CN105004698B - A kind of Biosensors Based on Surface Plasmon Resonance device - Google Patents

Abstract

A surface plasmon resonance biosensor consists of a prism, a nanoparticle array, a silicon dioxide film, graphene, and a sample cell. The nanoparticle array is located on the lower surface of the prism, and the silicon dioxide film covers the nanoparticle array. The graphene is covered on the silicon dioxide film, and it is characterized in that: the prism is a high refractive index material, and the nanoparticle array is composed of polystyrene nanospheres coated with a metal film. The invention belongs to the field of nano science, uses the principle of SPR to excite SPP on the lower surface of metal, and the small change of the sample refractive index can affect the resonance curve and change the resonance angle. On the contrary, the refraction index of the sample can be deduced from the detected resonance angle, and then the concentration of the substance to be measured can be obtained accurately.

Description

A Surface Plasmon Resonance Biosensor

technical field

The invention relates to a novel surface plasmon resonance biosensor, which belongs to the scientific fields of nanotechnology and biotechnology.

Background technique

In recent years, the research on metal surface plasmons (SPPs) has made great progress. SPP refers to the collective oscillation of free electrons on the surface of metal micro-nano structures induced by an external electromagnetic field (such as light waves). It has a prominent feature that it can realize surface plasmon resonance (Surface Plasmon Resonance, SPR). Thousands of times bigger. Therefore, the interaction effect between the electric field and the substance can be greatly improved, and it is widely used in the field of biosensing, and has become a powerful technical means for people to analyze the concentration of substances. The invention proposes a new type of SPR sensing technology, which uses nanospheres covered with metal film as a sensing unit and is encapsulated with graphene, which has the characteristics of high sensitivity and wide application range.

Contents of the invention

The technical problem to be solved by the present invention is to overcome the deficiencies of the prior art and provide a novel surface plasmon resonance biosensor with high sensitivity, wide application range and economical price.

Technical solution of the present invention is:

A novel surface plasmon resonance biosensor consists of a prism (1), a nanoparticle array (2), a silicon dioxide film (3), graphene (4) and a sample cell (5), and the nanoparticle array ( 2) Located on the lower surface of the prism (1), the silicon dioxide film (3) covers the nanoparticle array (2), graphene (4) covers the silicon dioxide film (3), and the prism (1) is a high The refractive index material, the nanoparticle array (2) is composed of polystyrene nanospheres (6) coated with a metal film (7).

The prism (1) is a material with a higher refractive index than the silicon dioxide film (3), and has low loss relative to incident light, preferably heavy flint glass or selenium oxysulfide glass or silicon.

The polystyrene nanospheres (6) have a diameter of 50nm to 80nm and are arranged in a single layer next to each other.

The material of the metal thin film (7) is gold, silver or aluminum, and the thickness is 10nm-80nm.

The thickness of the silicon dioxide film (3) is between 10 nm and 0.25 times the incident wavelength.

The number of layers of the graphene (4) is 1-8 layers.

Compared with the prior art, the present invention has the following advantages:

1. Ultra-high sensitivity. Compared with the traditional biosensor, the sensitivity of the SPR biosensor designed by the invention is improved by nearly one order of magnitude.

2. The detection range of substances to be tested is wide. The biosensor overcomes the disadvantage of limited physical state of the sample to be tested, can detect both liquid state and gas state, and has a wide range of applications.

3. Long service life. Graphene has a strong anti-oxidation ability, which can protect the metal layer from oxidation and corrosion, and increase the service life of the sensor.

4. Wide operating wavelength. The prism material selected in the present invention has a wide operating wavelength and can detect samples in different wave bands.

Description of drawings

Fig. 1 is a structural representation of the present invention;

Figure 2 Surface plasmon resonance peak

Figure 3 The formant shift of the test sample

detailed description

The present invention will be further described below in conjunction with drawings and embodiments.

