Functional nanosurface for enhancing optical brain signal by fNIRS system

J.H. Kim, M.Y. Jeong
Pusan national university,

Keywords: plasmonic, nanostructure, enhancement, optical signal


The brain image and brain computer interface is the field that many researcher study mainly and many country invest. The brain activity imaging were detected by many method including Electron Encephalography(EEG), Magnetic Resonance Imaging(MRI), functional near-infrared Spectroscopy (fNIRS). These systems use electromagnetic wave to detect brain activation. For example, the fNIRS system uses a NIR laser to measure brain activation by measuring changes in hemoglobin and deoxyhemoglobin differences. But the contrast with hemoglobin and deoxyhemoglobin is too low to discriminate the smaller part of brain activity. [1,2] Surface plasmon refers to the collective oscillation of quantized electrons occurring between the interface between a metal having a negative dielectric constant and a dielectric having a positive dielectric constant. Surface plasmon is most important part in biology and chemical field to detect more smaller molecules. The structure can gather the electromagnetic field in one spot due to surface plasmon theory. [3,4] In this paper, we designed and fabricated new plasmonic nanostructure to gather fNIRS optical signal by using imprint process for etch-free. The new proposed nanostructure can get the surface plasmon effect in one spot using antenna theory and grating structure which can gather selective wavelength. These structures can detect more weak difference between hemoglobin and deoxyhemoglobin to enhance electromagnetic field in one spot. The enhancement of optical signal by using proposed surfaces can be embedded in certain part of bio imaging system.