A droplet volume adjustable single-heater microinjector based on digital current path control

In this work, we present a novel multilevel droplet volume adjustable single heater microinjector. The present microinjector adjusts droplet volume by controlling current paths in a single microheater, while the previous works use multiple heaters or voltage control method. In the experiment, the input power is changed from 8.7/spl mu/W to 24.9/spl mu/W for R type and from 8.1/spl mu/W to 43.8/spl mu/W for C type as the current path changing. The projected bubble area is also changed from 440/spl mu/m/sup 2/ to 1360/spl mu/m/sup 2/ and from 800/spl mu/m/sup 2/ to 3300/spl mu/m/sup 2/, respectively. It is found that the ejected droplet volume is varied from 9.4pl to 20.7pl at 3 levels for R type and from 7.4pl to 27.4pl at 5 levels for C type, while the droplet velocity is increased from 0.8m/s to 1.7m/s for R type and from 0.5m/s to 2.8m/s for C type microinjector.