3D Metamorphic Stretchable Microphone Arrays

This article describes the realization of a metamorphic microphone array. The array morphs from a concave to a planar and then to a convex shape. The morphing array enables a better (12x) sound source localization when compared to existing static and planar arrangements. To enable the realization, a novel stretchable (elongated up to 320% of the original length) printed circuit board fabrication process is reported. The fabrication process enables high-temperature processing, alignment, and registration. Moreover, conventional and otherwise rigid surface mount devices (SMDs) can be used. The process allows the researcher to increase the number of devices (30 SMDs) and interconnects (60 in total) to the required level. As electrical connections, a polyimide-cladded metal track design is reported; the design sustained 11 050 stretch and release cycles. Moreover, 3D reinforcement frames are reported as an effective measure to shield the SMD components from high levels of stress. The resulting products are millimeter-thin stretchable rubber-embedded and electrically interconnected electronic structures with mechanical rubber-membrane-like properties. Morphology changes involve deflation and inflation of the membrane to bulge inward or outward. Finally, the use of 3D-shaped chaperon is discussed to provide additional shape control.