Optical waveguides are proving to be an optimal platform for on-the-spot biosensors. Optical signal transduction provides high discrimination, where even a single fluorescent molecule can be detected. The use of evanescent wave illumination, where the light field extends a fraction of the wavelength above a sensor surface, provides a clean signal for surface reactions with minimal background. By only illuminating a volume extending above the surface by a few hundred nanometers, evanescent wave sensors often don’t require wash steps or other sample processing complexities. The cost of optical technology has been reduced considerably over the past decade with the explosion of digital imaging. All of these factors combine to make for a very practical biosensor design. We will present the architecture and design features of the MBio Diagnostics LightDeck® evanescent planar waveguide sensor, and two of the applications where these practical features enable commercial devices: testing for antibiotic residues in milk, and tests to manage sepsis.
Antibiotic residue testing in milk products is widely performed and requires prompt results on-site at a dairy processor. The cost constraints are quite severe. We detail the approach using waveguide sensors, and present data on residue testing. In a second application, sepsis presents a complex disease state that requires a number of results in real time. With multiple biomarkers, and often algorithmic approaches to analysis, a multiplex platform is essential to delivering the necessary data on-the-spot. We detail host response biomarker panels with applications in risk stratification and therapy optimization.
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