FYFD

Tag: self-healing

  • Soap Film Filter

    Soap Film Filter

    Inspired by the self-healing properties of soap films, scientists have created a liquid filter capable of trapping small particles while allowing larger ones to pass through. Instead of filtering particles by size, as conventional filters do, this liquid membrane filters particles by kinetic energy; only large, fast-moving objects  pass through while slower and smaller ones get trapped. The membrane is a mixture of deionized water and sodium dodecyl sulfate, which allows researchers to finely tune the membrane’s surface tension and, therefore, how the filter behaves. Unlike soap films, the membrane is quite long-lived and robust. The team poked one for more than 3 hours without rupturing it.

    The researchers envision some pretty neat applications for these membranes, including a surgical membrane that would keep out dust and bacteria while doctors work or a membrane in a waterless toilet that could trap odors inside. (Image and research credit: B. Stogin et al.; video credit: Science; submitted by Kam-Yung Soh)

  • Featured Video Play Icon

    Bubble Art

    Everyone loves soap bubbles, and bubble artist Melody Yang reveals how to make some pretty awesome ones in this video for Wired. The surface tension of bubbles makes them naturally seek a shape that minimizes their surface area relative to the volume they contain. For a single bubble, that’s a sphere. But once you start joining multiple bubbles, as Yang demonstrates, that minimal surface area can change, even to something unexpected like a cube.

    Bubbles also have an impressive ability to self-heal. As long as whatever passes through them is wet – whether it’s a hand, a straw, or even a ball bearing – the soap film will probably heal itself rather than break. This is a key feature for many of Yang’s tricks, including the impressive planetary bubble. (Video credit: Wired; image credits: Wired/Colossal; via Colossal)

  • Self-Healing Bubbles

    Self-Healing Bubbles

    Soap films have the remarkable property of self-healing. A water drop, like the one shown above, can pass through a bubble (repeatedly!) without popping it. This happens thanks to surfactants and the Marangoni effect. Surfactants are molecules that lower the surface tension of a liquid and congregate along the outermost layer of a soap film. When water breaks through the soap film, its lack of surfactants causes a higher surface tension locally. This triggers the Marangoni effect, in which flow moves from areas of low surface tension toward ones of high surface tension. That carries surfactants to the region where the drop broke through and helps stabilize and heal the soap film. Incidentally, the same process lets you stick your finger into a bubble without popping it as long as your hand is wet! (Image credit: G. Mitchell and P. Taylor, source)

  • Slipping Through a Soap Film

    Slipping Through a Soap Film

    A droplet falling at high speed can pass through a soap film without breaking it. On impact, the drop stretches the soap film and ultimately only passes through by getting coated with a thin shell of soap film fluid. That liquid shell is separated from the original droplet by an extremely thin air layer. This air layer isn’t typically visible, but we know that it’s there from what happens when that soap-film-shelled droplet later impacts a liquid pool. As seen above, the droplet sits on the surface until the soap film shell coalesces with the pool. This sucks the drop under, but the drop itself does not coalesce. Instead it becomes an antibubble – a submerged liquid drop surrounded by a shell of air. (Image credit: J. Zou et al., source)

  • Healing Soap Films

    Healing Soap Films

    As fragile as a soap bubble seems, these films have remarkable powers of self-healing. The animation above shows a falling water droplet passing through a soap film without bursting it. An important factor here is that the water droplet is wet–passing a dry object through a soap film is a quick way to burst it, as those who have played with bubbles know. The droplet’s inertia deforms the soap film, creating a cavity. If the drop’s momentum were smaller, the film could actually bounce the droplet back like a trampoline, but here the droplet wins out. The film breaks enough to let the drop through, but its cavity quickly pinches off and the film heals thanks to the stabilizing effect of its soapy surfactants. (Image credit: H. Kim, source)