring. (Image provided by Wenhao Shao, University of Georgia, 2026.)

Some plants fling their seeds by twisting. As a seed pod dries, its inner and outer layers shrink by different amounts and pull against each other. The pod cannot stay flat, so it curls into a spiral and springs open. We found crystals that do the same thing, for the same reason. These crystals are built from stacked sheets. On the top and bottom face of each sheet, the organic molecules line up along different directions, so the two faces pull against one another exactly as the layers of a seed pod do. The crystal cannot lie flat. It twists as it grows—some into ribbons wrung like a towel, some coiled like a spring. The surprising part is that nothing in the recipe is twisted. The molecules have no left- or right-handed form of their own. The twist comes only from how the layers are stacked, which means we can design it in, predict its shape, and switch it off. The material is a layered halide perovskite, a relative of the materials being developed for solar cells, LEDs, photonics, and quantum information science. Twisted structures respond differently to clockwise and counterclockwise light, which makes them useful for optical sensors, displays, and quantum photonics. All images provided by Wenhao Shao, University of Georgia, 2026.