Patent ID: 7955486

Claim:
A method for forming an elongated structure of a selected material, the structure extending at least partially upwards from the surface of a substrate, the method comprising the steps of: a. providing an electrically conducting substrate; b. providing an electrolyte reservoir having a dispensing end and an aperture located at the dispensing end, the size of the aperture being less than 5 micrometers, the reservoir containing i. an electrolyte solution comprising at least one ionic component; the ionic component capable of being electrodeposited to form the selected material; and ii. a reservoir electrode in electrical contact with the electrolyte solution; c. applying a potential difference between the reservoir electrode and the substrate such that the substrate has the opposite charge to the ionic component and the reservoir electrode has the same charge as the ionic component, the variation in the potential difference being less than 2%; d. bringing the aperture of the electrolyte reservoir sufficiently close to the substrate to establish a meniscus between the dispensing end of the reservoir and the substrate, thereby establishing a volume of electrolyte solution external to the reservoir between the dispensing end of the reservoir and the substrate and to establish an ionic current between the reservoir electrode and the substrate, thereby electrodepositing the selected material on the substrate; and e. increasing the vertical separation between the reservoir and the substrate while maintaining an ionic current therebetween, thereby electrodepositinq a wire of the selected material which extends at least partially upwards from the surface of the substrate, wherein the current is constant to within 15% after an initial stabilization period, the separation rate of the reservoir and the substrate is selected to be in the range between 50 nm/s and 500 nm/s and the motion of the reservoir and the electrodeposition rate are synchronized to maintain the meniscus between the dispensing end of the reservoir and the electrodeposited wire, thereby maintaining a volume of electrolyte solution external to the reservoir between the dispensing end of the reservoir and the electrodeposited material.