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Proceedings Paper

Integrated optical silicon IC compatible nanodevices for biosensing applications
Author(s): Laura M. Lechuga; Borja Sepulveda; Andreu Llobera; Ana Calle; Carlos Manuel Dominguez
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Paper Abstract

Biological and chemical sensing is one of the application fields where integrated optical nanodevices can play an important role [1]. We present a Silicon Integrated Mach-Zehnder Interferometer Nanodevice using a Total Internal Refraction waveguide configuration. The induced changes due to a biomolecular interactions in the effective refractive index of the waveguide,is monitored by the measurement of the change in the properties of the propagating light. For using this device as a biosensor, the waveguides of the structure must verify two conditions: work in the monomode regime and to have a Surface Sensivity as high as possible in the sensing arm. The MZI device structure is: (i) a Si wafer with a 500 mm thickness (ii) a 2 mm thick thermal Silicon-Oxide layer with a refractive index of 1.46 (iii) a LPCVD Silicon Nitride layer of 100 nm thickness and a refractive index of 2.00, which is used as the guiding layer. To achieve monomode behavior is needed to define a rib structure, with a depth of only 3 nm, on the Silicon Nitride layer by a lithographic step. This rib structure is performed by RIE and is the most critical step in the microfabrication of the device. Over the structure a protective layer of LPCVD SiO2 is deposited, with a 2 mm thickness and a refractive index of 1.46, which is patterned (photolithography) and etched (RIE) to define the sensing arm. The high sensivity of these devices makes them quite suitable for biosensing applications. For that, without loosing their activity the receptors biomolecules are covanlently immobilized, at nanometer scale , on the sensor area surface. Biospecific molecular recognition takes places when the complementary analyte to the receptor is flowed over the receptor using a flow system. Several biosensing applications have been performed with this device as enviromental pollutant control, immunosensing or genetic detection.

Paper Details

Date Published: 18 April 2003
PDF: 9 pages
Proc. SPIE 5119, Bioengineered and Bioinspired Systems, (18 April 2003); doi: 10.1117/12.497470
Show Author Affiliations
Laura M. Lechuga, IMM-Ctr. Nacional de Microelectronica (Spain)
Borja Sepulveda, IMM-Ctr. Nacional de Microelectronica (Spain)
Andreu Llobera, IMB-Ctr. Nacional de Microelectronica (Spain)
Ana Calle, IMM-Ctr. Nacional de Microelectronica (Spain)
Carlos Manuel Dominguez, IMB-Ctr. Nacional de Microelectronica (Spain)

Published in SPIE Proceedings Vol. 5119:
Bioengineered and Bioinspired Systems
Angel Rodriguez-Vazquez; Derek Abbott; Ricardo Carmona, Editor(s)

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