Lay Chee Leng, Koh Charlynn Sher Lin, Lee Yih Hong, Phan-Quang Gia Chuong, Sim Howard Yi Fan, Leong Shi Xuan, Han Xuemei, Phang In Yee, Ling Xing Yi
Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore 637371, Singapore.
Institute of Materials Research and Engineering, Agency for Science, Technology and Research (A*STAR), 2 Fusionopolis Way, Innovis, #08-03, Singapore 138634, Singapore.
ACS Appl Mater Interfaces. 2020 Mar 4;12(9):10061-10079. doi: 10.1021/acsami.9b20911. Epub 2020 Feb 20.
Two-photon lithography (TPL) is an emerging approach to fabricate complex multifunctional micro/nanostructures. This is because TPL can easily develop various 2D and 3D structures on a variety of surfaces, and there has been a rapidly expanding pool of processable photoresists to create different materials. However, challenges in developing two-photon processable photoresists currently impede progress in TPL. In this review, we critically discuss the importance of photoresist formulation in TPL. We begin by evaluating the commercial photoresists to design micro/nanostructures for promising applications in anti-counterfeiting, superomniphobicity, and micromachines with movable parts. Next, we discuss emerging hydrogel/organogel photoresists, focusing on customizing photoresist formulations to fabricate reconfigurable structures that can respond to changes in local pH, solvent, and temperature. We also review the development of metal salt-based photoresists for direct metal writing, whereby various formulations have been developed to enable applications in online sensing, catalysis, and electronics. Finally, we provide a critical outlook and highlight various outstanding challenges in formulating processable photoresists for TPL.
双光子光刻（TPL）是一种用于制造复杂多功能微纳结构的新兴方法。这是因为双光子光刻能够轻松地在各种表面上构建各种二维和三维结构，并且可用于制造不同材料的可加工光刻胶库正在迅速扩大。然而，目前开发双光子可加工光刻胶面临的挑战阻碍了双光子光刻技术的发展。在这篇综述中，我们批判性地讨论了光刻胶配方在双光子光刻中的重要性。我们首先评估用于设计微纳结构的商业光刻胶，这些微纳结构在防伪、超疏 omniphobicity 和具有可移动部件的微机器等有前景的应用中具有重要价值。接下来，我们讨论新兴的水凝胶/有机凝胶光刻胶，重点是定制光刻胶配方以制造能够响应局部pH值、溶剂和温度变化的可重构结构。我们还回顾了用于直接金属写入的金属盐基光刻胶的发展，通过开发各种配方实现了其在在线传感、催化和电子学等领域的应用。最后，我们给出了批判性的展望，并强调了在为双光子光刻制定可加工光刻胶时面临的各种突出挑战。
