Abstract

We demonstrate label-free optical biosensing using a horizontal air-slotted silicon-rich silicon nitride (SiNx) microdisk resonator. Due to the strong confinement of light in the air-slot, a large resonance shift of 6.2 nm is observed upon reaction of the biotin-functionalized disk with a streptavidin solution with concentration of 2.5 μg/ml. Assuming a linear relationship between resonance shift and streptavidin concentration, we estimate the sensitivity to be 2.5 ± 0.2 nm/(μg/ml). Comparing this value with surface sensitivity of 5.7 nm/nm calculated using FDTD simulations, a detection limit of 30 ± 2 ng/ml, is extrapolated.

© 2010 OSA

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  1. X. Fan, I. M. White, S. I. Shopova, H. Zhu, J. D. Suter, and Y. Sun, “Sensitive optical biosensors for unlabeled targets: a review,” Anal. Chim. Acta 620(1-2), 8–26 (2008).
    [CrossRef] [PubMed]
  2. A. Densmore, M. Vachon, D. X. Xu, S. Janz, R. Ma, Y. H. Li, G. Lopinski, A. Delâge, J. Lapointe, C. C. Luebbert, Q. Y. Liu, P. Cheben, and J. H. Schmid, “Silicon photonic wire biosensor array for multiplexed real-time and label-free molecular detection,” Opt. Lett. 34(23), 3598–3600 (2009).
    [CrossRef] [PubMed]
  3. K. De Vos, I. Bartolozzi, E. Schacht, P. Bienstman, and R. Baets, “Silicon-on-Insulator microring resonator for sensitive and label-free biosensing,” Opt. Express 15(12), 7610–7615 (2007).
    [CrossRef] [PubMed]
  4. V. R. Almeida, Q. Xu, C. A. Barrios, and M. Lipson, “Guiding and confining light in void nanostructure,” Opt. Lett. 29(11), 1209–1211 (2004).
    [CrossRef] [PubMed]
  5. G. S. Wiederhecker, C. M. B. Cordeiro, F. Couny, F. Benabid, S. A. Maier, J. C. Knight, C. H. B. Cruz, and H. L. Fragnito, “Field enhancement within an optical fibre with a subwavelength air core,” Nat. Photonics 1(2), 115–118 (2007).
    [CrossRef]
  6. J. T. Robinson, L. Chen, and M. Lipson, “On-chip gas detection in silicon optical microcavities,” Opt. Express 16(6), 4296–4301 (2008).
    [CrossRef] [PubMed]
  7. C. A. Barrios, K. B. Gylfason, B. Sánchez, A. Griol, H. Sohlström, M. Holgado, and R. Casquel, “Slot-waveguide biochemical sensor,” Opt. Lett. 32(21), 3080–3082 (2007).
    [CrossRef] [PubMed]
  8. C. A. Barrios, M. J. Bañuls, V. González-Pedro, K. B. Gylfason, B. Sánchez, A. Griol, A. Maquieira, H. Sohlström, M. Holgado, and R. Casquel, “Label-free optical biosensing with slot-waveguides,” Opt. Lett. 33(7), 708–710 (2008).
    [CrossRef] [PubMed]
  9. T. Claes, J. G. Molera, K. De Vos, E. Schacht, R. Baets, and P. Bienstman, “Label-Free Biosensing With a Slot-Waveguide-Based Ring Resonator in Silicon on Insulator,” IEEE Photonics J. 1(3), 197–204 (2009).
    [CrossRef]
  10. S. Lee, S. C. Eom, J. S. Chang, C. Huh, G. Y. Sung, and J. H. Shin, “A silicon nitride microdisk resonator with a40-nm-thin horizontal air slot,” Opt. Express 18(11), 11209–11215 (2010).
    [CrossRef] [PubMed]
  11. L. Xianghuai, Y. Yuehui, Z. Zhihong, H. Wei, Z. Shichang, J. Zuqing, C. Ming, X. Shoulian, S. Taniguchi, T. Shibata, and K. Nakamura, “Properties and structure of silicon nitride films synthesized by ion-beam-enhanced deposition,” Surf. Coat. Tech. 46(2), 227–232 (1991).
    [CrossRef]
  12. J. T. Robinson, K. Preston, O. Painter, and M. Lipson, “First-principle derivation of gain in high-index-contrast waveguides,” Opt. Express 16(21), 16659–16669 (2008).
    [CrossRef] [PubMed]
  13. I. M. White and X. Fan, “On the performance quantification of resonant refractive index sensors,” Opt. Express 16(2), 1020–1028 (2008).
    [CrossRef] [PubMed]
  14. K. M. De Vos, I. Bartolozzi, P. Bienstman, R. Baets, and E. Schacht, “Optical biosensor based on silicon-on-insulator microring cavities for specific protein binding detection,” in Nanoscale Imaging, Spectroscopy, Sensing, and Actuation for Biomedical Applications IV(SPIE, San Jose, CA, USA, 2007), pp. 64470K–64478.
  15. N. Daldosso, M. Melchiorri, F. Riboli, M. Girardini, G. Pucker, M. Crivellari, P. Bellutti, A. Lui, and L. Pavesi, “Comparison Among Various Si3N4 Waveguide Geometries Grown Within a CMOS Fabrication Pilot Line,” J. Lightwave Technol. 22(7), 1734–1740 (2004).
    [CrossRef]
  16. J. S. Chang, S. C. Eom, G. Y. Sung, and J. H. Shin, “On-chip, planar integration of Er doped silicon-rich silicon nitride microdisk with SU-8 waveguide with sub-micron gap control,” Opt. Express 17(25), 22918–22924 (2009).
    [CrossRef]
  17. I. Fränz and W. Langheinrich, “Conversion of silicon nitride into silicon dioxide through the influence of oxygen,” Solid-State Electron. 14(6), 499–505 (1971).
    [CrossRef]
  18. A. V. Pesse, G. R. Warrier, and V. K. Dhir, “An experimental study of the gas entrapment process in closed-end microchannels,” Int. J. Heat Mass Transfer 48(25-26), 5150–5165 (2005).
    [CrossRef]
  19. D. Hohlfeld and H. Zappe, “An all-dielectric tunable optical filter based on the thermo-optic effect,” J. Opt. A, Pure Appl. Opt. 6(6), 504–511 (2004).
    [CrossRef]

