Research On Biosensor Based On Microwave Metamaterial

Metamaterial is an artificial electromagnetic material that consisted ofsubwavelength unit structure with period arrangment. Permeability and dielectricconstant can be implemented with double negative or single negative. It owns specialelectromagnetic properties different from common natural material, such as negativeCerenkov radiation, negative Doppler effect, negative refraction coefficient and so on.Recently, the split ring resonators (SRRs) have been used for the manufacture ofsensors, which has caught people’s attentions. Compared to the conventional surfaceplasmon resonance and nanomaterials sensing devices, the SRR-based biosensorshave the features of simple preparation process, rapid reaction, and easy process forverification of results, which has potential application value in areas such as clinicalchemistry and diagnosis, bioengineering, food industry, military science,environment monitoring and so on.First of all, this paper summarizes the current research status and hot researchtopic of the metamaterial biosensors after reviewing the related literature at homeand abroad, and establishes the equivalent circuit model of SRRs. The frequencyformula of the split ring resonators is given, and the theoretical calculation resultsusing the formula are compared to the simulated resonance frequency results. Thecompared result shows that there are some errors between the theoretical results andthe simulated results, but it can correctly reflects the influences of the structure sizeon the electromagnetic resonance frequency. Moreover, The structure parameterssuch as opening width, side length, space between inner and outer ring are simulatedto carry out the influence on the resonant frequency. The results show that theresonance frequency increases with the increase of opening width, decreases with theincrease of side length.Secondly, a symmetric SRR-based biosensor, an asymmetric SRR-basedbiosensor, a symmetric SRRs-based biosensor and an asymmetric SRRs-basedbiosensor are designed using the sortware of CST. The Q value, electric fielddistribution of z direction, surface current distribution and sensitivity of the four biosensors are simulated and analyzed, and the results show that the asymmetricbiosensor has a higher Q value, along with higher sensitivity than the symmetric one.Finally, the four types of biosensors are processed and tested. Differentconcentrations of glucose solution are adopted to test the sensitivity of the symmetricand asymmetric SRR-based biosensors. The results show that the asymmetricbiosensor is more sensitive than the symmetric one. When DNA and DNAhybridization are immobilized onto the surface of the symmetric SRRs-basedbiosensor, the shifts of the resonant frequency is obvious, which shows that theSRRs-based sensor can be applied to biological molecules testing.