Surface plasmon resonance sensor
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Surface plasmon resonance (SPR) sensors are optical sensors that can detect minute changes in the refractive index near a metal surface. They have various applications in biomedical sensing, environmental monitoring, and more. SPR sensors can be classified as surface plasmon polariton-based or localized surface plasmon resonance-based. Sensitivity, detection limit, and dynamic range are important characteristics. SPR sensing can be performed through angular modulation, wavelength modulation, intensity modulation, or phase/polarization modulation. Diffraction gratings and prism couplers are common methods used to excite surface plasmons. Localized SPR sensors offer advantages like simpler instrumentation but lower sensitivity compared to SPR sensors.
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Surface plasmon resonance sensor
- 1. Surface plasmon resonance sensors –A future sensing technology Presented by R.Gandhimathi
- 2. Sensors -convert one form energy into electrical energy Optical sensors-convert light energy into electrical energy Surface plasmon resonance (SPR) sensor - an optical sensor fabricated based on photonic excitation Introduction to surface plasmon resonance sensor Classification ▪ Surface Plasmon Polariton (SPP) based sensor ▪ Localized surface plasmon resonance (LSPR) based sensors Plasmonic sensors are fabricated using ▪ nanoparticles ▪ nanopatterned gratings ▪ Prism couplers ▪ Metal/Dielectric waveguide Characteristics of sensors ▪ Sensitivity ▪ Detection limit ▪ Dynamic range performance SPR sensor applications ▪ Biomedical ▪ Food science ▪ Environmental monitoring ▪ Toxic or chemical compound detection ▪ Pharmacy and industry ▪ Medical diagnostics SPR sensor is vey sensitive to variation in the refractive index of the medium located next to the metallic film
- 3. ▪ The incident light is directly coupled with SPs (tightly confined optical field) ▪ Change in the refractive index of the analyte produces a variation in the propagation constant of the surface plasmon ▪ It means a modification in one of the characteristics of the optical wave interacting with the surface plasmon ▪ Binding between the analyte and the recognition molecule caused changes in the refractive index of the dielectric and is monitored as a shift in the resonance wavelength of the light A strong EM field oscillation at the interface of metal/dielectric media with p-polarized incident light resulting in a dark band profile in the light reflectivity at a specific wavelength(res) and incident angle(I). SPR Sensor Configuration Surface plasmon Polariton SPR condition is sensitive to the environment variations and that can be utilized as sensors Principle Prism coupler-based SPR sensor Prism coupler employing the attenuated total reflection method in Kretschmann geometry is the widely used method in SPR biosensors applications
- 4. At Resonance z SPPk k= 2 0 0 2 sin mr a p mr a n k n k n = + The expression for the sensitivity is obtained by differentiating resonant condition equation with respect to , , I, and na SPR sensor with ▪ Angular Modulation ▪ Wave length Modulation ▪ Intensity Modulation ▪ Phase or polarization modulation 0 sinz pk k n =Incident light m mr = 2 d an =where 2 0 0 2 sin mr a z p mr a n k k n k n = = + 𝑘0 − 𝐹𝑟𝑒𝑒 𝑠𝑝𝑎𝑐𝑒 𝑤𝑎𝑣𝑒 𝑛𝑢𝑚𝑏𝑒𝑟 𝜀 𝑚𝑟 − 𝑅𝑒𝑎𝑙 𝑝𝑎𝑟𝑡 𝑜𝑓 𝑑𝑖𝑒𝑙𝑒𝑐𝑡𝑟𝑖𝑐 𝑐𝑜𝑛𝑠𝑡𝑎𝑛𝑡 𝑜𝑓 𝑚𝑒𝑡𝑎𝑙𝑠 𝑛 𝑝 − 𝑟𝑒𝑓𝑟𝑎𝑐𝑡𝑖𝑣𝑒 index of prism 𝑛 𝑎 − 𝑅𝑒𝑓𝑟𝑎𝑐𝑡𝑖𝑣𝑒 𝑖𝑛𝑑𝑒𝑥 𝑜𝑓 𝑎𝑛𝑎𝑙𝑦𝑡𝑒 Propagation constant The excitation of surface plasmons in the SPR sensor results in a change in one of the characteristics of the light wave. Based on which characteristics of the light wave is interacting with surface plasmon is measured and used as a sensor output. P a S n =I a I S n =𝑆 𝜃 = 𝛿𝜃 𝛿𝑛 𝑎 𝑆𝜆 = 𝛿𝜆 𝑟𝑒𝑠 𝛿𝑛 𝑎 2 m d SPP m d k = + SPP 2 2 sin mr a p mr a n n n = + Resonance condition Classification Angular, Wavelength, Intensity and phase sensitivity
