Professor Ken Frampton's acoustic streaming pump uses an ultrasonic transducer to produce the sound waves that transport fluorescent particles through the fluid-filled tube.

Vanderbilt acoustics specialist Kenneth D. Frampton, assistant professor of mechanical engineering, is harnessing the power of sound to move fluids and microscopic particles in chemical detection systems such as pollution and exhaust monitors.
       Studying a phenomenon called acoustic streaming, Professor Frampton and his associates are using sound waves to move viscous fluids and the microscopic particles suspended in the fluids. The project, funded by the National Science Foundation, is designed to determine how acoustic streaming might be put to work in microelectrical mechanical systems (MEMS).
       "Current MEMS pump designs require intricate check valves and diaphragm pumping actions," Professor Frampton says. "The acoustic streaming method could be relatively simple to manufacture at high volumes and would be inexpensive."
       Professor Frampton is conducting fundamental research on the acoustic streaming effects, using a second-stage prototype of an acoustic streaming pump. The pump consists of a vibrating ultrasonic transducer at one end of a small-diameter tube filled with glycerin-thickened water and fluorescent particles. Sound waves generated by the vibrating transducer move through the viscous fluid, transferring energy to move the fluorescent particles. The movement of the particles through the fluid is tracked and charted to help researchers to better understand the physics of acoustic streaming.
       The next-stage prototype will include transducers at each end of the tube, which will produce ultrasonic waves that will interact with each other in ways that will cause the particles to collect at wave intersections. By adjusting the frequencies of the transducers, the wave intersections can be moved, moving the particles along with them.
       "This method ultimately could be used in bi-directional pumping, particle separation and 'valveless valving' that prevents backward flow down a channel," Professor Frampton says. "The technique could also be put to use in microchip blood analysis tools for medical tests, a lab on a chip'."