Design and fabrication of a microfluidic device for near-single cell mRNA isolation using a copper hot embossing master

Abstract

We describe investigations toward a disposable polymer-based chip for the isolation of eukaryotic mRNA. This work focuses here on the improvement of the fabrication methods for rapid prototyping and the actual application at lowest RNA concentrations with total channel volumes of 3.5 lL. Messenger RNA isolation was achieved using paramagnetic oligo (dT) 25 beads within a microfluidic channel which incorporated a sawtooth microstructured design to aid in mixing. The structures were shown to facilitate mixing beteen two fluids in parallel flow when compared to a channel without structures. The chip was fabricated by means of hot embossing poly(methyl methacrylate) (PMMA) using a copper master. Copper was used as the master material due to its excellent thermal, mechanical, and electroplating properties. Fabrication of the master consisted of the structuring of a polished copper plate using KMPR 1050 as an electroplating mold for forming the microchannel structures. The copper master was found to be much more robust than traditional silicon masters used for prototyping. The use of KMPR enabled the generation of high straight walls in contrast to SU-8 masters. In addition, embossing times were able to be decreased by a factor of 3 due to improved heat conduction and avoidance of a lengthy and delicate de-embossing step.

Isolation and Amplification of mRNA within a Simple Microfluidic Lab on a Chip

“…25 The copper template was fabricated at the Cornell Nanoscale Facility (CNF) via photolithography using KMPR 1050 (Micro-Chem Corp., MA) and copper electroplating resulting in elevated channel structures. A 5×5cm piece of PMMA was sandwiched between the copper template and a blank copper plate, and using a hot press (CarverLaminating), the PMMA was patterned at 130°C and 8000 lbs.…”

Quantum dot-linked immunoassay on a PMMA-based microfluidic device for biomarker detection

“…The patterned substrate is then cooled to room temperature and developed for ten minutes in SU-8 developer under manual agitation. [2] Electroplating: Once the SU-8 micropatterned copper substrate (Fig. 1a) has been manufactured copper electroplating is performed to create raised microchannel structures on the copper substrate.…”

Development and characterization of a capillary-flow microfluidic device for nucleic acid detection

“…Microfluidic channels can be formed in substrates such as PMMA using laser ablation (Conlisk et al 2011;Hong et al 2010;Klank et al 2002), hot embossing (Nugen et al 2008) or injection molding (Zhou et al 2005). Laser ablation allows for rapid prototyping as opposed to other methods which require machining of a mold.…”