Useful photonic components inspired by origami, such as space-based solar panels and telescope mirrors that unfold once reaching orbit, are not new. In contrast to light-actuated folding research from North Carolina State University (Raleigh, NC), researchers from Johns Hopkins University (Baltimore, MD) and the US Army Research Laboratory (Adelphi, MD) have taken the origami concept a step further: They developed a methodology to trigger the folding process for microstructures from afar using low-power handheld lasers.
The process essentially consists of a laser-actuated hinge that folds upon illumination by a compact, inexpensive source such as a 532 nm green laser pointer. A pre-stressed metallic bilayer of chromium-over-gold covered with a heat-activated polymer is patterned between unstressed rigid microstructure segments 300 μm to 3 mm long. The polymer-topped hinges are sequentially illuminated by the laser to begin the folding process, where a two-dimensional (2D), flat, lithographically patterned object is converted into a 3D microstructure. Laser actuation depends on laser wavelength, intensity, and focus; the microstructures can be folded from distances of up to 3 ft and, remarkably, panels can be folded in time periods as short as 67 ms. Contact David Gracias at [email protected].
