Photolithographic patterning of polymer-encapsulated optical oxygen sensors

In this paper we show a novel fabrication process capable of yielding arbitrarily-shaped optical oxygen sensor patterns at micron resolution. The wafer-level process uses a thin-film sacrificial metal layer as intermediate mask, protecting the sensor material and enabling the use of conventional semiconductor patterning techniques. Feature sizes down to 3 pm are demonstrated and only limited by the lithographic process. Gaseous oxygen detection using the patterned sensors shows Stern-Volmer behaviour with a measured intensity ratio I(100)/I(0) of 10.8, the highest reported for a lab-on-a-chip compatible glass substrate. The process has the potential to enable the integration of multiple sensor patches underneath single cells for laterally registered oxygen sensing in cell-culture applications. (C) 2009 Elsevier B.V. All rights reserved.