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/ s2 was obtained, presenting possibilities for microcentrifugation, flow sequencing, assays, and cell culturing in truly microscale lab-on-a-chip devices. © 2011 American Institute of Physics.

Treatment of surfaces to change the interaction of fluids with them is a critical step in constructing useful microfluidics devices, especially those used in biological applications. Silanization, the generic term applied to the formation of organosilane monolayers on substrates, is both widely reported in the literature and troublesome in actual application for the uninitiated. These monolayers can be subsequently modified to produce a surface of a specific functionality. Here various organosilane deposition protocols and some application notes are provided as a basis for the novice reader to construct their own silanization procedures, and as a practical resource to a broader range of techniques even for the experienced user.