An interferometric biosensor composed of a prism-chamber assembly and a composite waveguide with a Ta2O5 nanometric layer
✍ Scribed by Dan-feng Lu; Zhi-mei Qi; Rui-peng Liu
- Publisher
- Elsevier Science
- Year
- 2011
- Tongue
- English
- Weight
- 758 KB
- Volume
- 157
- Category
- Article
- ISSN
- 0925-4005
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✦ Synopsis
A highly sensitive integrated polarimetric interferometer biosensor with improved long-time stability and simple operation was prepared by using a novel prism-chamber assembly and an inexpensive waveguide made by sputtering a tapered nanometric layer of Ta 2 O 5 on a single-mode glass waveguide. By comparing the measured refractive-index (RI) sensitivities with those simulated based on a four-layer homogeneous waveguide, both the equivalent thicknesses (T eq ) for the tapered Ta 2 O 5 layers and a severe dependence of RI sensitivity on T eq were obtained. Addition of 1 g of water in 100 g of a Chinese liquor (alcohol concentration = 46% (v/v)) was easily detected by the sensor. Monitoring of anti-human IgG adsorption with a waveguide of T eq = 31.99 nm indicates that the antibody coverage required for inducing a phase-different change of = is less than 0.012 monolayer. The same waveguide presents a quasilinear dependence of on water temperature with the slope of d( )/dT = -28.50 • / • C to which the contribution by the thermo-optical effect of the waveguide is 4.24 • / • C, equivalent to a liquid RI change of n c = 1.41 × 10 -5 . The interferometer exhibits the promising potential for chemical and biological analyses because of its outstanding characteristics.