Angularly resolved ellipsometric optical biosensing by means of Bloch surface waves

Abstract

In label-free biosensing, a continuous improvement of the limit of detection is necessary to resolve the small change of the surface refractive index produced by interacting biomolecules at a very small concentration. In the present work, optical sensors based on one-dimensional photonic crystals supporting Bloch surface waves are proposed and adopted for label-free optical biosensing. We describe the implementation of an angularly resolved ellipsometric optical sensing scheme based on Bloch surface waves sustained by tantala/silica multilayers. The angular operation is obtained using a focused beam at fixed wavelength and detection of the angular reflectance spectrum by means of an array detector. The results show that the experimental limit of detection for a particular photonic crystal design is 6.5 × 10(-7) refractive index units (RIU)/Hz(1/2) and further decrease could be obtained. For the first time, we report on the practical application of this technique to a cancer biomarker protocol that aims at the detection of a specific glycoprotein (angiopoietin 2) involved in angiogenesis and inflammation processes.

Label-Free Detection of Tumor Angiogenesis Biomarker Angiopoietin 2 Using Bloch Surface Waves on One Dimensional Photonic Crystals

“…In the present work, the 1-DPC were deposited on standard microscope slides (Menzel). The complex refractive indices of the dielectric materials were determined either by reflection/transmission spectroscopy on single supported thin films or by ellipsometry on test multilayers sustaining BSW to be n SiO2 = 1.474 + i5 × 10 −6 , n Ta2O5 = 2.160 + i5 × 10 −5 , and n TiO2 = 2.28 + i1.8 × 10 −3 at the chosen wavelength of operation λ 0 = 670 nm [12].…”

“…Surface plasmon resonance (SPR), operating in a variety of configurations, is commonly used in biology and pharmaceutical laboratories [3]. Among other label-free optical approaches [4]- [6] those based on the excitation of electromagnetic modes (Bloch surface waves-BSW) at the truncation edge of one dimensional photonic crystals (1-DPC) [7] were proposed and demonstrated as a practical route to enhanced resolution and constitute an attractive alternative to surface plasmon polaritons (SPP) [8]- [12].…”

Biosensing platform combining label-free and labelled analysis using Bloch surface waves

“…Using such values enables one to optimize the stacks according to the considerations published elsewhere 9 . The final structure of the stack is shown in Figure 2 and has been previously applied for an ellipsometric sensing approach 16 . In this stack, a 20 nm thin TiO 2 layer is combined with a periodic SiO 2 / Ta 2 O 5 stack comprising 275 nm and 120 nm thicknesses, respectively.…”

Optical Effects Induced by Bloch Surface Waves in One-Dimensional Photonic Crystals

“…The dispersion law of the BSWs can be chosen in wide spectral range from UV to IR by changing the photonic crystal parameters [6,7]. High sensitivity of the BSWs to boundary conditions provides the possibility to use them as bio-and gas sensors [8][9][10][11][12][13]. Another promising area of application of the BSWs is the development of photonic devices for optoelectronic integrated circuits.…”