Picogram material dosing of microstructures

A solution delivery platform comprised of a suspended microcapillary connected to a microwell enables picogram solute deposition on suspended structures. Precision material placement in the capillary from a 100 pl drop inkjetted into the well is achieved without the destruction of the microstructure and adjacent submicron electrostatic gaps. This method scales to smaller structures without the need for drop miniaturization. The theory behind the solute transfer in the system is developed. Three regions in the drying process are observed and match with the model. The "accumulation" region builds solute concentration in the capillary. The "solidification" region initiates the solidification of solute starting at the free end of the capillary. The "termination" region is characterized by a rapid increase in the solidification due to an increase in the well concentration near the end of the drop lifetime. The accumulation time and solidification rate dependence on concentration compare well with the model. (C) 2009 American Institute of Physics. [doi: 10.1063/1.3248305]