Surface plasma resonance technology (surface plasmon resonance technology, SPR) overview.

. Abstract:
SPR technology as an effective tool for detecting and analyzing biometric interactions, some countries have produced mature commercial SPR sensing systems. The working principle, application field and latest progress of SPR biosensors are expounded, and their application and research prospects in the field of biometric detection are discussed.
Introduction:
Surface Plasma Resonance technology (surface plasmon resonance technology, SPR) is a biometric detection technology developed in the 1990s and is based on a cutting-edge technique for detecting the role of ligations and adlytes on sPR detection biosensor chips.
At the beginning of the 20th century, Wood observed abnormal diffraction when polarization light from continuous
spectral
irradiated metal
grasts
and publicly described it. In 1941, Fano explained this phenomenon using a surface electromagnetic wave excitation model of the metal-air interface.
1957, Ritchie discovered that there was a peak of disappearance as electrons passed through sheet metal. He called the vanishing peak a "reduced energy" plasma pattern and pointed out the relationship between this pattern and the thin film boundary, proposing for the first time the concept of a "metal plasma" to describe vertical fluctuations in the density of electrons inside a metal. Two years later, Powell and Swan used experiments to confirm Ritchie's theory.
, Stem and Farrell gave the resonance conditions of this plasma pattern, which they called "surface plasma resonance technology (surface plasmon resonance, SPR). In 1968, Otto and Kretschmann and others studied the optical excitation of SPR by metal and media interfaces. And the two prism coupling methods are designed separately.
, SPR technology has come a long time. In 1990, the first commercially produced biosensors were born in Biocore, Sweden. Practice has proved that SPR sensors, compared with traditional detection methods, have the advantages of not having to mark samples, real-time monitoring and high sensitivity.
, there are broad application prospects in the fields of medical diagnosis, biological monitoring, biotechnology, drug
and
food safety testing.
principle
1 Vanishing Wave, the Finier theorem describes the path of light on the surface of the medium well before the wave optics develop. (n1 sin1 s n2 sin2), it can be seen that when light is directed from the photocryst medium to the light-sparse medium (n1>n2) there is a full reflection phenomenon.
But when you re-examine the full reflection at a fluctuating optical angle, you will find that the fully reflected light wave will pass through the optical dredging medium at a depth of about one wavelength of light waves, and then flow along the interface at about half the wavelength before returning to the photocryst medium. The total energy of light has not changed. The light wave that penetrates into the optical dredging medium becomes the vanishing wave.2 surface plasma wave; plasma usually refers to a gas consisting of a fairly high density of free positive and negative charges, where the number of positive and negative charged particles is almost equal, and no spatial charge is formed internally. If the price electrons of a metal are regarded as electron gases moving against a uniform positive charge background, this is actually a plasma.
when a metal is subjected to electromagnetic interference, the distribution of electron density in the metal becomes uneven. It is assumed that if the electron density is lower than the average density in an area, a local positive charge excess will be formed.
At this time, due to the gravitational pull of the Coulomb, the electrons attracted to the region, and the electrons attracted by the additional momentum, which in turn causes the region to gather too much negative charge, however, due to the rejection of electrons, the electrons leave the region again, thus forming the price electrons relative to the positive charge background of the ups and downs oscillation.
due to the long-range action of the Coulomb force, this local electron density oscillation will form the vertical collective oscillation of the entire electronic system and be represented in the form of the wave of the density fluctuations. It can be known that the price electrons in the metal are equivalent to this oscillation in the positive ion background, similar to the plasma oscillation in the conductive gas, so it is called the plasma oscillation in the metal.
the same is true of plasma oscillations on the surface, we can see that there is also a certain amount of electron oscillation within them..