Cavitation holds the promise of a new and exciting way to fabricate both top down and bottom up nanostructures. Cavitation bubbles are created when a liquid boils under less than atmospheric pressure. The collapse process occurs supersonically and generates a host of physical and chemical phenomena. The collapse of a cavitation bubble near an object occurs asymmetrically and launches a reentrant microjet directly towards it.
Examples of cavitation's top-down capability include drilling nanoholes as small as a few nanometers. This is evidenced by the ability of cavitation reentrant microjets to puncture a hole only a few nanometers wide in a cell membrane without killing the cell and then causing a single DNA strand break in the nucleus. Cavitation nanoholes could be used to lighten or allow flow to pass through MEMS structures or to create bearings. Another top down process exhibited by cavitation reentrant microjets is the potential to nanomachine a structure, by controlling the size, strength and location of the cavitation bubble reentrant jet impact. Micro-jet impact can also be used to nanohammer sub-micron structures. Particle size reduction through cavitation is routinely used to create nanometer-sized particles.
Examples of bottom up cavitation nanoprocesses are just as diverse. The high-speed impact of particles carried by a cavitation microjet can nanoweld them together. If the impact welding process were to be controlled, it may be possible to assemble complex structures via nanowelding. Cavitation reentrant microjets could be used to implant nanoparticles into existing structures. Cavitation dynamics can naturally assemble a variety of structures such as hollow liposome spheres and may be responsible for assembling RNA or DNA itself. The bottom up capability of cavitation could form the basis of new manufacturing techniques for integrated circuits and other applications.
A nanobot armed with a cavitation toolkit may be the future basis for the first practical and versatile nanoassembler. Cavitation reentrant jets could even be used to propel the nanobot. The potential of cavitation as the next wave in nanomanufacturing is examined in the light of current technology.
Mark L. LeClair
25 Jesse Daniel Drive
Buxton, ME 04093
Ph. & FAX: 207-929-6226