Fabrication of 3D micro-cantilevers based on MBE-grown strained semiconductor layers

Microassembly based on hands free origami with bidirectional curvature

“…In this approach, specific regions of a flat sheet are cut out, bent up to form a mountain fold, bent down to form a valley fold, or left flat. Our strategy uses thin film sheets with two kinds of hinges: 16,17 ͑1͒ A bilayer hinge consisting of a chromium ͑Cr͒/copper ͑Cu͒ bilayer, which curves into the substrate ͑we denote this curvature as a positive fold angle͒; and ͑2͒ a trilayer hinge consisting of a chromium ͑Cr͒/copper ͑Cu͒/chromium ͑Cr͒ that curves away ͑negative fold angle͒ from the substrate. In both cases, folding occurs spontaneously as a result of the large ͑ϳ1 GPa͒ residual tensile stress within the Cr film, while the Cu provides structural support.…”