A unique evanescent-wave biosensor was designed and fabricated using simple and robust microfabrication technology. The sensor uses a microscale optical waveguide fabricated from NOA61 that is surface-altered with a custom chemical modification process, coupled with modified self-assembly of an oxygen-sensitive fluorescent dye and the enzyme glucose oxidase. To interface the analyte with the waveguide surface, a multilayer PDMS fluidic mold was designed to fit over the waveguide. Interfacing of both optics and fluidics was achieved using novel-generic methods. The entire device has been successfully fabricated and assembled, with analyte response testing completed using glucose solutions. The system also demonstrated inherent random noise insensitivity while making measurements.
A novel PDMS microfluidic spotter system has been developed for the patterning of surface microarrays that require individually addressing each spot area and high probe density. Microfluidic channels are used to address each spot region and large spot arrays can be addressed in parallel. Fluorescence intensity measurement of dye-spotted samples compared to control and pipetted drops demonstrated a minimum of a three-fold increase in dye surface density. Surface plasmon resonance measurement of protein-spotted samples as compared to pin-spotted samples demonstrated an 86-fold increase in protein surface density. This novel spotter system can be applied to the production of high-throughput arrays in the fields of genomics, proteomics, immunoassays and fluorescence or luminescence assays.
This paper describes the design and fabrication of an integrated optical glucose sensing system using the combination of the oxygen sensitive dye tris(2,2’-bipyridyl) dichlororuthenium(II) hexahydrate and glucose oxidase. Layer-by-layer self-assembly is used to immobilize the dye/enzyme system onto the surface of the waveguides. Changes in the enzyme/dye system as it interacts with the surrounding environment are monitored using end-face interaction with light injected into waveguides. The waveguides are thermally-defined monolithic polydimethlysiloxane (PDMS) waveguide system, fabricated on a PDMS substrate. The method of waveguide fabrication is a radical departure from conventional microscale waveguide systems, and offers unique opportunities for integration of this sensor into existing microfluidic systems.
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 the 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. Exposure of the dye molecules to the analyte and subsequent chemical interaction is achieved by directly coupling the fluid channel to the integrated waveguide. 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.