Abstract: The present invention provides a method of forming a branched structure which comprises applying colloidal-sized particles over structures. The coated structures are then etched such that the structures are etched through the colloidal particles to form branched structures. The etch may be a reactive ion etch. The structures may be microstructures formed as high aspect ratio microstructures. The colloidal-sized particles may be applied as a colloidal solution and a polyelectrolyte (PE) layer may be applied to the microstructures prior to the colloidal solution to promote adsorption of the colloidal particles.