SGER: Selfassembly of Heterogeneous Microsystems on ppNIPAM-Coated Microheater Arrays

University Of Washington, Seattle WA

Investigators

Abstract

Recent research has demonstrated that self-assembly of engineered components, usually built with silicon micromachining techniques, can be an enabling technology in the fabrication of powerful complex microelectronic microsystems that incorporate mechanical, optical, and wireless components. Self-assembly can produce microsystems containing thousands or millions of parts, eliminating the reliance on conventional, sequential pick-and-place approaches. A promising approach towards micro self-assembly is proposed, which employs capillary action and interfacial energies as its driving force. Parts and substrates with specially designed hydrophobic 'binding sites' will attach to each other when immersed in an aqueous medium. The immediate goal of this high-risk, high-potential-payoff project is a proof-of-concept demonstration of a novel selfassembly technique using a thin-film biomaterial (plasma polymerized N-isopropylacrylamide, ppNIPAM, developed at the University of Washington Engineered Biomaterials Center,) on silicon microheater arrays. This approach exploits a remarkable property of NIPAM, which reversibly switches from hydrophilic to hydrophobic at approximately 32C. In this project, ppNIPAM will be coated onto micromachined heater arrays, effectively creating a 'programmable' surface where self-assembly takes place only on selected, heated (i.e., hydrophobic) sites. A key point in this project will be the integration of a biomaterial into a MEMS device. If successful, this technique will provide a radical improvement over currently existing microassembly approaches, and could likely set off a larger research effort and numerous practical applications, e.g. in the next generation of portable communication devices or distributed microsensor networks. In addition to micro self-assembly, arrays of ppNIPAM microheaters have other exciting possible applications. In collaboration with Prof. Buddy Ratner (UWEB), this work will explore possibilities to create micro arrays for controlled protein adsorption ("protein chips"), and films with variable permeability for controlled drug release.