Rotational microfluidic motor for on-chip microcentrifugation

We report on the design of a surface acoustic wave (SAW) driven fluid-coupled micromotor which runs at high rotational velocities. A pair of opposing SAWs generated on a lithium niobate substrate are each obliquely passed into either side of a fluid drop to drive rotation of the fluid, and the thin circular disk set on the drop. Using water for the drop, a 5 mm diameter disk was driven with rotation speeds and start-up torques up to 2250 rpm and 60 nN m, respectively. Most importantly for lab-on-a-chip applications, radial accelerations of 172 m/s(2) was obtained, presenting possibilities for microcentrifugation, flow sequencing, assays, and cell culturing in truly microscale lab-on-a-chip devices. (C) 2011 American Institute of Physics. [doi: 10.1063/1.3600775]