2010 (1)

2009 (3)

2008 (5)

2007 (3)

2005 (1)

A. V. Pesse, G. R. Warrier, and V. K. Dhir, “An experimental study of the gas entrapment process in closed-end microchannels,” Int. J. Heat Mass Transfer 48(25-26), 5150–5165 (2005).
[CrossRef]

2004 (3)

1991 (1)

L. Xianghuai, Y. Yuehui, Z. Zhihong, H. Wei, Z. Shichang, J. Zuqing, C. Ming, X. Shoulian, S. Taniguchi, T. Shibata, and K. Nakamura, “Properties and structure of silicon nitride films synthesized by ion-beam-enhanced deposition,” Surf. Coat. Tech. 46(2), 227–232 (1991).
[CrossRef]

1971 (1)

I. Fränz and W. Langheinrich, “Conversion of silicon nitride into silicon dioxide through the influence of oxygen,” Solid-State Electron. 14(6), 499–505 (1971).
[CrossRef]

Almeida, V. R.

Baets, R.

T. Claes, J. G. Molera, K. De Vos, E. Schacht, R. Baets, and P. Bienstman, “Label-Free Biosensing With a Slot-Waveguide-Based Ring Resonator in Silicon on Insulator,” IEEE Photonics J. 1(3), 197–204 (2009).
[CrossRef]

K. De Vos, I. Bartolozzi, E. Schacht, P. Bienstman, and R. Baets, “Silicon-on-Insulator microring resonator for sensitive and label-free biosensing,” Opt. Express 15(12), 7610–7615 (2007).
[CrossRef] [PubMed]

Bañuls, M. J.

