Abstract: The current invention introduces a method of crystal film's growth of Gallium Nitride and related alloys over a novel class of the substrates using Vapor Phase Epitaxy technique. This said novel class of the substrates comprises single crystal lattice matched, partially matched or mismatched metallic substrates. The use of such substrates provides exceptional thermal conductivity and application flexibility, since they can be easily removed or patterned by chemical etching for the purposes of additional contact formation, electromagnetic radiation extraction, packaging or other purposes suggested or discovered by the skilled artisan. In particular, if patterned, the remaining portions of the said substrates can be utilized as contacts to the semiconductor layers grown on them. In addition, the said metallic substrates are significantly more cost effective than most of the conventional substrates.

Abstract: A novel method suitable for commercially mass production of hollow microneedle with high quality for delivery of drugs across or into biological tissue is provided. It typically includes the following processes: (1) coating an elongated template of a first material with a second material to form a cover; (2) removing tips of the template and cover to form an opening in the cover; and (3) removing the template of the first material to obtain hollow microneedles of the second material. This simple, efficient and cost-effective fabrication method can mass produce hollow microneedle arrays involving no complicated and expensive equipments or techniques, which can be used in commercial fabrication of hollow needles for delivering drugs or genes across or into skin or other tissue barriers with advantages of minimal damage, painless, long-term and continuous usages.