Fabrication of nanofluidic devices using electrochemical etching of sacrificial copper

Micro- and nanoscale mechanical systems provide unique capabilities for analyzing fluid samples in chemical and biological research. A method of creating nanofluidic systems with integrated sensor electrodes is presented with a detailed description of the fabrication process. Devices were built by creating nanometer scale copper channels on glass substrates and patterning gold cross channels above the copper. The metal layers were then enclosed in a polymer layer with openings at the end of each channel. The copper layer was then dissolved using chemical etching, leaving an open channel with embedded gold electrodes. The majority of this work focuses on describing the metal etching process. All of the etching was performed by electrochemical dissolution of the copper, where an external electrical potential is applied to the sacrificial layer to accelerate the process. The electrochemical etching allows channels several hundred microns long to be created in approximately 20 minutes, compared to conventional chemical etching which will take several days. Etching rates are determined for various widths and thicknesses of the channel, as well as the dependence on the applied voltage. Copper sulfate and copper nitrate are evaluated as possible etchant solutions, with sulfuric and nitric used to adjust the pH. Experimental etch rates are presented and compared to theoretical approximations based on the Poisson-Boltzmann and Nernst-Plank transport equation. Methods to minimize potential problems such as channel collapse and material debris are also discussed. The finished nanofluidic devices, as well as the etching process itself, provide new tools for studying mass and charge transport at the nanoscale.

Name thesis:degree_name

M.S.

Level thesis:degree_level

Thesis

Discipline thesis:degree_discipline

Mechanical Engineering

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2010

Author dc:creator

• Sawyer, Adam R.

Contributors dc:contributor

• Shannon, Mark A.

• electrochemical etching
• copper etching
• microfluidics
• nanofluidics

Statement dc:rights

• Copyright 2010 Adam R. Sawyer

Language dc:language

en

Handle dc:identifier

http://hdl.handle.net/2142/16235

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/16235