New-Type Biosensor Based on Multiple Total-Internal Reflections in Heterodyne Interferometry

In this paper, a novel biosensor based on multiple total-internal reflections (MTIRs) in heterodyne interferometry (HI) is proposed. The biosensor is made of an elongated prism. As a heterodyne optical light source transmits through the new-type biosensor, it will undergo multiple total-internal reflections (MTIRs). Thus we can obtain the text signal at the output. The phase difference variation due to the different refractive indices of the tested media can be obtained by a Lock-In-amplifier (LIA). By some numerical calculations, we can achieve the related parameters of the tested medium. The resolution of the sensor can reach 4x10(-7) refractive index unit (RIU). The electro-optical biosensor has some merits, easy operation, in real-time measurement, and high stability, etc.