Microacoustics/Nanoacoustics

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Overview | BioNEMS | Microacoustics/Nanoacoustics | Microfluidics/Nanofluidics | Molecular Mechanics | Optofluidics | Plasmonics

Micro/Nano acoustics deals with the study and application of mechanical waves in the micro-/nano- meter scale. Enabled by MEMS/NEMS technologies, it offers a noninvasive solution for many applications such as “lab-on-a-chip”. Along this line, the Penn State Bio-NEMS laboratory aims to (1) develop effective techniques to filter, guide and confine acoustic energies at micro/nano meter scales, and (2) manipulate (e.g., focus, trap, and pattern) micro/nano objects (e.g., fluorescent beads, carbon nanotubes, DNAs, and cells) in microfluidic environments using acoustic waves.

Figure 1 shows a wide-band acoustic collimation lens using phononic crystal (PC) composites. In comparison to a single PC, a PC composite structure that is composed of two sequenced PCs with different filling ratios can increase the collimation region by a factor of 240%-375%. The methodology described in this letter will prove useful in applications that require confined acoustic energy flow over long operation distances, such as acoustic imaging, drug delivery, cell sonoporation and non-destructive evaluation (NDE).

Figure 2 shows an on-chip microparticle focusing technique using standing surface acoustic waves (SSAW). In comparison to other particle focusing techniques, including hydrodynamic, electro-kinetic and dielectrophoresis (DEP) focusing, this method is simple, fast, dilution-free, and can be used to focus virtually any micro/nano particles. Moreover, the transparency of the focusing device makes it compatible with most optical characterization tools used in biology and medicine. In contrast to the bulk acoustic waves (BAW)-based microparticle manipulation method, the SSAW-based technique localizes most of the acoustic energy on the surface of the substrate and has little loss along the propagation line, thus lowering the power consumption and improving the uniformity of the standing waves. The technique is compatible with standard soft lithography techniques. We expect that it can be used in a wide variety of on-chip biological/biochemical applications.

Figure 1: (Left) FDTD simulation on wave propagation through a PC composite, featured as cover image of Applied Physics Letters. (Right) PCs arrangement and simulated energy confinement of acoustic waves with varying frequency when passing through the PC composite.

Figure 2: (Left) Schematic drawing of the SSAW-based focusing, featured as the cover image of IEEE Nanotechnology Magazine. (Right) Experimental results in monitoring the focusing effect.

1. Jinjie Shi, Sz-Chin Lin, Tony Jun Huang, Wide-Band Acoustic Collimating by Phononic Crystal Composites, Applied Physics Letters, Vol. 92, No. 11, 111901, 2008. (featured as front cover image) [PDF]
2. Jinjie Shi, Xiaole Mao, Daniel Ahmed, Ashley Colletti, Tony Jun Huang, Focusing Microparticles in a Microfluidic Channel with Standing Surface Acoustic Waves (SSAW), Lab on a Chip, Vol. 8, pp. 221-223, 2008 (will be featured as front cover image in IEEE Nano Magazine). [PDF]