Project Dissemination
Poster Presentation at international conference:
Swiss-@Print - The First Swiss Conference on Printed Electronics and Functional Materials, Basel, Switzerland, December 1-2, 2011.
http://www.swiss-eprint.ch/
Pad printing microelectrode arrays onto a porous polymer membrane: a promising low cost fabrication process.
Philippe Passeraub 1, Fabien Moreillon 1, David Hakkoum 2, Luc Stoppini 2, Marc Olivier Heuschkel 3
1 University of Applied Sciences of Western Switzerland (HES-SO/hepia Geneva), Bioinstrumentation Microengineering Laboratory.
2 University of Applied Sciences of Western Switzerland (HES-SO/hepia Geneva), Tissue Engineering Laboratory.
3 Ayanda Biosystems SA, Lausanne, Switzerland.
Abstract
Microelectrode arrays (MEAs) are used in biology and medical research for the stimulation and the recording of bioelectrical signals of in vitro cultures of excitable cells or tissues. Such in vitro tests are of high interest to replace animal experiments in toxicology assessments. For this application high-throughput screening techniques permit to increase productivity. However it requires an increasing number of low cost disposable devices. Typically MEAs are being fabricated in batches using various processes including photolithography steps. Nevertheless for practical reasons resulting from the application the size of MEAs cannot be miniaturized. Consequently the benefit of the batch approach is limited and the overall fabrication effort is considerable.
Porous polymer membranes are a promising substrate for new generations of MEAs since it provides a higher flexibility for biologists in cultures and in protocols. However it increases the complexity when using conventional microfabrication steps because of the pores. Either additional steps are needed to obtain the pores or, a porous polymer with specific constraints (e.g. limited temperature or poor compatibility with clogging steps like photolithography) has to be used as substrate.
Pad printing is a mature technology used in the industry for printing inks and a range of other materials onto different kinds of substrate, like watch dials, golf balls, or medical devices. It is also used to print functional RF antennas for mobile phones or electrical connections for solar cells using conductive inks. This technique allows the printing of any kind of pattern on top of non-flat surfaces. Also successive well-aligned printing steps make it possible to obtain complex multilayer patterns.
We report successful results in fabricating MEAs using the pad printing of a conductive and a non-conductive ink on a porous polymer membrane. Lines down to 50 m width have been printed. Low resistivity of 0.4 / is achieved. Biocompatibility of the obtained MEAs has been demonstrated. Furthermore first bioelectrical signals from cultured hippocampal brain slices have been recorded successfully with such devices. We present a comparison between pad printed MEAs and polyimide-based microfabricated MEAs having similar pattern. Pad printed MEAs do have a lower resolution but are fabricated much faster and with less effort. It results that pad printing is a promising and well-suited fabrication process for obtaining low cost MEAs devices.
The research leading to these results has received funding from the European Community’s Seventh Framework Program [FP7/2007-2013] under grant agreement n°232554.