Surface Plasmon Resonance-Based Sensing Utilizing Spatial Phase Modulation in an Imaging Interferometer
Spatial phase modulation in an imaging interferometer is utilized in surface plasmon resonance (SPR) based sensing of liquid analytes. In the interferometer, a collimated light beam from a laser diode irradiating at 637.1 nm is passing through a polarizer and is reflected from a plasmonic structure...
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MDPI AG
2020-03-01
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| Online Access: | https://www.mdpi.com/1424-8220/20/6/1616 |
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| author | Roman Kaňok Dalibor Ciprian Petr Hlubina |
| author_facet | Roman Kaňok Dalibor Ciprian Petr Hlubina |
| author_sort | Roman Kaňok |
| collection | DOAJ |
| description | Spatial phase modulation in an imaging interferometer is utilized in surface plasmon resonance (SPR) based sensing of liquid analytes. In the interferometer, a collimated light beam from a laser diode irradiating at 637.1 nm is passing through a polarizer and is reflected from a plasmonic structure of SF10/Cr/Au attached to a prism in the Kretschmann configuration. The beam passes through a combination of a Wollaston prism, a polarizer and a lens, and forms an interference pattern on a CCD sensor of a color camera. Interference patterns obtained for different liquid analytes are acquired and transferred to the computer for data processing. The sensing concept is based on the detection of a refractive index change, which is transformed via the SPR phenomenon into an interference fringe phase shift. By calculating the phase shift for the plasmonic structure of SF10/Cr/Au of known parameters we demonstrate that this technique can detect different weight concentrations of ethanol diluted in water, or equivalently, different changes in the refractive index. The sensitivity to the refractive index and the detection limit obtained are −278 rad/refractive-index-unit (RIU) and 3.6 <inline-formula> <math display="inline"> <semantics> <mrow> <mo>×</mo> <mspace width="3.33333pt"></mspace> <msup> <mn>10</mn> <mrow> <mo>−</mo> <mn>6</mn> </mrow> </msup> </mrow> </semantics> </math> </inline-formula> RIU, respectively. The technique is demonstrated in experiments with the same liquid analytes as in the theory. Applying an original approach in retrieving the fringe phase shift, we revealed good agreement between experiment and theory, and the measured sensitivity to the refractive index and the detection limit reached −226 rad/RIU and 4.4 <inline-formula> <math display="inline"> <semantics> <mrow> <mo>×</mo> <mspace width="3.33333pt"></mspace> <msup> <mn>10</mn> <mrow> <mo>−</mo> <mn>6</mn> </mrow> </msup> </mrow> </semantics> </math> </inline-formula> RIU, respectively. These results suggest that the SPR interferometer with the detection of a fringe phase shift is particularly useful in applications that require measuring refractive index changes with high sensitivity. |
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| issn | 1424-8220 |
| language | English |
| last_indexed | 2024-04-11T14:07:05Z |
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| spelling | doaj.art-7c9c3ea0dd7b447c83ee529ce6ad11962022-12-22T04:19:51ZengMDPI AGSensors1424-82202020-03-01206161610.3390/s20061616s20061616Surface Plasmon Resonance-Based Sensing Utilizing Spatial Phase Modulation in an Imaging InterferometerRoman Kaňok0Dalibor Ciprian1Petr Hlubina2Department of Physics, Technical University Ostrava, 17. listopadu 2172/15, 708 00 Ostrava-Poruba, Czech RepublicDepartment of Physics, Technical University Ostrava, 17. listopadu 2172/15, 708 00 Ostrava-Poruba, Czech RepublicDepartment of Physics, Technical University Ostrava, 17. listopadu 2172/15, 708 00 Ostrava-Poruba, Czech RepublicSpatial phase modulation in an imaging interferometer is utilized in surface plasmon resonance (SPR) based sensing of liquid analytes. In the interferometer, a collimated light beam from a laser diode irradiating at 637.1 nm is passing through a polarizer and is reflected from a plasmonic structure of SF10/Cr/Au attached to a prism in the Kretschmann configuration. The beam passes through a combination of a Wollaston prism, a polarizer and a lens, and forms an interference pattern on a CCD sensor of a color camera. Interference patterns obtained for different liquid analytes are acquired and transferred to the computer for data processing. The sensing concept is based on the detection of a refractive index change, which is transformed via the SPR phenomenon into an interference fringe phase shift. By calculating the phase shift for the plasmonic structure of SF10/Cr/Au of known parameters we demonstrate that this technique can detect different weight concentrations of ethanol diluted in water, or equivalently, different changes in the refractive index. The sensitivity to the refractive index and the detection limit obtained are −278 rad/refractive-index-unit (RIU) and 3.6 <inline-formula> <math display="inline"> <semantics> <mrow> <mo>×</mo> <mspace width="3.33333pt"></mspace> <msup> <mn>10</mn> <mrow> <mo>−</mo> <mn>6</mn> </mrow> </msup> </mrow> </semantics> </math> </inline-formula> RIU, respectively. The technique is demonstrated in experiments with the same liquid analytes as in the theory. Applying an original approach in retrieving the fringe phase shift, we revealed good agreement between experiment and theory, and the measured sensitivity to the refractive index and the detection limit reached −226 rad/RIU and 4.4 <inline-formula> <math display="inline"> <semantics> <mrow> <mo>×</mo> <mspace width="3.33333pt"></mspace> <msup> <mn>10</mn> <mrow> <mo>−</mo> <mn>6</mn> </mrow> </msup> </mrow> </semantics> </math> </inline-formula> RIU, respectively. These results suggest that the SPR interferometer with the detection of a fringe phase shift is particularly useful in applications that require measuring refractive index changes with high sensitivity.https://www.mdpi.com/1424-8220/20/6/1616surface plasmon resonancekretschmann configurationspatial phase modulationimaging interferometerfringe phase shiftsensitivityaqueous solutions of ethanol |
| spellingShingle | Roman Kaňok Dalibor Ciprian Petr Hlubina Surface Plasmon Resonance-Based Sensing Utilizing Spatial Phase Modulation in an Imaging Interferometer Sensors surface plasmon resonance kretschmann configuration spatial phase modulation imaging interferometer fringe phase shift sensitivity aqueous solutions of ethanol |
| title | Surface Plasmon Resonance-Based Sensing Utilizing Spatial Phase Modulation in an Imaging Interferometer |
| title_full | Surface Plasmon Resonance-Based Sensing Utilizing Spatial Phase Modulation in an Imaging Interferometer |
| title_fullStr | Surface Plasmon Resonance-Based Sensing Utilizing Spatial Phase Modulation in an Imaging Interferometer |
| title_full_unstemmed | Surface Plasmon Resonance-Based Sensing Utilizing Spatial Phase Modulation in an Imaging Interferometer |
| title_short | Surface Plasmon Resonance-Based Sensing Utilizing Spatial Phase Modulation in an Imaging Interferometer |
| title_sort | surface plasmon resonance based sensing utilizing spatial phase modulation in an imaging interferometer |
| topic | surface plasmon resonance kretschmann configuration spatial phase modulation imaging interferometer fringe phase shift sensitivity aqueous solutions of ethanol |
| url | https://www.mdpi.com/1424-8220/20/6/1616 |
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