Optofluidic And Particles Capture With Sorting Based On Gold Nanoarray Structure

As a kind of non-contact and high-precision microfluidics control method,optofluidic have extensive application prospect in biology,chemistry and medical treatment.The surface plasmon resonance can occur in gold nanostructure when irradiated by laser with specific wavelength,accompanied by local heating and local field enhancement.Also its optical properties are easily modulated.Therefore,the application of gold nanostructure to realize microfluid control has become a potential optofluidic method.In this paper,we applied nanoarray structures to microchannels and simulated the plasmon resonance of the nanoarray structure under laser irradiation.It provides a theoretical basis for optofluidic based on nanoarray structures.The main research contents are as follows:The temperature rise generated by photothermal conversion based on nanoarray can control the flow in the microchannel.The optical adsorption properties of nanostructures with different structure parameters,laser wavelength and polarization direction of electric field are calculated in this paper,and further the temperature rise of nanoarray structures are calculated quantitatively.Then,the temperature rise data is applied to the microchannel flow model and the corresponding control effect was obtained.The results indicate that the temperature rise have great difference when the laser electric field polarization direction is parallel and vertical array direction at the resonance wavelengths,which is helpful to control the flow control in the microchannels.The temperature rise is applied to the microchannel model,and the process of adjusting the outlet flow of the microchannel by the polarization direction is calculated.In addition,it was found that the temperature rise of nanoparticles in array was different,indicating that the optical absorption properties of particles in array are different.The optical gradient force generated by the local field enhancement effect caused by plasmon resonance is used to capture and sort the nanoparticles.The effects of array spacing and laser wavelength on local field enhancement are investigated.Then,the optical force and optical potential well distribution over nanoarray are calculated by using Maxwell stress tensor method.Considering that nanoparticles are not only affected by optical force,but also by Brownian force and viscous resistance,the particles motion is analyzed systematically and the optical capture effect is explored.A kind of optical sorting device based on nanoarray structures is designed,which can effectively separate nanoparticles with different refractive index and diameter under certain conditions.