OICC Press International Journal of Biophotonics and Biomedical Engineering (IJBBE) 2980-9037 1 1 2021 07 01 Design of Biosensor for Diagnosis of Bio-molecules Using Surface Enhanced Raman Spectroscopy 29 34 10.30495/ijbbo.2021.686484 EN Babak Hassanshahi Department of Electrical and Electronic Engineering, Islamic Azad University, Tabriz Branch, Tabriz, Iran Sayyedjavad Sayyedfattahi Department of Electrical and Electronic Engineering, Islamic Azad University-Tabriz Branch, Tabriz, Iran Journal Article 2021 07 01 In recent years, surface enhanced Raman Spectroscopy (SERS) method have been applied in the area of biotechnology, nanotechnology and diagnostic issues. For that, nanoparticles have been arranged near the flat film structure. By doing so, it is found that the local field enhancement can be greatly improved. In this paper, using two type of nanoparticles namely Ag, Au, we have obtained a double resonance system structure. The process is carried out by the application of nanoparticles, Ag and Au with Ag as a grating coupler. The space and interspace of 3 nm and 5-20 nm for the two particles Au and Ag are considered, respectively. A double resonance system structure has been proposed and simulated with the LUMERICAL FDTD. Our result show that for nanoparticle-film coupling, the highest enhancement factor of 〖(10〗^13) can be obtained for Ag nanosphere and Ag-grating coupler. Finally the simulation results show that application of multiple couplings associated with Ag grating filed and tooth like binding of Ag grating coupling can be used to significantly improve the near-field enhancement.