Abstract: There is described an authentication system in which during an enrolment process a distinctive characteristic of a subject being enrolled is measured to generate a reference number representative of the subject. Authentication data is then generated using the reference number, and the authentication data is stored for use in a subsequent verification process. During verification, the representative characteristic of the subject being verified is re-measured to generate a test number representative of the subject being verified and the authentication data during enrolment is retrieved. The authentication system then checks for equality between the test number and the reference number using the retrieved authentication data. If the test number and the reference number are equal, then the authenticity of the subject is verified, otherwise the authenticity is denied.

Abstract: Provided are methods of forming sealed via structures. One method involves: (a) providing a semiconductor substrate having a first surface and a second surface opposite the first surface; (b) forming a layer on the first surface of the substrate; (c) etching a via hole through the substrate from the second surface to the layer, the via hole having a first perimeter at the first surface; (d) forming an aperture in the layer, wherein the aperture has a second perimeter within the first perimeter; and (e) providing a conductive structure for sealing the via structure. Also provided are sealed via structures, methods of detecting leakage in a sealed device package, sealed device packages, device packages having cooling structures, and methods of bonding a first component to a second component.