- 5. ▪ A monochromatic light wave is employed to excite the surface plasmon ▪ The excited surface plasmon is observed at multiple angles of incident light ▪ The strength of coupling between the incident wave and the surface plasmon depends upon the angles of incident light ▪ Angle of incidence yielding the strongest coupling is measured and used as a sensor output ▪ The sensor output is calibrated to refractive index deg a S n RIU = = Angular sensitivity 2 deg 10S RIU = - represents the change of resonance angle -change in the refractive index 𝛿𝜃 𝛿𝑛 𝑎 At constant wavelength The angle yielding the minimum light intensity on the SPR curve is denoted as the resonance angle Addition of diffractive grating and temperature and noise stabilization are the ways to increase angular sensitivity 2 2 2 2 2 ( ) ( ) mr mr a mr a mr a p a p S n n n n n n − = = + − − Angular modulation
- 6. ▪ Surface plasmon is excited by a collimated light wave containing multiple wavelengths. ▪ Angle at which the light wave is incident onto the metal film is kept constant. ▪ Coupling strength between the incident wave and SP is observed at multiple wavelengths and the wavelength yielding the strongest coupling is measured and used as a sensor output ▪ Resonance wavelength is known to shift to the longer wavelength (red shift) as the refractive index at the sensor/dielectric medium is increased ▪ wavelength Modulation based SPR sensors using prism couplers provide much better sensitivity than their grating-based counterparts ▪ Usage of Furie spectrometers, and multi-channel sensing help to improve sensitivity 3 4 10 10 nm S RIU = − The wavelength sensitivity of the SPR sensor is defined as the ratio between the resonance wavelength shift to the variation of the refractive index of the surrounding medium Wavelength modulation where Sλ is the SPR sensor sensitivity is the shift in the SPR resonance wavelength is the change in the refractive index 𝛿𝜆 𝑟𝑒𝑠 𝛿𝑛 𝑎 Wavelength sensitivity 2 3 2 ( ) 2 res mr pa mr aa mr a mr p S nn d nn n n = = + +
- 7. 𝛿𝑛 𝑎 = 𝑛2 − 𝑛1 ▪ Excitation by single incidence angle and wavelength by changing the intensity of light ▪ P-polarized wave incident light is used and they are very sensitive to any intensity fluctuations of the light source ▪ Light source must be of high quality and stability ▪ Intensity is spatially modulated due to the excitation of surface plasmons and the changes are simultaneously measured in sensing channel by means of a spatially sensitive detector such as two-dimensional charge coupled device ▪ Sensor output is defined as the difference of these two reflected intensities which is proportional to the reflectance 3 4 1 % 10 10S RIU = − I a I S n = Intensity modulation The detection of small refractive index changes over a relatively large volume is successful on sensors based on an intensity modulation scheme down to a sensitivity of 10-6 RIU Two light sources with different wavelength help to improve the sensitivity with intensity modulation Typical sensitivity- 15000% 𝑅𝐼𝑈
- 8. ▪ Surface plasmon excitation by shift in phase of the light wave at a incidence angle and wavelength ▪ Explicitly used for the coherent monochromatic light source in SPR instrumentation ▪ It needs phase shift equipment such as a lock in amplifier where ∆ϕ is the differential phase changes corresponding to ∆n The phase sensitivity which is defined as 𝛿𝑛 𝑎 = 𝑛2 − 𝑛1 Phase or polarization Modulation P a S n = Other than sensitivity the figure of merit (FOM) is another important parameter to characterize sensor performance FWHM contains information on light absorption by the binding molecules 𝐹𝑂𝑀 = 𝑆 𝐹𝑊𝐻𝑀 Where S denotes Sensitivity
- 9. LSPR sensor SPR sensor Resonance conditions are simpler The energy and momentum matching conditions should be satisfied Small size of plasma field (20-40nm) Marginal bulk effect Larger plasma field (200-1000nm) Large Bulk effect complexity resides in the surface of the chip complexity resides in the instrumentation set up to excite SPR and read it accurately. Temperature independent More sensitive to thermal variation Instrumentally simple Instrumentally complex Localized surface plasmon resonance (LSPR) sensors ▪ A label-free and powerful surface sensing platform with higher sensitivity, simple fabrication and measurement equipment ▪ The extreme chemical sensitivity of metal nanoparticles to minute changes in the local dielectric environment, is revealed as a discrete change to their optical response due to surface adsorption ▪ In LSPR sensor, light passes through the sample solution are affected by absorption or scattering of the sample ▪ Requires a simple optical configuration without a prism ▪ Cost-effective and suitable for miniaturization
