title: Patterning, integration and characterisation of polymer optical oxygen sensors for microfluidic devices.
abstract: This paper describes a process for the layer-by-layer fabrication and integration of luminescent dye-based optical oxygen sensors into microfluidic devices. Application of oxygen-sensitive platinum(ii) octaethylporphyrin ketone fluorescent dye dissolved in polystyrene onto glass substrates by spin-coating was studied. Soft lithography with polydimethylsiloxane (PDMS) stamps and reactive ion etching in oxygen plasma were used to produce sensor patterns with a minimum feature size of 25 microm. Sensors patterns were integrated into a PDMS microfluidic device by plasma bonding. No degradation of the sensor response as a result of the lithography and pattern-transfer processes was detected. Gaseous and dissolved oxygen (DO) detection was characterised using fluorescence microscopy. The intensity signal ratio of the sensor films was found to increase almost two-fold from 3.6 to 6.8 by reducing film thickness from 1.3 microm to 0.6 microm. Calibration of DO measurement showed linear Stern-Volmer behaviour that was constant for flow rates from 0.5 to 2 mL min(-1). The calibrated sensors were subsequently used to demonstrate laterally resolved detection of oxygen inside a microfluidic channel. The fabrication process provides a novel, easy to use method for the repeatable integration of optical oxygen sensors into cell-culture and lab-on-a-chip devices.
authors.affiliation: MacDiarmid Institute for Advanced Materials and Nanotechnology, Department of Electrical and Computer Engineering, University of Canterbury, Private Bag 4800, Christchurch, New Zealand. volker.nock@elec.canterbury.ac.nz
authors.forename: Volker
authors.initials: V
authors.lastname: Nock
authors.forename: Richard J
authors.initials: RJ
authors.lastname: Blaikie
authors.forename: Tim
authors.initials: T
authors.lastname: David
mesh_terms: D004129:Dimethylpolysiloxanes / Q000737:chemistry*; D046210:Microfluidic Analytical Techniques / Q000295:instrumentation* / Q000379:methods*; D010100:Oxygen / Q000032:analysis*; D011137:Polystyrenes / Q000737:chemistry*
chemical_list: D004129:Dimethylpolysiloxanes; D011137:Polystyrenes; D010100:Oxygen