This document discusses plasmonic biosensors and their applications. It begins with an abstract stating that plasmonic nanostructures have been used for biosensing applications due to their sensitivity to refractive index changes. It then provides sections on biosensors, plasmonics, plasmonic biosensors, localized surface plasmon resonance sensing, and propagating surface plasmon resonance sensing. Specific applications discussed include the detection of human liver tissues, human blood groups, and hemoglobin concentration in human blood using plasmonic biosensors. The document concludes that the incorporation of biosensors with plasmonics is an important development that could revolutionize medical applications.

1. VIVEKANANDHA
COLLEGE OF ENGINEERING FOR WOMEN
(AUTONOMOUS)
DEPARTMENT OF ELECTRICAL AND ELECTRONICS
ENGINEERING
BIOSENSORS BASED ON PLASMONICS
GUIDED BY: PRESENTED BY:
S.PRABHADEVI S.PAVITHRA
Assistant Professor/EEE
S.S.MANIYAMMAI
P.THILOTHAMA
II-EEE

2. CONTENTS:
 ABSTRACT
 BIOSENSORS
 PLASMONICS
 PLASMONIC BIOSENS
 LOCALIZED SURFACE PLASMON RESONANCE (LSPR) SENSING
 PROPAGATING SURFACE PLASMON RESONANCE (PSPR)SENSOR

3. ABSTRACT:
Because of the sensitivity to refractive index
changes, Plasmonics nanostructures have been
investigated broadly for the bio-molecules detection
through the excitations of the propagating surface
Plasmon resonance (PSPR) or localized surface Plasmon
resonance (LSPR). PSPR sensors can detect sub-
monolayer quantities of bio-molecules at the gold film
surface and provide real-time data through continuous
optical measurements. LSPR sensors could be more
sensitive to local refractive index changes and the
factors of nano particle material, shape and size are all
interrelated and contribute to the refractive index
sensitivities.

4. BIOSENSORS:
 A sensor that integrates a biological element with a
physiochemical transducer to produce an electronic
signal proportional to a single analytic which is then
conveyed to a detector.
 It is a analytic device which converts biological response
into an electrical signal.
 It detects, records ,and transmits information regarding a
physiological change or process.
 It determines the presence and concentration of a
specific substance in any test solution.

5. PLASMONICS:
 Plasmonics is a rapidly developing field at the boundary of physical
optics and condensed matter physics.
 Plasmonics is the study of the interaction of light and metal under
precise circumstance
 Plasmonics is thought to embody the strongest points of both optical
and electronic data transfer , allowing the fast transmission of
information over very small wires.
 The term ‘PLASMONICS’ is derived from plasmons.

6. PLASMONIC BIOSENSOR:
 The most common plasmonic biosensor principle is refractometric
detection.
 When a molecule binds to the surface, the refractive index changes.
All molecules of interest have a refractive index which is higher
than water.
 The properties of the plasmon are changed because they depend on
the refractive index close to the metal.
 By optical spectroscopy, changes in intensity of light for different
wavelengths can then be detected. The resonance shifts in the
spectrum.
 This holds both for surface plasmons (the SPR technique) and nano
particle plasmons

7. To be cont.,
 Plasmonic biosensors can be roughly divided into two classes of
sensing platforms:
 Those that use thin metallic films.
 Those that use individual inorganic plasmon resonant
nanostructures.
 Within each class there are many sensing modalities and also there
are examples of sensing platforms that combine both classes of
sensors.
 By far the most widely used type of plasmonic biosensor is known
to most people simply as “surface plasmon resonance” (SPR), a film
based sensor, and has become the “gold standard” for characterizing
interactions between biomolecules.

8. Localized Surface Plasmon Resonance
(LSPR) sensing
 Localized surface Plasmon resonances are highly susceptible to
their dielectric environment and show pronounced red-shifts of the
Plasmon resonance as the refractive index of the surrounding
medium is increased.
 Due to the strong confinement of LSPRs, the field enhancement
around the plasmonic structure is limited to the near field, with
decay lengths in the order of a few tens of nanometers (depending
on the resonance wavelength and the nanostructure itself).
 Therefore LSPR-based sensors are only sensitive to changes in the
immediate environment of the nanoparticles and less sensitive to
bulk refractive index changes than SPP-based sensing platforms.
 The sensor response is largely dominated by “hot-spots”, the
regions around the nanostructures where the field enhancements are
maximized.
 In optimizing the sensor performance, it is important to maximize
the sensing volume and the contact area with the sensing solution,
as these parameters determine the final sensor sensitivity.

9. schematic overview of an LSPR sensing experiment on a gold nano disk.
The extinction spectra are shown for the bare gold nano disk (1), the disk
fictionalization with a self-assembled monolayer (SAM)(2), antibodies
coupled to the SAM (3) and antigens captured by the antibodies (4).