Barrios, C. A.

Bartolozzi, I.

Bellutti, P.

Benabid, F.

G. S. Wiederhecker, C. M. B. Cordeiro, F. Couny, F. Benabid, S. A. Maier, J. C. Knight, C. H. B. Cruz, and H. L. Fragnito, “Field enhancement within an optical fibre with a subwavelength air core,” Nat. Photonics 1(2), 115–118 (2007).
[CrossRef]

Bienstman, P.

T. Claes, J. G. Molera, K. De Vos, E. Schacht, R. Baets, and P. Bienstman, “Label-Free Biosensing With a Slot-Waveguide-Based Ring Resonator in Silicon on Insulator,” IEEE Photonics J. 1(3), 197–204 (2009).
[CrossRef]

K. De Vos, I. Bartolozzi, E. Schacht, P. Bienstman, and R. Baets, “Silicon-on-Insulator microring resonator for sensitive and label-free biosensing,” Opt. Express 15(12), 7610–7615 (2007).
[CrossRef] [PubMed]

Casquel, R.

Chang, J. S.

Cheben, P.

Chen, L.

Claes, T.

T. Claes, J. G. Molera, K. De Vos, E. Schacht, R. Baets, and P. Bienstman, “Label-Free Biosensing With a Slot-Waveguide-Based Ring Resonator in Silicon on Insulator,” IEEE Photonics J. 1(3), 197–204 (2009).
[CrossRef]

Cordeiro, C. M. B.

G. S. Wiederhecker, C. M. B. Cordeiro, F. Couny, F. Benabid, S. A. Maier, J. C. Knight, C. H. B. Cruz, and H. L. Fragnito, “Field enhancement within an optical fibre with a subwavelength air core,” Nat. Photonics 1(2), 115–118 (2007).
[CrossRef]

Couny, F.

G. S. Wiederhecker, C. M. B. Cordeiro, F. Couny, F. Benabid, S. A. Maier, J. C. Knight, C. H. B. Cruz, and H. L. Fragnito, “Field enhancement within an optical fibre with a subwavelength air core,” Nat. Photonics 1(2), 115–118 (2007).
[CrossRef]

Crivellari, M.

Cruz, C. H. B.

G. S. Wiederhecker, C. M. B. Cordeiro, F. Couny, F. Benabid, S. A. Maier, J. C. Knight, C. H. B. Cruz, and H. L. Fragnito, “Field enhancement within an optical fibre with a subwavelength air core,” Nat. Photonics 1(2), 115–118 (2007).
[CrossRef]

Daldosso, N.

De Vos, K.

T. Claes, J. G. Molera, K. De Vos, E. Schacht, R. Baets, and P. Bienstman, “Label-Free Biosensing With a Slot-Waveguide-Based Ring Resonator in Silicon on Insulator,” IEEE Photonics J. 1(3), 197–204 (2009).
[CrossRef]

K. De Vos, I. Bartolozzi, E. Schacht, P. Bienstman, and R. Baets, “Silicon-on-Insulator microring resonator for sensitive and label-free biosensing,” Opt. Express 15(12), 7610–7615 (2007).
[CrossRef] [PubMed]

Delâge, A.

Densmore, A.

Dhir, V. K.

A. V. Pesse, G. R. Warrier, and V. K. Dhir, “An experimental study of the gas entrapment process in closed-end microchannels,” Int. J. Heat Mass Transfer 48(25-26), 5150–5165 (2005).
[CrossRef]

Eom, S. C.

Fan, X.

