Hallynck, Elewout

Ghent University Academic Bibliography

Photonic biosensor in the angular spectrumElewout HallynckSupervisor(s): Peter BienstmanI. INTRODUCTIONReliable and cost effective biosensors playan important role in medical and biologicalsectors (e.g. pathogenic diagnosis). Most ofthese sensors operate using electronics but inrecent years there has been a lot of researchon photonics based biosensors [1]. In this fieldalone already a lot of different sensor conceptshave been demonstrated. There is however stillroom for innovation as in this paper we presenta novel photonics based biosensor [2]. The ba-sic idea behind photonic biosensors is that thebinding of biomolecules to the sensor inducesa refractive index change which can in turn bequantitatively measured.II. SENSOR CONCEPTThe sensor presented here is based on pho-tonic crystals (PhCs). A photonic crystal is de-fined by a periodic refractive index profile (seeFigure 1) and can be used to diffract light undera certain angle as can be seen in Figure 1.qfFigure 1. For certain wavelengths the incident lighton the photonic crystal will be diffracted out ofthe plane.—————————————————–E. Hallynck is with the Department of In-formation Technology (INTEC), Ghent Univer-sity (UGent), Gent, Belgium. E-mail: Ele-wout.Hallynck@intec.ugent.be .When we look at the pattern of the diffractedlight in the angular spectrum we can distin-guish a Lorentzian shape (see Figure 2). Theposition of this peak is influenced by the refrac-tive index in the PhC and can as a consequencebe used for sensing. Simulations have shownthat shifts of 65 degrees per refractive indexunit and more are possible. A major advan-tage of this sensor over others is that it is ableto operate at a single wavelength where othersensors usually require a wavelength range tooperate.-45 0 45 90-90q (degrees)Data 1.33Data 1.38Lorentzian fit 1.33Lorentzian fit 1.38Figure 2. The Lorentzian peak in the angular spec-trum shifts under influence of the refractive in-dex.III. CONCLUSIONSWe have demonstrated a novel photoniccrystal based sensor that can achieve sensitivi-ties of 65 degrees per refractive index unit andmore. Furhtermore, this sensor only needs asingle wavelength source to operate.REFERENCES[1] X. Fan, I. M. White, S. I. Shopova, H. Zhu, J.D. Suter and Y. Sun, Sensitive optical biosen-sors for unlabeled targets: A review, Anal. Chim.Acta 620, 8-26 (2008).[2] E. Hallynck and P. Bienstman, Photonic crystalbiosensor based on angular spectrum analysis,Optics Express, 18(17), p.18164-18170 (2010).

Photonic biosensor in the angular spectrum

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Photonic biosensor in the angular spectrum

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Ghent University Academic Bibliography