Design of micro-scale highly expandable networks of polymer-based substrates for macro-scale applications FEATURED ARTICLE

• Published in: Smart materials and structures Vol. 19; no. 4; p. 045013
• Main Authors: Lanzara, G, Feng, J, Chang, F-K
• Format: Journal Article
• Language: English
• Published: 01.04.2010
• Subjects: Electronics; Failure; Nanocomposites; Nanomaterials; Nanostructure; Networks; Reduction; Stretching; Wire
• ISSN: 0964-1726
• DOI: 10.1088/0964-1726/19/4/045013

An investigation was performed to design a network of nodes interconnected by conductive microwires in polymer-based substrates, which can be expanded to cover an area which is several orders of magnitude larger for macro-scale integration. The substrates can be potentially designed to host nano/micro-sensors/actuators and electronics to create a functional network for various applications. The major focus of the research is to develop a process to ensure that the network transition from a micro-scale fabrication to a macro-scale deployment is controllable, reliable and stable without failure. The key concept of the proposed design is to remove microscopically unnecessary materials from the substrate to create a network of infrastructures that can be stretched and expanded to a macro-scale size of several orders of magnitude. Material reduction is achieved by engineering a network of thousands of micronodes interconnected by extendable microwires, which are the key element to perform uniform expansions of the network in all directions, to allow precise location of the nodes, to maximize the polymer expansion per unit area and to allow translation only of the nodes. The number of nodes, the bidimensional stretching ratio of the network and the material reduction are linked to the processable substrate size, to the final area coverage upon full expansion and to the in-plane area of the nodes and wires. In this paper we demonstrate that an expandable network with 200 mu m diameter nodes and 4 mu m wide wires is characterized by a 99.7% material reduction and a 25 600% bidimensional stretching ratio. A 5041 micronode network was built on a 100 mm diameter wafer and was expanded to a final area of 1 m2 at low strain levels. The expanded node network is integrated into materials of different rigidities and is proven to resist under bending and twisting of the hosting material. The proposed flexible, expandable polymer design is a cost-effective approach that has the potential to build a bridge between the engineering of the nano/microscopic devices and their exploitation on the macroscopic scale. In particular, this approach can be used for wired or wireless sensor network applications as well as for the realization of innovative materials.