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Optical Gratings Coated with Thin Si3N4 Layer for Efficient Immunosensing by Optical Waveguide Lightmode Spectroscopy.

Diéguez L, Caballero D, Calderer J, Moreno M, Martínez E, Samitier J - Biosensors (Basel) (2012)

Bottom Line: A thin layer of 10 nm of transparent silicon nitride was deposited on commercial optical gratings by means of sputtering.The quality of the layer was tested by x-ray photoelectron spectroscopy and atomic force microscopy.The potential of the Si3N4 as functional layer in a real-time biosensor opens new ways for the integration of optical waveguides with microelectronics.

View Article: PubMed Central - PubMed

Affiliation: Department of Electronics, University of Barcelona, C/Martí i Franquès 1, Barcelona, ES 08028, Spain. lorena.dieguez@unisa.edu.au.

ABSTRACT
New silicon nitride coated optical gratings were tested by means of Optical Waveguide Lightmode Spectroscopy (OWLS). A thin layer of 10 nm of transparent silicon nitride was deposited on commercial optical gratings by means of sputtering. The quality of the layer was tested by x-ray photoelectron spectroscopy and atomic force microscopy. As a proof of concept, the sensors were successfully tested with OWLS by monitoring the concentration dependence on the detection of an antibody-protein pair. The potential of the Si3N4 as functional layer in a real-time biosensor opens new ways for the integration of optical waveguides with microelectronics.

No MeSH data available.


Related in: MedlinePlus

Atomic Force Microscopy (AFM) images of the grating chip (a) before, (b) after silicon nitride thin layer deposition and (c) after antibody functionalization. The grating structure is maintained after both the silicon nitride thin film and the organic layer deposition.
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biosensors-02-00114-f004: Atomic Force Microscopy (AFM) images of the grating chip (a) before, (b) after silicon nitride thin layer deposition and (c) after antibody functionalization. The grating structure is maintained after both the silicon nitride thin film and the organic layer deposition.

Mentions: Prior to the silicon nitride layer deposition, the grating substrate was characterized by means of atomic force microscopy (AFM). Figure 4(a) shows 2D topography AFM images of the grating and a line profile. As it can be seen, the grating has a period of 450 nm, a grafting apparent depth of around 7 nm and a RMS value on the flat top surfaces of 0.7 nm. Due to the AFM tip convolution, it is likely that the measured depth of the grating is underestimated. After the deposition of the silicon nitride layer, Figure 4(b), it can be noticed that surface roughness has increased up to 2.6 nm (RMS value), presenting a grainier morphology, while the grating structure remained barely altered (period of 450 nm and apparent depth of 7 nm). Once the chip was functionalized with the anti-HSA antibodies, the morphology of the grating was again characterized by the AFM technique. Figure 4(c) shows the changes produced by the organic layer: the grating structure period remains unaltered (450 nm) but the structure depth decreases slightly (5–6 nm) and the surface becomes again smoother, with RMS values around 1.8 nm.


Optical Gratings Coated with Thin Si3N4 Layer for Efficient Immunosensing by Optical Waveguide Lightmode Spectroscopy.

Diéguez L, Caballero D, Calderer J, Moreno M, Martínez E, Samitier J - Biosensors (Basel) (2012)

Atomic Force Microscopy (AFM) images of the grating chip (a) before, (b) after silicon nitride thin layer deposition and (c) after antibody functionalization. The grating structure is maintained after both the silicon nitride thin film and the organic layer deposition.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4263575&req=5

biosensors-02-00114-f004: Atomic Force Microscopy (AFM) images of the grating chip (a) before, (b) after silicon nitride thin layer deposition and (c) after antibody functionalization. The grating structure is maintained after both the silicon nitride thin film and the organic layer deposition.
Mentions: Prior to the silicon nitride layer deposition, the grating substrate was characterized by means of atomic force microscopy (AFM). Figure 4(a) shows 2D topography AFM images of the grating and a line profile. As it can be seen, the grating has a period of 450 nm, a grafting apparent depth of around 7 nm and a RMS value on the flat top surfaces of 0.7 nm. Due to the AFM tip convolution, it is likely that the measured depth of the grating is underestimated. After the deposition of the silicon nitride layer, Figure 4(b), it can be noticed that surface roughness has increased up to 2.6 nm (RMS value), presenting a grainier morphology, while the grating structure remained barely altered (period of 450 nm and apparent depth of 7 nm). Once the chip was functionalized with the anti-HSA antibodies, the morphology of the grating was again characterized by the AFM technique. Figure 4(c) shows the changes produced by the organic layer: the grating structure period remains unaltered (450 nm) but the structure depth decreases slightly (5–6 nm) and the surface becomes again smoother, with RMS values around 1.8 nm.

Bottom Line: A thin layer of 10 nm of transparent silicon nitride was deposited on commercial optical gratings by means of sputtering.The quality of the layer was tested by x-ray photoelectron spectroscopy and atomic force microscopy.The potential of the Si3N4 as functional layer in a real-time biosensor opens new ways for the integration of optical waveguides with microelectronics.

View Article: PubMed Central - PubMed

Affiliation: Department of Electronics, University of Barcelona, C/Martí i Franquès 1, Barcelona, ES 08028, Spain. lorena.dieguez@unisa.edu.au.

ABSTRACT
New silicon nitride coated optical gratings were tested by means of Optical Waveguide Lightmode Spectroscopy (OWLS). A thin layer of 10 nm of transparent silicon nitride was deposited on commercial optical gratings by means of sputtering. The quality of the layer was tested by x-ray photoelectron spectroscopy and atomic force microscopy. As a proof of concept, the sensors were successfully tested with OWLS by monitoring the concentration dependence on the detection of an antibody-protein pair. The potential of the Si3N4 as functional layer in a real-time biosensor opens new ways for the integration of optical waveguides with microelectronics.

No MeSH data available.


Related in: MedlinePlus