Biometric Sensing: Plasmonic Theory and Label-free Applications University of Minnesota-Duluth EE4611: Semiconductor Physics and Devices Joshua MacVey Dr. S. Burns

Outline Biosensors: Introduction & Plasmonic Motivation Some Needed Background: What is a plasmon? Optical Biosensors Label-Free Biosensor: Surface Plasmon Biosensors – Surface plasmon resonance biosensors: Qualitative – Surface plasmon resonance biosensors: Quantitative

Outline Biosensors: Introduction & Plasmonic Motivation Some Needed Background: What is a plasmon? Optical Biosensors Label-Free Biosensor: Surface Plasmon Biosensors – Surface plasmon resonance biosensors: Qualitative – Surface plasmon resonance biosensors: Quantitative

The Why & What of biosensors measure biomolecules: Proteins DNA Etc. applications in: Diagnostics Drug research And, of course… $$

Strong Growth Predicted for Biosensors Market

Broad Categories: Labeled vs label-free Extreme Generality

What is labeling? Attachment of a fluorescent marker to biomolecule + = measure signal under laser excitation CAN WE THINK OF ANY PROS AND CONS TO LABELING? signal laser

Label-free sensing 1.55 μm Example: Ring-resonator ΔP Δλ  Δλ 1.55 μm Sun, et. al (2010)

Plasmonic Nanophotonics: a logical next step?

Why plasmonics?

Outline Biosensors: Introduction & Plasmonic Motivation Some Needed Background: What is a plasmon? Optical Biosensors Label-Free Biosensor: Surface Plasmon Biosensors – Surface plasmon resonance biosensors: Qualitative & Theoretical – Surface plasmon resonance biosensors: Quantitative

What is a plasmon? A plasmon is a density wave in an electron gas - a collective oscillations of the free electron gas density. It is analogous to a sound wave, which is a density wave in a real gas of molecules. Prof. Polman’s nanophotonic course@Amolf

What is a plasmon? + + + Bulk plasmon - - - k + - + Surface plasmon + + + Ne2 Bulk plasmon Plasmons in the bulk oscillate at  p  drude m0 determined by the free electron density and effective mass - - - k + - + Plasmons confined to surfaces that can interact with light to form propagating “surface plasmon polaritons (SPP)” Metal Surface plasmon Confinement effects result in resonant SPP modes in nanoparticles Localized Surface plasmon Prof. Polman’s nanophotonic course@Amolf

Surface plasmon (or surface plasmon-polariton ) H dielectric k E + - + Note: this is a TM wave

Localized Surface plasmon

Wavelength dependent local field intensity

Plasmon propagation in micro-/nano- wires R. M. Dickson et al. J. Phys. Chem. B 104, 6095 (2000) B. Wild et al. ACS Nano 6, 472 (2011)

Applications of surface plasmons: An example device Surface plasmon resonance biosensors But before we get to this…

Outline Biosensors: Introduction & Plasmonic Motivation Some Needed Background: What is a plasmon? Optical Biosensors Label-Free Biosensor: Surface Plasmon Biosensors – Surface plasmon resonance biosensors: Qualitative – Surface plasmon resonance biosensors: Quantitative

Approaches to enhance biosensing performance 1. Enhancing sensitivity Δλ Δλ Intensity Intensity Wavelength low sensitivity Wavelength high sensitivity

Approaches to enhance biosensing performance 2. Enhancing selectivity high Q-factor (high selectivity) P λ Δλ Intensity P FWHM λ Sensitivity Increases with increasing Q factor of the ring Q  resonance/ Δλ Wavelength 3dB low Q-factor (low selectivity)

Outline Biosensors: Introduction & Plasmonic Motivation Some Needed Background: What is a plasmon? Optical Biosensors Label-Free Biosensor: Surface Plasmon Biosensors – Surface plasmon resonance biosensors: Qualitative – Surface plasmon resonance biosensors: Quantitative

Theory: Surface Plasmons Evanescent TM polarized electromagnetic waves bound to the surface of a metal Benefits for Biosensing High fields near the interface are very sensitive to refractive index changes Gold is very suitable for biochemistry Prism Gold From source To detector R  Dr. Peter Debackere’s Internal tutorial

Configurations: How can we excite SPP Modes? Kretschman Resonant Mirror Otto Configuration Configuration Configuration Fiber optics Sensors Waveguide Integrated SPR LSPR nanosensor

Outline Biosensors: Introduction & Plasmonic Motivation Some Needed Background: What is a plasmon? Optical Biosensors Label-Free Biosensor: Surface Plasmon Biosensors – Surface plasmon resonance biosensors: Qualitative – Surface plasmon resonance biosensors: Quantitative

Applications of surface plasmons: An example device Surface plasmon resonance biosensors And we’re back.

