| Surface plasmon resonance(SPR)biosensor,as an optical sensor,has more advantages than traditional methods(such as ELISA)in detecting biomolecular interactions,such as low sample consumption,label-free and real-time detection.Although SPR sensors are currently commercialized,most of the products in the market are expensive and bulky,which limits the application of point-of-care testing(POCT).In recent years,the demand for non-laboratory scenarios such as antibiotic content in outdoor water and particulate content in outdoor air has gradually increased.Therefore,SPR biosensors that get rid of the huge volume is of the great significance for POCT and even clinical testing in the future study.This paper presents a portable multi-channel surface plasmon resonance(SPR)biosensor device.It is based on prism by wavelength interrogation.There is no rotating part,so the instrument is more stable.The design purpose of multi-channel is to improve the detection efficiency.In addition,the accuracy of detection can be improved,when the reference channel is introduced.The propagation properties of electromagnetic waves are introduced firstly in this article.The reflection of light on the surface of the dielectric layer is also analyzed.With the sensing theory of SPR technology,the causes and resonance conditions of surface plasmon waves are analyzed.And the basic principle of spectrometer is introduced as the foundation for a small spectroscopic system.In terms of instrument structure,the volume of the device is compressed as much as possible for each part.Firstly,a cost-effective white light-emitting diode is chosen to be coupled and collimated with optical fibers.They are constructed as a broad-spectrum light source with small size and stable light emission.Secondly,in the sensing part,the prism material and gold film thickness required for the experiment are determined by Macleod software simulation.And the production of single and multi-channels is completed.Finally,a simple,compact and cost-effective spectroscopic component is designed,which can simultaneously detect multiple channels reflection spectral information.The final design size of the instrument is 21 cm×17 cm×6 cm(L×W×H).After the SPR sensor finished,Na Cl solutions with various sample concentrations are used to verify the performance of the biosensor.In the experiment,reflected light intensity under s-polarization and p-polarization state is compared.The reflectance at each wavelength is calculated as SPR curve.The problem of inconsistency of the wavelength light intensity get solved.SPR dip is the wavelength corresponding to the lowest point of the SPR curve.The change of the substance is analyzed by detecting the SPR dip shift.The linear detection range is 4.32×10-2 refractive index unit(RIU),and the limit of detection is 6.38×10-5 RIU.In the multi-channel experiment,the reference channel is introduced and the calculated relative standard deviation(RSD)of each group of experimental data is less than 1%.Finally,a variety of concentrations of immunoglobulin G(Ig G)binding experiments are performed.The experiment finds that there is good linear response at100-400?g/m L.In the course of the adsorption kinetics of Ig G,it is found that the SPR dip rapidly increases after adding Ig G,and then slowly rises to an equilibrium state.It takes about 25 minutes to reach reaction equilibrium each time.The rapid rise course is due to the system response caused by the change of the physical properties(such as the refractive index)of the added sample.And the slow rise course is due to the change in the refractive index of the substance caused by the interaction of Ig G and Anti-Ig G on the sensing layer. |
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