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Evanescent field Sensors Based on Tantalum Pentoxide Waveguides – A Review

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ABSTRACT

Evanescent field sensors based on waveguide surfaces play an important role where high sensitivity is required. Particularly tantalum pentoxide (Ta2O5) is a suitable material for thin-film waveguides due to its high refractive index and low attenuation. Many label-free biosensor systems such as grating couplers and interferometric sensors as well as fluorescence-based systems benefit from this waveguide material leading to extremely high sensitivity. Some biosensor systems based on Ta2O5 waveguides already took the step into commercialization. This report reviews the various detection systems in terms of limit of detection, the applications, and the suitable surface chemistry.

No MeSH data available.


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(a) Schematic of the input grating coupler instrument. In an angular scan, the TE0 and TM0 modes are successively excited by an s- and a p-polarized laser beam. L = lever arm; MS = micrometer screw; SM = stepping motor; Cu = cuvette; Laser = He-Ne laser (λ = 632.8 nm); FP = Foster prism; M1 and M2 = mirrors; P = incident power; P′ = power of incoupled guided mode; α = angle of incidence; D1 and D2 = silicon photodetectors. (b) Detailed view of the sensor: C = liquid cover; F = waveguiding film of thickness dF on glass substrate S. From [34], Copyright Elsevier (1990).
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f5-sensors-08-00711: (a) Schematic of the input grating coupler instrument. In an angular scan, the TE0 and TM0 modes are successively excited by an s- and a p-polarized laser beam. L = lever arm; MS = micrometer screw; SM = stepping motor; Cu = cuvette; Laser = He-Ne laser (λ = 632.8 nm); FP = Foster prism; M1 and M2 = mirrors; P = incident power; P′ = power of incoupled guided mode; α = angle of incidence; D1 and D2 = silicon photodetectors. (b) Detailed view of the sensor: C = liquid cover; F = waveguiding film of thickness dF on glass substrate S. From [34], Copyright Elsevier (1990).

Mentions: Along with further developments of the input grating coupler, this detection limit could be gradually improved and several chemo- and immunoassays performed by Nellen and Lukosz [32, 34]. Fig. 5 shows schematically the basic setup of an input grating coupler sensor. To excite TE0 and TM0 modes in the waveguide, an s- and a p-polarized laser beam (corresponding to TE and TM) are scanned at a variable angle, which depends on the surface mass coverage and thereby the effective refractive index. Two photodetectors mounted on a rotation stage detect the signal, rendering the mechanical setup demanding. The grating requires a highly precise mechanical movement of the rotation stage including waveguide sensor and fluidic parts.


Evanescent field Sensors Based on Tantalum Pentoxide Waveguides – A Review
(a) Schematic of the input grating coupler instrument. In an angular scan, the TE0 and TM0 modes are successively excited by an s- and a p-polarized laser beam. L = lever arm; MS = micrometer screw; SM = stepping motor; Cu = cuvette; Laser = He-Ne laser (λ = 632.8 nm); FP = Foster prism; M1 and M2 = mirrors; P = incident power; P′ = power of incoupled guided mode; α = angle of incidence; D1 and D2 = silicon photodetectors. (b) Detailed view of the sensor: C = liquid cover; F = waveguiding film of thickness dF on glass substrate S. From [34], Copyright Elsevier (1990).
© Copyright Policy
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC3927514&req=5

f5-sensors-08-00711: (a) Schematic of the input grating coupler instrument. In an angular scan, the TE0 and TM0 modes are successively excited by an s- and a p-polarized laser beam. L = lever arm; MS = micrometer screw; SM = stepping motor; Cu = cuvette; Laser = He-Ne laser (λ = 632.8 nm); FP = Foster prism; M1 and M2 = mirrors; P = incident power; P′ = power of incoupled guided mode; α = angle of incidence; D1 and D2 = silicon photodetectors. (b) Detailed view of the sensor: C = liquid cover; F = waveguiding film of thickness dF on glass substrate S. From [34], Copyright Elsevier (1990).
Mentions: Along with further developments of the input grating coupler, this detection limit could be gradually improved and several chemo- and immunoassays performed by Nellen and Lukosz [32, 34]. Fig. 5 shows schematically the basic setup of an input grating coupler sensor. To excite TE0 and TM0 modes in the waveguide, an s- and a p-polarized laser beam (corresponding to TE and TM) are scanned at a variable angle, which depends on the surface mass coverage and thereby the effective refractive index. Two photodetectors mounted on a rotation stage detect the signal, rendering the mechanical setup demanding. The grating requires a highly precise mechanical movement of the rotation stage including waveguide sensor and fluidic parts.

View Article: PubMed Central - PubMed

ABSTRACT

Evanescent field sensors based on waveguide surfaces play an important role where high sensitivity is required. Particularly tantalum pentoxide (Ta2O5) is a suitable material for thin-film waveguides due to its high refractive index and low attenuation. Many label-free biosensor systems such as grating couplers and interferometric sensors as well as fluorescence-based systems benefit from this waveguide material leading to extremely high sensitivity. Some biosensor systems based on Ta2O5 waveguides already took the step into commercialization. This report reviews the various detection systems in terms of limit of detection, the applications, and the suitable surface chemistry.

No MeSH data available.


Related in: MedlinePlus