High-sensitivity electrocardiogram sensor based on Fano resonance in a double-stub-assisted plasmonic micro-ring resonator

Abstract

Detecting Electrocardiogram (ECG) signals remains a challenge due to its low signal amplitude and low frequency characteristic. In this paper, we suggest a solution to ECG sensor based on Fano resonance of surface plasma wave (SPW) in a Double-Stub-Assisted plasmonic micro-ring resonator (DS-PMRR) structure by exploiting the electro-optic (EO) effect of EO polymer. A theoretical model of Fano resonance of SPW in DS-PMRR is established to analyze the sensitivity of ECG sensor. A moderately symmetrical cone mode converter is designed to achieve the efficient coupling between silicon on insulator (SOI) waveguide and metal–insulator–metal (MIM) waveguide. The whole structure with an active zone as small as 5 μm × 8.4 μm × 0.2 μm is analyzed by finite-element method (FEM) and a sensitivity of 11740 pm/V is obtained. In combination with a sub-picometer optical spectrum analyzer, the proposed sensor can detect ECG signals with the magnitude on the order of 10 μv.