I. M. White and X. Fan, “On the performance quantification of resonant refractive index sensors,” Opt. Express 16(2), 1020–1028 (2008).
[CrossRef] [PubMed]

X. Fan, I. M. White, S. I. Shopova, H. Zhu, J. D. Suter, and Y. Sun, “Sensitive optical biosensors for unlabeled targets: a review,” Anal. Chim. Acta 620(1-2), 8–26 (2008).
[CrossRef] [PubMed]

Fragnito, H. L.

G. S. Wiederhecker, C. M. B. Cordeiro, F. Couny, F. Benabid, S. A. Maier, J. C. Knight, C. H. B. Cruz, and H. L. Fragnito, “Field enhancement within an optical fibre with a subwavelength air core,” Nat. Photonics 1(2), 115–118 (2007).
[CrossRef]

Fränz, I.

I. Fränz and W. Langheinrich, “Conversion of silicon nitride into silicon dioxide through the influence of oxygen,” Solid-State Electron. 14(6), 499–505 (1971).
[CrossRef]

Girardini, M.

González-Pedro, V.

Griol, A.

Gylfason, K. B.

Hohlfeld, D.

D. Hohlfeld and H. Zappe, “An all-dielectric tunable optical filter based on the thermo-optic effect,” J. Opt. A, Pure Appl. Opt. 6(6), 504–511 (2004).
[CrossRef]

Holgado, M.

Huh, C.

Janz, S.

Knight, J. C.

G. S. Wiederhecker, C. M. B. Cordeiro, F. Couny, F. Benabid, S. A. Maier, J. C. Knight, C. H. B. Cruz, and H. L. Fragnito, “Field enhancement within an optical fibre with a subwavelength air core,” Nat. Photonics 1(2), 115–118 (2007).
[CrossRef]

Langheinrich, W.

I. Fränz and W. Langheinrich, “Conversion of silicon nitride into silicon dioxide through the influence of oxygen,” Solid-State Electron. 14(6), 499–505 (1971).
[CrossRef]

Lapointe, J.

Lee, S.

Li, Y. H.

Lipson, M.

Liu, Q. Y.

Lopinski, G.

Luebbert, C. C.

Lui, A.

Ma, R.

Maier, S. A.

G. S. Wiederhecker, C. M. B. Cordeiro, F. Couny, F. Benabid, S. A. Maier, J. C. Knight, C. H. B. Cruz, and H. L. Fragnito, “Field enhancement within an optical fibre with a subwavelength air core,” Nat. Photonics 1(2), 115–118 (2007).
[CrossRef]

Maquieira, A.

Melchiorri, M.

Ming, C.

L. Xianghuai, Y. Yuehui, Z. Zhihong, H. Wei, Z. Shichang, J. Zuqing, C. Ming, X. Shoulian, S. Taniguchi, T. Shibata, and K. Nakamura, “Properties and structure of silicon nitride films synthesized by ion-beam-enhanced deposition,” Surf. Coat. Tech. 46(2), 227–232 (1991).
[CrossRef]

Molera, J. G.

T. Claes, J. G. Molera, K. De Vos, E. Schacht, R. Baets, and P. Bienstman, “Label-Free Biosensing With a Slot-Waveguide-Based Ring Resonator in Silicon on Insulator,” IEEE Photonics J. 1(3), 197–204 (2009).
[CrossRef]

Nakamura, K.

L. Xianghuai, Y. Yuehui, Z. Zhihong, H. Wei, Z. Shichang, J. Zuqing, C. Ming, X. Shoulian, S. Taniguchi, T. Shibata, and K. Nakamura, “Properties and structure of silicon nitride films synthesized by ion-beam-enhanced deposition,” Surf. Coat. Tech. 46(2), 227–232 (1991).
[CrossRef]

Painter, O.

Pavesi, L.

Pesse, A. V.

A. V. Pesse, G. R. Warrier, and V. K. Dhir, “An experimental study of the gas entrapment process in closed-end microchannels,” Int. J. Heat Mass Transfer 48(25-26), 5150–5165 (2005).
[CrossRef]

Preston, K.