10. APPLICATIONS:
Plasmonic biosensors are used for:
 Detection of human-liver tissues
 Detection of human blood group
 Detection Of Hemoglobin Concentration In
Human Blood

11. Characterization of sensor
performance
 The most important parameters that quantify the sensor performance for
plasmonic sensors based on refractive index changes.
 Some of these parameters are inherent to the plasmonic structure, while
others show a strong dependence on the surface fictionalization and the
chemical reactions that take place in (bio-) sensing experiments.
 The tunability of Plasmon resonances can be exploited in optimizing the
sensor performance.
 The intrinsic properties of the Plasmon resonance play a key role in the
efficiency of the sensor for practical applications.
 The geometric design of the Plasmon resonator determines the position of
hot spots and its accessibility for the analytic solutions.
 A proper design of the plasmonic structure results in high values for the
sensitivity (S): the observed red shift of the Plasmon resonance () per
refractive index unit (RIU), which is given in units of nm/RIU.

12. PROPAGATING SURFACE PLASMON
RESONANCE (PSPR)SENSOR
 PSPR sensors usually induce SPR on the noble metal surface
through an optical prism.
 Meanwhile, SPR is a powerful surface analytical technique because
it can detect sub-monolayer quantities of bimolecular at the gold
film surface and provide real-time data through continuous optical
measurements
 The sensitivity of the SPR based biosensor coated by a layer of
grapheme can be enhanced greatly compared to the conventional
SPR biosensors .
 In addition, PSPR shows a strong dependence on the angles of the
incident light, which indicates that we can realize the concrete
detection by scanning angles at a certain wavelength.

13. TO BE CONT.,
 The sensitivity largely depends on the nanostructure and takes
different values for different plasmonic modes.
 Larger values for S are expected for plasmon resonances at longer
wavelengths.
 Each plasmonic mode is also characterized by a certain line width ()
which is defined as the full width at half maximum value of the
plasmon line shape.
 The line width is a measure for the damping of the plasmon
resonance, which depends strongly of the nature of the plasmon
resonance.
 Dipolar modes radiate strongly and the resulting line widths are
broad while dark higher order modes radiate less and the resulting
line widths are much more narrow.
 As the line width also strongly depends on the resonant wavelength,
a emph{quality factor (Q-factor)} of the resonance is introduced,
which is given by the ratio of the resonant wavelength and its width.

14. TO BE CONT.,
 The value of the Q-factor determines the line width of the plasmon
resonance (relative to its spectral position) and higher Q-factors
allow to observe smaller spectral shifts of plasmon resonances with
increased accuracy.
 Therefore in terms of sensing the sensor performance is often
expressed in a Figure Of Merit (FOM), which relates the line width
to the sensitivity of the sensor.
 The FOM is in general a good measure for the intrinsic sensor
performance, and higher FOM values allow a more accurate
determination of the resonance position, which implies that smaller
spectral shifts can be observed.
 The smallest refractive index change () that can be observed with
the sensor, which is called the detection limit (DL) and expressed in
RIUs.

15. DETECTION OF HUMAN-LIVER
TISSUES:
 Plasmonic biosensors based on birefringent solid core
micro structured optical fiber is applied for detection of
human liver tissues.
 Such as normal N, metastatic MET , non-cancerous
metastatic(NMET), hepatocellular carcinoma (NHCC).
 The befringent behavior is obtained by removing five
central air holes of a two-ring hexagonal lattice of hole
in a gold covered silica fiber with the liver layer
surrounding the fiber
 By comparing the refractive index obtained we can
distinguish the normal and malignant liver tissue.
 .

16. DETECTION OF HUMAN
BLOOD GROUP:
 Plasmonic biosensors based on birefringent solid core
micro structured optical fiber is applied for detection of
human liver tissues
 The befringent behavior is obtained by removing five
central air holes of a two-ring hexagonal lattice of hole
in a gold covered silica fiber with the blood layer
surrounding the fiber.
 The sensing performance of two resonant modes are
analysed
 By comparing the refractive index obtained wa can
distinguish the different blood group.

17. DETECTION OF HEMOGLOBIN
CONCENTRATION IN HUMAN BLOOD:
 Plasmonic biosensors based on
birefringent solid core or a partial-solid-
core microstructure optical fiber is applied
for detection of hemoglobin
concentration in human blood

18. CONCLUSION
 Incorporation of vital biosensor with
plasmonic is a great step.
 Plasmonic biosensor in the field of
medicine is a great revolution since it
can be transplanted to human body.
 It is multidisciplinary

19. ANY QUERIES