Kretschmann : Design Thickness of the Metal ? Which metal ?

Response Curves Angular Response Spectral Response Au thickness 44 nm, resonance angle 65.58 degrees, resonant wavelength 650 nm

Response Curves Angular Response Spectral Response 657 nm 677 nm 65.61˚ 65.71˚ Au thickness 44 nm, resonance angle 65.58 degrees, resonant wavelength 650 nm

Response Curves Angular Response Spectral Response 1610 nm 1683 nm 22.73˚ 22.75˚ Au-layer thickness 38 nm resonance angle 22.71 degrees resonance wavelength 1600

Sensitivity BK 7 Glass Prism Silicon Prism Sensitivity [nm/RIU] Wavelength shift [nm/RIU] [nm/RIU] spectral half width 300 250 200 150 100 50 0.6 0.8 1 Wavelength shift Sensitivity total contribution FRESN 10000 0.6 0.65 0.7 0.75 0.8 0.85 0.9 0.95 Wavelength [um] Sensitivity [nm/RIU] 40000 90000 spectral half width 440 420 400 380 360 340 35000 85000 80000 30000 1.53 1.58 1.63 1.68 75000 25000 70000 20000 65000 15000 Sensitivity total contribution 60000 1.5 1.55 1.6 Wavelength [um] 1.65

LSPR biosensor consists of 3 major components Localized surface plasmon resonance (LSPR) biosensor LSPR sensing streptavidin binding to biotin LSPR biosensor consists of 3 major components Plasmonic surface: signal transduction Passivating layer: reduces nonspecific binding Probe layer: recognize specific targets

Surface plasmon resonance (SPR) biosensor SPR sensing streptavidin binding to biotin Ag Δλ=12.7nm Single nanoparticle SPR biosensor

Summary and Conclusions - Electronics and Photonics alone are insufficient technologies given the need for enhanced speed and precision of biosensing devices. - SPR technology is label-free and precise. - SPR (Surface Plasmon Resonance) biosensing can be designed using a variety of geometric and chemical specifications reflective of chemical compositions. - SPR technology may be further optimized for sensitivity and selectivity for specified wavelengths. - SPR technology can further optimize spatial organization on chips.

References & Acknowledgements B. Wild et al. ACS Nano 6, 472 (2011). Bogaerts, W., Baets, R., & Bienstein, P. (2005, January). Nanophotonic waveguides in silicon-on-insulator fabricated with CMOS technology. Journal of Lightwave Technology, 23(1), 401-412. How does surface plasmon resonance work?. (2015). In Bionavis. Retrieved April 15, 2015, from http://www.bionavis.com/technology/spr/ Gaponenko, S. V. (2010). Introduction to nanophotonics (pp. 297-311). Cambridge: Cambridge University. Khai Q. Le and P. Bienstman, Nanoplasmonic resonator for biosensing applications, 15th Annual Symposium of the IEEE Photonics Benelux Chapter, Deft, Netherlands (2010). Khai Q. Le, B. Maes and P. Bienstman, Numerical study of plasmonic nanoparticles enhanced light emission in silicon light-emitting-diodes, 15th European Conference on Integrated Optics, United Kingdom (2010). Sensor technology alert. distributed fiber sensor; surface plasmon resonance; wearable glucose sensor. (2006, December 1). In Frost & Sullivan. Sun, Y., & Fan, X. (2010, June 6). Optical ring resonators for biochemical and chemical sensing. Anal. Bioanal Chemistry, 205-211. doi:10.1007/s00216-010-4237-z Powell, C. J., & Swan, J. B. (1959, March 30). Origin of the characteristic electron energy losses in aluminum. Physical Review Letters, 869. doi:http://dx.doi.org/10.1103/PhysRev.115.869 R. M. Dickson et al. J. Phys. Chem. B 104, 6095 (2000). For additional insight into the formal Mathematics and Physics behind SPR, see nanoplasmonic-related articles by: Dr. P. Bienstman, Ghent University Dr. Polman, Amolf University Dr. Shalaev, Purdue University Dr. Peter Debackere, UC-Berkeley

Key Concepts 1. Why should we focus on plasmonic biosensing? Explain using proportionality analysis of electronics and photonics alone. 2. What is a plasmon? 3. Decribe, qualitatively, the electromagnetics behind surface plasmon resonance. 4. What two things make for a good biosensor? 5.How does a SPR Kretschmann-designed biosensor work?