The original goal was to learn how to manufacture everything from pharmaceuticals to alloys without using containers. At times compounds are too corrosive for containers to hold, or they react with containers in other undesirable ways.

    "An interesting question is, 'What will happen if a living animal is put into the acoustic field?' Will it also be stably levitated?" researcher Wenjun Xie, a materials physicist at the university told LiveScience.
 

A live beetle levitated by sound pressure in an experiment at Northwestern Polytechnical University.(Xinhua Photo) Photo Gallery >>>

   Xie and his colleagues utilized an ultrasound emitter and reflector to generate a sound pressure field between them. The emitter produced roughly 20-millimeter-wavelength sounds, meaning it could in theory levitate objects half that wavelength or less.

    After the investigators got the ultrasound field working, they used tweezers to carefully place animals between the emitter and reflector. The scientists found they could float ants, beetles, spiders, ladybugs, bees, tadpoles and fish up to a little more than a third of an inch long in midair.

    When they levitated the fish and tadpole, the researchers used a syringe to squirt water into the ultrasound field every minute.

    The levitated ant tried crawling in the air and struggled to escape by rapidly flexing its legs, although it generally failed because its feet find little purchase in the air. The ladybug tried flying away but also failed when the field was too strong to break away from.

    "We must control the levitation force carefully, because they try to fly away," Xie said. "An interesting moment was when my colleagues and I had to catch escaping ladybugs."

    The ant and ladybug appeared to suffer no ill effects following 30 minutes of levitation. The fish, according to the report, did not fare as well because of an inadequate water supply.

    "Our results may provide some methods or ideas for biology research," Xie said. "We have tried to hatch eggs of fish [during] acoustic levitation."

    The research team reported their findings online Nov. 20 in the journal Applied Physics Letters.

    (Agencies)