Pucker, G.

Riboli, F.

Robinson, J. T.

Sánchez, B.

Schacht, E.

T. Claes, J. G. Molera, K. De Vos, E. Schacht, R. Baets, and P. Bienstman, “Label-Free Biosensing With a Slot-Waveguide-Based Ring Resonator in Silicon on Insulator,” IEEE Photonics J. 1(3), 197–204 (2009).
[CrossRef]

K. De Vos, I. Bartolozzi, E. Schacht, P. Bienstman, and R. Baets, “Silicon-on-Insulator microring resonator for sensitive and label-free biosensing,” Opt. Express 15(12), 7610–7615 (2007).
[CrossRef] [PubMed]

Schmid, J. H.

Shibata, T.

L. Xianghuai, Y. Yuehui, Z. Zhihong, H. Wei, Z. Shichang, J. Zuqing, C. Ming, X. Shoulian, S. Taniguchi, T. Shibata, and K. Nakamura, “Properties and structure of silicon nitride films synthesized by ion-beam-enhanced deposition,” Surf. Coat. Tech. 46(2), 227–232 (1991).
[CrossRef]

Shichang, Z.

L. Xianghuai, Y. Yuehui, Z. Zhihong, H. Wei, Z. Shichang, J. Zuqing, C. Ming, X. Shoulian, S. Taniguchi, T. Shibata, and K. Nakamura, “Properties and structure of silicon nitride films synthesized by ion-beam-enhanced deposition,” Surf. Coat. Tech. 46(2), 227–232 (1991).
[CrossRef]

Shin, J. H.

Shopova, S. I.

X. Fan, I. M. White, S. I. Shopova, H. Zhu, J. D. Suter, and Y. Sun, “Sensitive optical biosensors for unlabeled targets: a review,” Anal. Chim. Acta 620(1-2), 8–26 (2008).
[CrossRef] [PubMed]

Shoulian, X.

L. Xianghuai, Y. Yuehui, Z. Zhihong, H. Wei, Z. Shichang, J. Zuqing, C. Ming, X. Shoulian, S. Taniguchi, T. Shibata, and K. Nakamura, “Properties and structure of silicon nitride films synthesized by ion-beam-enhanced deposition,” Surf. Coat. Tech. 46(2), 227–232 (1991).
[CrossRef]

Sohlström, H.

Sun, Y.

X. Fan, I. M. White, S. I. Shopova, H. Zhu, J. D. Suter, and Y. Sun, “Sensitive optical biosensors for unlabeled targets: a review,” Anal. Chim. Acta 620(1-2), 8–26 (2008).
[CrossRef] [PubMed]

Sung, G. Y.

Suter, J. D.

X. Fan, I. M. White, S. I. Shopova, H. Zhu, J. D. Suter, and Y. Sun, “Sensitive optical biosensors for unlabeled targets: a review,” Anal. Chim. Acta 620(1-2), 8–26 (2008).
[CrossRef] [PubMed]

Taniguchi, S.

L. Xianghuai, Y. Yuehui, Z. Zhihong, H. Wei, Z. Shichang, J. Zuqing, C. Ming, X. Shoulian, S. Taniguchi, T. Shibata, and K. Nakamura, “Properties and structure of silicon nitride films synthesized by ion-beam-enhanced deposition,” Surf. Coat. Tech. 46(2), 227–232 (1991).
[CrossRef]

Vachon, M.

Warrier, G. R.

A. V. Pesse, G. R. Warrier, and V. K. Dhir, “An experimental study of the gas entrapment process in closed-end microchannels,” Int. J. Heat Mass Transfer 48(25-26), 5150–5165 (2005).
[CrossRef]

Wei, H.

