An integrated optical oxygen sensor fabricated using rapid-prototyping techniques

Abstract

This paper details the design and fabrication of an integrated optical biochemical sensor using a select oxygen-sensitive fluorescent dye, tris(2,2'-bipyridyl) dichlororuthenium(ii) hexahydrate, combined with polymeric waveguides that are fabricated on a glass substrate. The sensor uses evanescent interaction of light confined within the waveguide with the dye that is immobilized on an SU-8 waveguide surface. Adhesion of the dye to the integrated waveguide surface is accomplished using a unique process of spin-coating/electrostatic layer-by-layer formation. The SU-8 waveguide was chemically modified to allow the deposition process. Exposure of the dye molecules to the analyte and subsequent chemical interaction is achieved by directly coupling the fluid channel to the integrated waveguide. The completed sensor was linear in the dissolved oxygen across a wide range of interest and had a sensitivity of 0.6 ppm. A unique fabrication aspect of this sensor is the inherent simplicity of the design, and the resulting rapidity of fabrication, while maintaining a high degree of functionality and flexibility.

Development of an integrated microfluidic platform for dynamic oxygen sensing and delivery in a flowing medium

“…By monitoring the inlet and outlet gas concentration at various flow rates, the mass transfer characteristics of the device were characterized as a function of an effective dimensionless oxygenator ''length''. While previous work has demonstrated optical sensing of gaseous oxygen 9,11 and sensing of static fluids in biological microenvironments, 7,8,12 the application of an integrated optical sensor for detection of dissolved oxygen in a flowing medium with active mass transfer is a unique development. A micro-device capable of oxygen sensing and delivery provides the potential for closedloop control and regulation of biochemical species, a particularly important and unique development for the types of biological micro-device and tissue engineering applications previously reported in literature.…”

“…These ideal characteristics have generated intense interest in luminescent chemical sensors, which have been demonstrated and marketed in a variety of configurations for various biological, environmental, aerospace, and other applications. 2,[6][7][8][9][10][11][12][13][14][15] With the specific intent of meeting the challenge of low-cost and ease-of-fabrication gas sensors, we report on the development of a luminescent oxygen sensor incorporated into a microfluidic oxygenation platform. Optical oxygen detection is achieved through the excitation of a luminescent dye suspended in a microporous polymer matrix.…”

“…The resolution and accuracy of the sensor for detection of both gaseous samples and fluidic samples compares favorably with results previously demonstrated. 11,12 The range and resolution of the sensor make it ideally suited to detection of dissolved oxygen in biological fluids such as blood.…”

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

“…When exposed to organic matter, sensor lifetime has been found to decrease through membrane fouling, while additional problems are posed by miniaturization itself, mainly due to the need for a reference electrode and the depletion of analyte by the underlying sensing reaction. 8 By contrast, fluorescent dye-based optical sensing does not exhibit analyte depletion, and has therefore emerged as a promising alternative in biomedical applications. While oxygen quenching is exhibited by the majority of fluorescent dyes, a smaller subgroup has been found to be especially suited and is used in solution 6,11,12 or immobilized on a support matrix 8,13-16 for the detection of DO.…”

“…This is a particular problem for sensing of less stable solutes such as oxygen, where retrieval is likely to significantly alter the sample. 8 Alternative in-situ sensor technologies are therefore needed and we report on the patterning, integration and characterisation of such a sensor.…”