As shown in Figure 1, the present invention is made up of prism (1), nanoparticle array (2), silicon dioxide film (3), graphene (4) and sample cell (5), and nanoparticle array (2) is positioned at prism On the lower surface of (1), the silicon dioxide film (3) is covered on the nanoparticle array (2), and the graphene (4) is covered on the silicon dioxide film (3). When the prism (1) is heavy flint glass, the metal film (7) is silver, the thickness h is 10nm, the silicon dioxide film (3) thickness is 25nm, and when the graphene (4) thickness is 0.34nm, it is used for incident wavelength 700nm surface plasmon resonance sensor.

When incident with a TM polarized 700nm laser light source, it reaches the nanoparticle array (2) after being refracted by the prism (1). When the incident angle is greater than the critical angle of total reflection, an evanescent wave is generated at the interface of the prism (1) and the nanoparticle array (2), and the evanescent wave will excite a surface plasmon resonance mode. When the thickness h of the metal thin film (7) covered on the polystyrene nanosphere (6) is 10nm-80nm, the resonance mode can be significantly enhanced, and its effect is similar to that of a nanosphere shell. When the resonance occurs, the local electric field increases, the incident light is absorbed, the energy of the reflected light drops sharply, and the surface plasmon resonance peak appears on the reflection spectrum, as shown in Figure 2. The resonance peak is very sensitive to the change of the refractive index of the sample. When the refractive index of the sample adsorbed by graphene (4) changes, the position of the resonance peak will change to realize the detection of the sample, as shown in Figure 3. The dielectric constant of graphene (4) has a large imaginary part, which is an order of magnitude larger than that of Ag in the visible light band. This leads to increased loss at surface plasmon resonance, causing a broadening of the resonance peak, which reduces the accuracy of the sensor. A silicon dioxide film (3) is added between the metal film (7) and the graphene (4) to adjust the equivalent dielectric constant of the film system, and the thickness is between 10 nm and 0.25 times the incident wavelength.

Concrete manufacturing steps of the present invention are as follows:

a. uniformly coating the polystyrene nanosphere dispersion on the lower surface of the prism to form a single-layer nanosphere array next to each other; b. using magnetron sputtering in a vacuum environment to coat a metal film on the nanosphere array on the lower surface of the prism, Thickness is 10nm~80nm; c. Using liquid phase deposition (LPD) to grow silicon dioxide film on metal silver or aluminum film, the film thickness is 10nm~0.25 times the incident wavelength; d. Using chemical vapor deposition (CVD) Grow graphene with a thickness of 0.34nm to 2.72nm; e. Clean and dry to complete the production.

Claims (3)

1. A kind of 1. Biosensors Based on Surface Plasmon Resonance device, by prism (1), nano-grain array (2), silica membrane (3), graphene (4) and sample cell (5) composition, nano-grain array (2) are located at the lower surface of prism (1), and silica is thin Film (3) is covered on nano-grain array (2), and graphene (4) is covered on silica membrane (3), it is characterised in that：Prism (1) it is high-index material, nano-grain array (2) is cladded with metallic film (7) by polystyrene nanospheres (6) and formed；

   A diameter of 50nm~the 80nm of the polystyrene nanospheres (6), individual layer is close to arrangement；

   The metallic film (7) is covered on polystyrene nanospheres (6), is 10nm~80nm apart from nanosphere top thickness h, Material is gold or silver or aluminium；

   Silica membrane (3) thickness is between 10nm and 0.25 times of incident wavelength.
2. 2. Biosensors Based on Surface Plasmon Resonance device according to claim 1, it is characterised in that：Described prism (1) It is more than the material of silica membrane (3) for refractive index, and is low-loss relative to incident light, is dense flint glass or seleno oxygen Sulphur glass or silicon.
3. 3. Biosensors Based on Surface Plasmon Resonance device according to claim 1, it is characterised in that：The graphene (4) The number of plies is 1~8 layer.