Conventional rigid electronic systems use a number of metallization layers to route all necessary connections to and from isolated surface mount devices using well-established printed circuit board technology. In contrast, present solutions to prepare stretchable electronic systems are typically confined to a single stretchable metallization layer. Crossovers and vertical interconnect accesses remain challenging; consequently, no reliable stretchable printed circuit board (SPCB) method has established. This article reports an industry compatible SPCB manufacturing method that enables multilayer crossovers and vertical interconnect accesses to interconnect isolated devices within an elastomeric matrix. As a demonstration, a stretchable (260%) active matrix with integrated electronic and optoelectronic surface mount devices is shown that can deform reversibly into various 3D shapes including hemispherical, conical or pyramid.

Articles you may be interested inDirect growth of hexagonal InN films on 6H-SiC by radio-frequency metal-organic molecular-beam epitaxya)

and form factor. To the best of our knowledge, a metamorphic microphone array has not been reported. Within the field of metamorphic electronics, two fabrication strategies are commonly used. The first uses electronic devices in combination with a bendable carrier and bendable interconnects. Here origami- [2] and kirigami [3] like methods are used to fold the structure into a desired shape. The topological complexity dictates the number of folds that are required and certain topologies, for example, a sphere, and are difficult to fabricate. The microphone arrays discussed in this communication morph from a (i) concave to a (ii) planar to a (iii) convex and a (iv) cone-like topology, which would be very difficult to achieve using the origami/kirigami approach.An alternative to the origami-inspired method is to build on recent advancements in the field of stretchable electronics. Stretchable electronics incorporates electronic functions (in our case, microphones and other active and passive devices) inside or on top of a stretchable elastomeric membrane. One essential element is the requirement of stretchable electrical interconnects between the device elements. Different interconnect solutions are known today. Most of the solutions go back to the original work by Lacour, [4] Chen, [5] and Whitesides [6] and their respective co-workers who reported (i) metallization layers with topological wrinkles, [4] (ii) meander or horse-shoe designs, [5] and (iii) liquid metals, [6] as the stretchable interconnecting metal layers, respectively. A large set of applications have been demonstrated, which include smart clothing, [7] conformable photo voltaics, [8] optoelectronics, [9] digital cameras, [10] artificial electronic skins, [11] stretchable batteries, [12] robotics, [13] and mechanically soft and conformable health-monitoring devices [14] to give a few recent examples. However, considering the current state of the art, the number of interconnects to the isolated device elements has been small (2-4 connections per device), and the total number of devices continues to be limited (5-22 devices). [15] This points to scaling and robustness challenges.As a result, the desired microphone array has been difficult to fabricate using the reported methods. The array has a total number of 60 interconnects, contains 5 different device types, and a total of 25 commercially available surface mount devices (SMDs). This goes beyond the metrics previously reported in the field of stretchable electronics.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 (12×) 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 otherw...

Silicon carbide can be reproducibly grown on (111)Si below 600 °C by carbonization using an elemental solid carbon source in molecular beam epitaxy. The initial stages were observed by in situ reflection high-energy electron diffraction. Prior to silicon carbide growth, the continuous carbon flux lead to a transition from the (7×7) reconstruction of clean (111)Si to a carbon-induced (∛×∛)R30° structure. Above 660 °C, the silicon carbide growth starts directly on the silicon surface via three-dimensional nucleation. Below 660 °C, first a thin silicon–carbon alloy was formed by diffusion of carbon into the surface near the region with a concentration exceeding the bulk solubility in silicon.

In this work, we report on the stabilization of 3C-AlN polytype by molecular-beam epitaxy ͑MBE͒ on 3C-SiC/ Si͑111͒ pseudosubstrates. The main purpose of the present studies is to analyze the mechanisms forcing the epitaxy of the 3C-AlN at typical MBE conditions. The forces driving the cubic polytype formation have been considered including supersaturation, macroscopic stress, interfacial energy, and interface morphology. We conclude that the growth of 3C-AlN phase can be stabilized on the "rough" 3C-SiC͑111͒ surface by the polytype replication due to the lateral character of the nucleation and the reduction in the total energy of the film provided by periodical undulations of the template surface.

No abstract

Stretchable metallic interconnects are commonly designed using a meander-shaped metal track with a uniform width. This article reports on a 'stress-adaptive' metal track design which varies in width to accommodate the produced torque in the metal track during stretching. The stress-adaptive design is inspired by computational and experimental studies of two conventional meander-shape metal tracks identifying a common failure mode; specifically, the propagation of torque leading to twist and mechanical fatigue. The understanding gained led to the stress-adaptive design. The stress-adaptive structure is compared with horseshoe-and U-shaped references and shows improvements in the stress distribution, levels of twist, maximum level of elongation (>320%), and required stretch and release cycles (>6000 at 150% elongation) to cause failure in a long term cycling test.

No abstract