Utilization of n-dodecane as coupling layer for reusable acoustofluidic microchips

In this study, n-dodecane used as the coupling layer for reusable acoustofluidic microchips was investigated. n-dodecane has the similar viscosity to that of water. However, it possesses much lower surface tension and higher boiling point compared to water. When dispensing a droplet of n-dodecane on lithium niobate (LiNO3) substrate with interdigital transducers and placing the polydimethylsiloxane microchannel on top of it, n-dodecane can easily wick through and completely occupy the interstitial space. Moreover, it can be readily removed from the substrate without leaving residue. The experimental results showed that the reusable acoustofluidic microchips can be operated at higher input voltages and longer duration when applying n-dodecane as the coupling layer. Attenuation of the acoustic radiant force was observed through decrease of the particle velocity, which is in agreement with the literature results. Decreasing the thickness of the coupling layer can alleviate the attenuation effect and a linear relationship between particle velocity and thickness on a semi-log plot was obtained.