Study On Rapid Label-free Detection Of Biomolecules Solution Based On Metamaterials

In the traditional radio-frequency sensing scheme,the sample can only be detected under drying condition.The biological activity of the biomolecules,such as cells,is decreased after drying,thus the electrical properties are changed,which affect the final results.For the purpose of detecting the dielectric characteristic of biomolecule solution or liquid in the radio-frequency band,this thesis proposes a radio-frequency biosensor which bases on the symmetrical metamaterial components as resonant structure.To begin with,the research background of metamaterial structure based biosensor is introduced.Then,the operating principle of the resonant biosensor,the designing scheme of the resonant metamaterial transmission line,as well as the combination process between the resonance structure and the biological solution are well explained.The thesis describes four aspects including the effective medium,the half-wavelength resonator,the left-hand medium and the metamaterial transmission line as the theoretical foundation to design a biosensor in detail.By coupling via the pure resonance method or the mixed method of a split-ring resonator(SRR)or a complementary split-ring resonator(CSRR),transmission lines of various types could be acquired.Moreover,the designing scheme of the biosensor based on the structure of nested split-ring resonator(nSRR)is also proposed.The effects of the dielectric constant,the thickness,and the cover location of the tested solution to the biosensor are verified by simulations.Finally,the process of manufacturing and measurement calibration of the new-type biosensor are illuminated.The measurement results of the resonant frequency of a biosensor bare slice are in accordance with corresponding simulation results,thereby verifying the correctness of the simulation results.Experimental tests using liquid samples of Polydimethysiloxane(PDMS)are also developed,and the results are compared with corresponding simulation results.In summary,by using the impedance matching method,and has designed a radio-frequency biosensor that bases on the symmetrical metamaterial components as resonant structure,the biosensor may be utilized for fast detection of label-free biomolecule solution.The experimental results of the biosensor bare slice match well with the simulation results,and validate the correctness of both the theory and the designing scheme.Through measurement experiments of the liquid samples of PDMS,it can be preliminarily proved that the biosensor is able to speculate the dielectric characteristic of the tested biomolecule liquid or solution,by measuring the variations of the resonance frequency before and after adding the tested sample.