Volume 4 • Issue 2 • 1000e120 J Biosens Bioelectron ISSN: 2155-6210 JBSBE, an open access journal Research Article Open Access Magnusson, J Biosens Bioelectron 2013, 4:2 DOI: 10.4172/2155-6210.1000e120 *Corresponding author: Robert Magnusson, Department of Electrical Engineering, University of Texas at Arlington, Resonant Sensors Incorporated, Arlington, Texas, USA, E-mail: magnusson@uta.edu Received May 20, 2013; Accepted May 21, 2013; Published May 22, 2013 Citation: Magnusson R (2013) The Complete Biosensor. J Biosens Bioelectron 4: e120. doi:10.4172/2155-6210.1000e120 Copyright: © 2013 Magnusson R. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. The Complete Biosensor Robert Magnusson* Department of Electrical Engineering, University of Texas at Arlington; Resonant Sensors Incorporated, Arlington, Texas, USA Design and fabrication of nanostructured sensors based on optical, electrical, or mechanical principles has advanced tremendously in the last decade. Tis is due in part to progress in numerical design tools, computational power and nanofabrication capability. Across the globe, there is growing interest in advanced sensor technologies for diverse applications in homeland security, biomedicine, drug development, food safety and environmental monitoring. Tese sensor systems must be portable and cost-efective, while providing rapid response with high sensitivity, reliability and minimal false-reading counts. Most biosensor technologies currently available employ fuorescent or absorption labeling to register a specifc biomolecular reaction. For reasons of expense and expediency, there is increasing demand for improved sensor techniques that do not require labeling. In this editorial, we briefy discuss advanced guided-mode resonance (GMR) biosensor technology meeting these demands. Since these sensors can be designed to resonate in multiple modes, complete information about a bioreaction can be extracted, including the biolayer thickness, biolayer refractive index, and the change in the background solution refractive index. Tus, justifably, we refer to this sensor as the complete biosensor. Te resonance frequency of the GMR device varies as any of its structural parameters change. In a biomolecular binding event, an attaching biolayer alters the efective thickness of the resonant layer afecting the resonance wavelength. Tis is shown schematically in fgure 1. Te wavelength change can be monitored with a spectrum analyzer in real time to quantify the binding dynamics. A wide variety of sensor geometries, materials and system architectures can be implemented. To provide a historical perspective, in 1992, Magnusson and Wang [1] suggested application of the GMR efect to sensors and disclosed GMR flters that were tunable on variation in resonance structure parameters, including thickness and refractive index [2]. Wawro et al. [3] presented new GMR biosensor embodiments, as well as new applications of these sensors when integrated with optical fbers. Te use of modal and polarization diversity for multi parametric biosensors is a particularly interesting aspect of this technology [4]. Applying the GMR concept, we have developed and verifed a new foundational methodology for biosensing that is robust against false readings. We employ modal and polarization-based parametric discrimination. Our resonant sensors are designed to support two or more leaky optical modes in the spectral band of interest. Tese modes can be directly excited with a beam of unpolarized light as they resonate in their respective polarization states. Tis property provides enriched data sets that can be used to calibrate simultaneously for variations such as temperature or sample background density, in the same sensor element, thus increasing detection accuracy and reducing probability of false readings. Concurrent, co-localized data acquisition via such polarization and modal diversity eliminates errors associated with the use of separate reference sites. Our sensors can be arrayed into high- density (~ 10,000 sensors/cm 2 ) platforms that are easily interrogated with a single beam of light. Tey are extremely economic in fabrication and amenable to mass production. Tis important sensor technology will fnd increasing application, for example, in medical diagnostics and drug development. Applying this concept, fgure 2 shows an example set of resonance peaks for a typical sensor. All four peaks can be monitored conveniently in real time using a spectrum analyzer. In an example experiment, we monitor the TE 0 and TM 0 peaks at an identical physical location on the sensor surface. Te objective is Sample Fluid Incident Broadband Light Reflected Narrowband Light Sensor Analyte Antibody Figure 1: A guided-mode resonance sensor schematic. 0.75 0.8 0.85 0.9 0.95 1 0 0.2 0.4 0.6 0.8 1 λ  µ m Reflectance TE 0 TM 1 TM 0 TE 1 Figure 2: Computed resonance spectra for a representative dielectric GMR sensor operating in an aqueous environment. Two resonance peaks associated with the lowest waveguide modes for each polarization state appear. Journal of Biosensors & Bioelectronics J o u r n a l o f B i o s e n s s o r & B i o e l e c t r o n i c s ISSN: 2155-6210