Fabrication and Characterization of Polycarbonate Substrates for High Yield Assembly of Multicomponent Biohybrid Microrobots

This paper presents polycarbonate negative topographies used as substrates for the templated selfassembly of microsphere-based microrobots. This approach protects primary structures from damage during molding and de-molding, providing high fidelity negatives of arrays for assembly via templated assembly by selective removal (TASR). We show that reducing the surface energy mismatch between the microspheres and substrate results in yield increases up to 790%. This work addresses yield-related challenges of multicomponent microsystem assembly with existing PDMS-based templated assembly methods. The application of this technology in DNA microswimmer fabrication is demonstrated.

INTRODUCTION

Complex multicomponent microrobots, such as microswimmers, have potential applications in electronics, microfluidic mixing, and targeted drug delivery [1]-[2]. To realize the potential of this technology, fabrication methods must be capable of making large, monodisperse populations of robots. One example of a process to fabricate microswimmers is a hybrid top-down/bottom-up manufacturing process that combines templated assembly by selective removal (TASR) with DNA nanotechnology [3]. In this process, hydrophobic interactions drive the deposition of polystyrene microspheres into size-matched, hemispherical pockets constructed from Polydimethylsiloxane (PDMS). Sonication removes improperly matched particles and DNA nanotubes connect the spheres via biotin-streptavidin binding [3]. Previously, microsphere-based robots were made from random arrangements of particles assembled via one-pot reactions or magnetic manipulation [4]-[5]. TASR improves on these methods by controlling both the size and placement of components during fabrication, resulting in precise assembly of complex, multi-component structures.