- 10. Analyte Metal grating Reflected light P-polarized Incident light Grating period SPR sensors using diffraction gratings Incident light 2 sinz ak n = Diffracted wave vector 2 2 sinzm ak n m = + At resonance SPP zmk k= 2 2 2 sin m d a m d n m + = + After Simplification sin m d a m d n m + = + At resonance condition 2 2 sin mr a a mr a n n m n + = + 2 22 3 3 2 22 a mr mr amr a a mra mr mr a nm na nn nmn n + ++ = + + 3 2 2 1 sin( ) cos( ) mr a a mr an n n = − + Angular Modulation Wave length Modulation ▪ The momentum mismatch is compensated by diffraction using a metallic diffraction grating ▪ The resonant transfer of optical energy into an SPP is observed as a dip in the angular or wavelength spectrum of reflected light ▪ Light propagates into the core through total internal reflection and generates an evanescent field in the vicinity of the waveguide boundary, which induces SPR at the interface between the metal film and the sensing medium ▪ Provides highly integrated, multichannel, and robust sensing devices The expression for the sensitivity is obtained by differentiating resonant condition with respect to , and na -grating period Wave guide-based sensor ▪ Planar waveguide configuration - unable to interrogate the incident angle scanning ▪ Wavelength interrogation is the only option for the signal acquisition technique
- 11. 1. B. Liedberg, C. Nylander, I. Lunstrom, “Surface Plasmon resonance for gas detection and biosensing”, Sens. Actuat. 4.p.299(1983). 2. Briliant Adhi Prabowo, Agnes Purwidyantri and Kou-Chen Liu, Surface Plasmon Resonance Optical Sensor: A Review on Light Source Technology, Biosensors 2018, 8, 80 3. Shaoqing cao, Yu shao, Ying wang, Tiesheng wu, Longfei zhang, Yijian huang, Feng zhang, Changrui liao, Jun he, and Yiping wang, highly sensitive surface plasmon resonance biosensor based on a low-index polymer optical fiber Vol. 26, No. 4 2018 OPTICS EXPRESS 3988, 4. Qian, Yifeng; Zeng, Xie; Gao, Yongkang; Li, Hang; Kumar, Sushil; Gan, Qiaoqiang; Cheng, Xuanhong; Bartoli, Filbert J., Intensity-modulated nanoplasmonic interferometric sensor for MMP-9 detection, Lab Chip ; 19(7): 1267-1276, 2019 03 27. 5. Ahmmed A.RifataRajibAhmedbAli K.YetisencdHaiderButtbAydinSabouribG. AmouzadMahdirajieSeok HyunYuncdF.R. MahamdAdikana, Photonic crystal fiber based plasmonic sensors, Sensors and Actuators B: Chemical, Volume 243, May 2017, 311-325 6. Xiang Zhao 1 , Tianye Huang 1,* ID , Perry Shum Ping 2 , Xu Wu 1 , Pan Huang 1 , Jianxing Pan 1 , Yiheng Wu 1 and Zhuo Cheng 1 Sensitivity Enhancement in Surface Plasmon Resonance Biochemical Sensor Based on Transition Metal Dichalcogenides/Graphene Heterostructure, Sensors 2018, 18, 2056; doi:10.3390/s18072056 7. DONGPING WANG, 1 FONG-CHUEN LOO, 2,3 HENGJI CONG, 2 WEI LIN, 1 SIU KAI KONG, 3 YEUNG YAM, 1 SHIH-CHI CHEN, 1,* AND HO PUI HO2, Real-time multi-channel SPR sensing based on DMD-enabled angular interrogation Vol. 26, No. 19 | 17 Sep 2018 | OPTICS EXPRESS 24627 8. Jir'ı´ Homola, Ivo Koudela, Sinclair S. Yee, “Surface plasmon resonance sensors based on diffraction gratings and prism couplers: sensitivity comparison”, Sensors and Actuators B 54 (1999) 16–24 9. Jianjun Cao, Yuan Sun, Yan Kong and Weiying Qian, “The Sensitivity of Grating-Based SPR Sensors with Wavelength Interrogation” Sensors 2019, 19, 405; 10.F. Wu, P. A. Thomas, V. G. Kravets, H. O. Arola, M. Soikkeli, K. Iljin, G. Kim, M. Kim,H. S. Shin D. V. Andreeva, C. Neumann, M. Küllmer, A. Turchanin, D. De Fazio ,O. Balci , V. Babenko, B. Luo, I. Goykhman, S. Hofmann, A. C. Ferrari K. S. Novoselov & A. N. Grigorenko” Layered material latform for surface plasmon resonance biosensing”Scientific Reports | (2019) 9:20286 11.G. Ruffato, G. Zacco and F. Romanato, Innovative Exploitation of Grating-Coupled Surface Plasmon Resonance for Sensing, http://dx.doi.org/10.5772/51044 12.Radan Slavik, Jiri Homola, Jiri Ctyroky, Eduard Brynda, Novel Spectral Fiber Optic Sensor based on Surface Plasmon Resonance, Sensors and Actuators B, 74, 106-111 References
- 12. Thank you