L. Xianghuai, Y. Yuehui, Z. Zhihong, H. Wei, Z. Shichang, J. Zuqing, C. Ming, X. Shoulian, S. Taniguchi, T. Shibata, and K. Nakamura, “Properties and structure of silicon nitride films synthesized by ion-beam-enhanced deposition,” Surf. Coat. Tech. 46(2), 227–232 (1991).
[CrossRef]

White, I. M.

X. Fan, I. M. White, S. I. Shopova, H. Zhu, J. D. Suter, and Y. Sun, “Sensitive optical biosensors for unlabeled targets: a review,” Anal. Chim. Acta 620(1-2), 8–26 (2008).
[CrossRef] [PubMed]

I. M. White and X. Fan, “On the performance quantification of resonant refractive index sensors,” Opt. Express 16(2), 1020–1028 (2008).
[CrossRef] [PubMed]

Wiederhecker, G. S.

G. S. Wiederhecker, C. M. B. Cordeiro, F. Couny, F. Benabid, S. A. Maier, J. C. Knight, C. H. B. Cruz, and H. L. Fragnito, “Field enhancement within an optical fibre with a subwavelength air core,” Nat. Photonics 1(2), 115–118 (2007).
[CrossRef]

Xianghuai, L.

L. Xianghuai, Y. Yuehui, Z. Zhihong, H. Wei, Z. Shichang, J. Zuqing, C. Ming, X. Shoulian, S. Taniguchi, T. Shibata, and K. Nakamura, “Properties and structure of silicon nitride films synthesized by ion-beam-enhanced deposition,” Surf. Coat. Tech. 46(2), 227–232 (1991).
[CrossRef]

Xu, D. X.

Xu, Q.

Yuehui, Y.

L. Xianghuai, Y. Yuehui, Z. Zhihong, H. Wei, Z. Shichang, J. Zuqing, C. Ming, X. Shoulian, S. Taniguchi, T. Shibata, and K. Nakamura, “Properties and structure of silicon nitride films synthesized by ion-beam-enhanced deposition,” Surf. Coat. Tech. 46(2), 227–232 (1991).
[CrossRef]

Zappe, H.

D. Hohlfeld and H. Zappe, “An all-dielectric tunable optical filter based on the thermo-optic effect,” J. Opt. A, Pure Appl. Opt. 6(6), 504–511 (2004).
[CrossRef]

Zhihong, Z.

L. Xianghuai, Y. Yuehui, Z. Zhihong, H. Wei, Z. Shichang, J. Zuqing, C. Ming, X. Shoulian, S. Taniguchi, T. Shibata, and K. Nakamura, “Properties and structure of silicon nitride films synthesized by ion-beam-enhanced deposition,” Surf. Coat. Tech. 46(2), 227–232 (1991).
[CrossRef]

Zhu, H.

X. Fan, I. M. White, S. I. Shopova, H. Zhu, J. D. Suter, and Y. Sun, “Sensitive optical biosensors for unlabeled targets: a review,” Anal. Chim. Acta 620(1-2), 8–26 (2008).
[CrossRef] [PubMed]

Zuqing, J.

L. Xianghuai, Y. Yuehui, Z. Zhihong, H. Wei, Z. Shichang, J. Zuqing, C. Ming, X. Shoulian, S. Taniguchi, T. Shibata, and K. Nakamura, “Properties and structure of silicon nitride films synthesized by ion-beam-enhanced deposition,” Surf. Coat. Tech. 46(2), 227–232 (1991).
[CrossRef]

Anal. Chim. Acta (1)

X. Fan, I. M. White, S. I. Shopova, H. Zhu, J. D. Suter, and Y. Sun, “Sensitive optical biosensors for unlabeled targets: a review,” Anal. Chim. Acta 620(1-2), 8–26 (2008).
[CrossRef] [PubMed]

IEEE Photo. J. (1)

T. Claes, J. G. Molera, K. De Vos, E. Schacht, R. Baets, and P. Bienstman, “Label-Free Biosensing With a Slot-Waveguide-Based Ring Resonator in Silicon on Insulator,” IEEE Photonics J. 1(3), 197–204 (2009).
[CrossRef]

