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Introduction of Surface Plasmon Resonance [Part 1]

Updated: Jul 29, 2023

Surface Plasmon Resonance 

표면 플라즈몬 공명

글쓴이: Alex Jang

작성일: 2014년 1 월 3일 (수정일: 2020년 5월 30일)

A simple definition of SPR would be "a phenomenon in which the electron cloud (collective) on the surface of a metal film and an external stimulus (light energy) resonate under specific environmental (conditions)." This sentence contains a lot of physics terminology and is expressed concisely, making it difficult to understand even after reading it several times.

While observing the above image, let me explain a phenomenon that we can directly see with our own eyes.

Let's consider the yellow gold chip in the above image as a mirror. If we shine a laser beam onto the mirror (or incident it) from any angle, the light will be reflected. This is a commonsense phenomenon. However, if we attach a cylindrical lens called a prism in the direction that the light enters the mirror, as shown in the image, and incident the light while changing the angle of incidence from 0 to 90 degrees, we can observe a phenomenon where the light disappears at a certain angle, as if the incident light has been absorbed by the gold chip. This phenomenon is called the SPR phenomenon.

The device that utilizes this phenomenon is called an SPR biosensor. Such devices, filled with physical terminology, are mainly used in the field of biology/chemistry today.

When researchers obtain data using an SPR biosensor, understanding the principles of the SPR phenomenon and sensing is important to obtain better results and to interpret them correctly. Therefore, knowing the basic principles of the SPR phenomenon and sensing is important.

There are many different sensing methods that utilize SPR phenomenon. To avoid confusion, I will focus on the SPR sensing principle of the Kretschmann configuration (angle-interrogation) SPR method. Kretschmann was one of the initial researchers in SPR and the configuration shown in the above image is his invention. While the first person to publish a paper on SPR was Wood, Kretschmann is better known, because most current SPR devices follow his method. This method has the advantage of being stable and achieving high sensitivity in obtaining results.

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