The use of the silicone known as Poly-dimethylsiloxane (PDMS) in microfluidic and other activities has increased enormously. By means of a laser short pulse, optical breakdown of the liquid contained in a microchannel (squared cross-section with 100 μm sides) can occur; as a consequence plasma is generated and a gaseous bubble suddenly expands. The expansion of such a bubble can be so violent that the channel walls deform considerably and in some cases the detachment of the top wall from the PDMS channel is verified. Measurements of channel width reveal a relative increase up to 45 % for the tested conditions. Due to the elasticity of PDMS and surface energy values, surprisingly the top wall and channel reattach. Contrary to widely known cavitation where damage to the wall is manifested in form of pitting, we observe no permanent damage for the experimental conditions studied. We envisage the use of PDMS material in other types of applications with high relative volumetric change, such as microexplosions, ultrasonic cavitation and the like, in which there is a cyclic stress load of the PDMS material. We present a compact method to predict the reliability of PDMS for its use in cavitational events occurring inside of microfluidic channels (by force balance and energy conservation analysis).
|Title of host publication||Proceedings of the Sixth International ASME Conference on Nanochannels, Microchannels and Minichannels|
|Number of pages||4|
|Publication status||Published - Jun 2008|