Int. J. Heat Mass Transfer (1)

A. V. Pesse, G. R. Warrier, and V. K. Dhir, “An experimental study of the gas entrapment process in closed-end microchannels,” Int. J. Heat Mass Transfer 48(25-26), 5150–5165 (2005).
[CrossRef]

J. Lightwave Technol. (1)

J. Opt. A, Pure Appl. Opt. (1)

D. Hohlfeld and H. Zappe, “An all-dielectric tunable optical filter based on the thermo-optic effect,” J. Opt. A, Pure Appl. Opt. 6(6), 504–511 (2004).
[CrossRef]

Nat. Photonics (1)

G. S. Wiederhecker, C. M. B. Cordeiro, F. Couny, F. Benabid, S. A. Maier, J. C. Knight, C. H. B. Cruz, and H. L. Fragnito, “Field enhancement within an optical fibre with a subwavelength air core,” Nat. Photonics 1(2), 115–118 (2007).
[CrossRef]

Opt. Express (6)

Opt. Lett. (4)

Solid-State Electron. (1)

I. Fränz and W. Langheinrich, “Conversion of silicon nitride into silicon dioxide through the influence of oxygen,” Solid-State Electron. 14(6), 499–505 (1971).
[CrossRef]

Surf. Coat. Tech. (1)

L. Xianghuai, Y. Yuehui, Z. Zhihong, H. Wei, Z. Shichang, J. Zuqing, C. Ming, X. Shoulian, S. Taniguchi, T. Shibata, and K. Nakamura, “Properties and structure of silicon nitride films synthesized by ion-beam-enhanced deposition,” Surf. Coat. Tech. 46(2), 227–232 (1991).
[CrossRef]

Other (1)

K. M. De Vos, I. Bartolozzi, P. Bienstman, R. Baets, and E. Schacht, “Optical biosensor based on silicon-on-insulator microring cavities for specific protein binding detection,” in Nanoscale Imaging, Spectroscopy, Sensing, and Actuation for Biomedical Applications IV(SPIE, San Jose, CA, USA, 2007), pp. 64470K–64478.

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Figures (4)

Fig. 1
Fig. 1

(a) SEM image of the deposited multilayer thin film prior to disk formation, (b) DIC optical microscope image of the fabricated microdisk after air slot fabrication. The green inner boundary indicates the silicon post and the whiter outer region indicates air slot with depth of more than 2μm. (c)(d) SEM images of fabricated slot disk after whole sensing process. Note that the air-slot is maintained despite repeated washing/drying measurement steps.

Fig. 2
Fig. 2

(a) Simulated mode profile of |E|2 with bare fabricated structure (b) schematic of surface sensing (c) Calculated shift in the resonance wavelength versus thickness of adsorbed layer with a refractive index of 1.45. The surface sensitivity is obtained as 5.73nm/nm with linear fit.

Fig. 3
Fig. 3

(a) Schematic of the measurement system. (b) CCD image of a slot disk coupled with a tapered fiber. The fiber diameter is ~1μm.

Fig. 4
Fig. 4

(a) Transmission spectra before and after reacting streptavidin with concentration of 20μg/ml (b) Dependence of the resonance peak shift of the fundamental radial mode on the streptavidin concentration. The initial linear slope gives the sensitivity, measured to be 2.48 nm/(μg/ml). (c) High resolution scan of the resonance dip before and after binding of streptavidin. The same Q-factor of ~7,000 is obtained in both cases.

Equations (2)

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Γ = n A c ε 0 A | E | 2 d x d y Re { E × H } e z ^ d x d y n g n A γ A ,  where  γ A = A ε | E | 2 d x d y ε | E | 2 d x d y .
S s u r f a c e = λ r e s / t b i o [ n m / n m ] ,

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