Introduction of an angle interrogated, MEMS-based, optical waveguide grating system for label-free biosensing

Abstract

The presented label-free optical biosensor system relies on a MEMS micro-mirror to interrogate waveguide grating regions at a high repetition rate in the kHz range by scanning the angle of the incident coherent light. The angle-tunable MEMS mirror permits an extended scanning range and offers the flexibility to measure at various wavelengths and optical powers – an interesting feature for an enhanced surface-to-bulk sensitivity ratio and extended, multiplexed sensor arrays. An excellent refractometric sensitivity with a limit of detection towards effective refractive index changes of Δneff < 2 × 10−7 and long-term stability (<10−6 min−1) is reported, as well as the capability to perform affinity measurements for large (>150 kDa) and small (<250 Da) molecules. With fully-integrated optics, electronics and fluidics, the compact, low-power and affordable sensor unit is well-suited for in situ environmental monitoring or point-of-care diagnostics.