In this paper poly-(dimethylsiloxane) (PDMS) is introduced as a resist material for proton beam writing. We were looking for a biocompatible micropatternable polymer in which the chemical structure changes significantly due to proton beam exposure making the polymer suitable for proton beam writing. Up to now PDMS has been used as a casting or replicating material in microfabrication to form microchannels, micromolds, microstamps, etc. PDMS has not been used as a resist material for direct write techniques. In this work we investigated the surface topography of the irradiated regions of PDMS under and without stress (on the cut surface and on the original fluid surface, respectively). In the samples wherein stress was not developed, noticeable compaction was observed. In the case of samples wherein stress was developed, noticeable swelling occurred. (c) 2009 Elsevier B.V. All rights reserved.