*Article* **Nanoimprint Replication of Biomimetic, Multilevel Undercut Nanostructures**

**Michael Muehlberger 1,\* , Stephan Ruttloff <sup>2</sup> , Dieter Nees <sup>2</sup> , Amiya Moharana 1,2, Maria R. Belegratis <sup>2</sup> , Philipp Taus <sup>3</sup> , Sonja Kopp <sup>1</sup> , Heinz D. Wanzenboeck <sup>3</sup> , Adrian Prinz <sup>4</sup> and Daniel Fechtig <sup>1</sup>**


**Abstract:** The nanoimprint replication of biomimetic nanostructures can be interesting for a wide range of applications. We demonstrate the process chain for Morpho-blue-inspired nanostructures, which are especially challenging for the nanoimprint process, since they consist of multilayer undercut structures, which typically cannot be replicated using nanoimprint lithography. To achieve this, we used a specially made, proprietary imprint material to firstly allow successful stamp fabrication from an undercut master structure, and secondly to enable UV-based nanoimprinting using the same material. Nanoimprinting was performed on polymer substrates with stamps on polymer backplanes to be compatible with roller-based imprinting processes. We started with single layer undercut structures to finally show that it is possible to successfully replicate a multilayer undercut stamp from a multilayer undercut master and use this stamp to obtain multilayer undercut nanoimprinted samples.

**Keywords:** nanoimprint lithography; UV-NIL; biomimetics; morpho butterfly
