The device is resonant at 24-27kHz according to the datasheet, so a square wave drive through a small inductor should be OK. In fact page 17 shows a square wave drive.Unfortunately, the datasheet does not appear to give any indication of the power consumption of the device, other than that the output transistors in the suggested circuit are specified as 500mA types. The NE555 is rated at 225mA, so it might be sufficient at lower drive voltages. My choice would be to generate a 26kHz square wave using one of the Arduino counter/timers, and use a MCP1407 mosfet driver chip to amplify the output and drive the device at up to 18Vp-p. Connect a small inductor and a 1uF capacitor in series between the MCP1407 output and the fan, and a resistor (e.g. 100k) in parallel with the fan.
I got this from google .. weirdhttp://forum.freetronics.com/viewtopic.php?t=5352