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

最近的研究表明，通常采用硅微加工技术构建的工程组件的自组装可以成为制造强大的复杂微电子微系统的使能技术，该系统包含机械，光学和无线组件。自组装可以产生包含数千或数百万个部件的微系统，从而消除了对传统的顺序拾取和放置方法的依赖。提出了一种利用毛细作用和界面能作为动力的微自组装方法。具有特殊设计的疏水“结合位点”的零件和衬底在浸入水介质时将相互附着。这个高风险、高潜在回报项目的直接目标是在硅微加热阵列上使用薄膜生物材料（等离子体聚合n-异丙基丙烯酰胺，ppNIPAM，由华盛顿大学工程生物材料中心开发）的新型自组装技术的概念验证。这种方法利用了NIPAM的一个显著特性，它在大约32℃时从亲水性可逆地转换为疏水性。在这个项目中，ppNIPAM将被涂覆在微机械加热器阵列上，有效地创建一个“可编程”表面，在这种表面上，自组装只在选定的加热（即疏水）位置进行。这个项目的一个关键点是将生物材料集成到MEMS器件中。如果成功，这项技术将对目前现有的微组装方法提供根本性的改进，并可能引发更大的研究努力和许多实际应用，例如在下一代便携式通信设备或分布式微传感器网络中。除了微型自组装外，ppNIPAM微加热器阵列还有其他令人兴奋的可能应用。与Buddy Ratner教授（UWEB）合作，这项工作将探索创造用于控制蛋白质吸附的微阵列（“蛋白质芯片”）和用于控制药物释放的可变渗透性薄膜的可能性。

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.