Patterning, integration and characterisation of polymer optical oxygen sensors for microfluidic devices

• Published in: Lab on a chip 2008-08, Vol.8 (8), p.1300-1307
• Main Authors: Nock, Volker, Blaikie, Richard J, David, Tim
• Format: Article
• Language: English
• Subjects: Dimethylpolysiloxanes - chemistry; Microfluidic Analytical Techniques - instrumentation; Microfluidic Analytical Techniques - methods; Oxygen - analysis; Polystyrenes - chemistry
• ISSN: 1473-0197; 1473-0189
• DOI: 10.1039/b801879k

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.