Patent ID: 7972661

Claim:
A method of providing a plurality of particles for contact with one or more target objects, the method comprising: providing one or more target objects; providing an electrospray apparatus, wherein the electrospray apparatus comprises an inner opening and an outer opening concentric with the inner opening terminating at a dispensing tip of the electrospray apparatus; providing a first flow of a liquid to the inner opening, wherein the first flow of the liquid comprises biological material; providing a second flow of a liquid to the outer opening; generating a spray of particles forward of the dispensing tip, wherein generating the spray of particles comprises dispensing a plurality of microdroplets having an electrical charge associated therewith from the dispensing tip by creating a cone jet from the first and second flow at the dispensing tip using a nonuniform electrical field between the dispensing tip and the one or more target objects, wherein the second flow of the liquid is used to adjust the conductivity of the first flow of the liquid comprising the biological material, and further wherein the plurality of particles having a nominal diameter of less than 1 micrometer are formed as the microdroplets evaporate; and contacting the one or more target objects with one or more of the plurality of particles using the nonuniform electrical field created between the dispensing tip and the one or more target objects.