Title :
Ultrasonically induced microtransport
Author :
Moroney, R.M. ; White, R.M. ; Howe, R.T.
Author_Institution :
Dept. of Electr. Eng. & Comput. Sci., California Univ., Berkeley, CA, USA
fDate :
30 Jan-2 Feb 1991
Abstract :
Fluid motion induced by traveling flexural waves in 4 μm thick membranes was observed using 2.5 μm diameter polystyrene spheres in water to make the fluid motion visible. Visual observation of the spheres indicates that they move in the direction of wave propagation with a speed proportional to the square of the acoustic amplitude. The maximum speed is 130 μm/s for an RF drive voltage of 7.1 Vrms at 3.5 MHz; the wavelength is 100 μm. Standing Lamb waves, which can be seen visually with a phase-contrast microscope, are found to trap particles, including bacteria located in a drop of water that contacts the membrane. A first order model of Lamb-wave micropumping is presented, based on acoustic streaming theory. Important parameters for device design and operation are discussed, along with options for integrating the device into microflow systems. Possible applications include temperature redistribution in ICs and miniature chemical processing systems
Keywords :
acoustic streaming; flow visualisation; surface acoustic waves; ultrasonic effects; wave propagation; Lamb-wave micropumping; RF drive voltage; acoustic streaming theory; chemical processing systems; first order model; microflow systems; phase-contrast microscope; polystyrene spheres; temperature redistribution; traveling flexural waves; wave propagation; Acoustic devices; Acoustic propagation; Acoustic waves; Biomembranes; Chemical processes; Microorganisms; Microscopy; Radio frequency; Temperature; Voltage;
Conference_Titel :
Micro Electro Mechanical Systems, 1991, MEMS '91, Proceedings. An Investigation of Micro Structures, Sensors, Actuators, Machines and Robots. IEEE
Conference_Location :
Nara
Print_ISBN :
0-87942-641-1
DOI :
10.1109/MEMSYS.1991.114810
