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 wave guide 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 Delta n(eff)< 2 x 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. (C) 2015 Elsevier B.V. All rights reserved.