An Automated Stage for Scalable Imprinting of DNA Nanowires Based on a Self-Aligning Technique

Abstract

Molecular combing is an established technique for aligning DNA nanowires on a surface. When performed on micro-patterned surfaces, this technique can be used to reliably align and stretch DNA nanowires across micro pillars. Imprinting of these aligned DNA nanowires is an affordable technique for fabrication of arrays of nano-scale channels across micro-scale reservoirs. In the past, DNA combing and imprinting (DCI) have been performed manually to fabricate polymer chips that are used in biomedical applications such as gene therapy and drug delivery studies. Automation of the DCI process is necessary to improve the yield and to scale-up production for these applications. However, existing automated techniques are not appropriate for DNA nano wire imprinting because these techniques cannot handle (i) fragile stamps and (ii) individual chip scale stamps of size ∼1 cm2. Herein, we present the design, fabrication and performance evaluation of an imprinting stage that enables (i) handling fragile stamps via low-cost equipment and (ii) production scale-up via simultaneous handling of multiple stamps. The stage is based on a self-aligning imprinting technique that passively aligns a stamp parallel to the substrate thereby enabling simultaneous imprinting of multiple stamps via a single stage. This self-alignment technique minimizes nano wire breakage by ensuring (i) minimal in-plane stamp motion during imprinting and (ii) that the contact forces do not exceed the weight of the stamp. Based on this technique we have designed/fabricated a stage that can simultaneously handle three stamps and is capable of further scale-up. The stage consists of a movable platform that is mounted on linear bearings and is actuated via a stepper motor. Stamps are loaded onto a holder that is mounted on the movable platform via kinematic couplings. This allows one to rapidly attach and detach the holder from the stage and also makes it possible to handle fragile stamps during loading/unloading. Imprinting of DNA nanowires with a manual stage has demonstrated the feasibility of the self-alignment scheme. Experiments that were performed to test the alignment capability of the stage verify that conformal stamp contact can be achieved across all three stamps even in the presence of an angular misalignment of 5obetween the stamp and the glass slide. This ability to simultaneously align multiple stamps is a critical step in being able to scale-up and fully automate the DCI process. Copyright © 2012 by ASME.