Flexible and stretchable guided-mode resonant optical sensor: single-step fabrication on a surface engineered polydimethylsiloxane substrate

We present an unconventional yet simple and effective surface re-engineering method to hydrophilize the polydimethylsiloxane (PDMS) surface for the direct fabrication of a flexible and stretchable guided mode resonance (GMR) sensor. It enables us to directly spin coat photoresist as a planar waveguide on a PDMS substrate without any oxygen or UV treatment. To fabricate a GMR structure, a 1D grating is surface-patterned on this coated photoresist layer through Lloyd mirror interference lithography. A sensing experiment is performed with the obtained GMR structure and is validated by FDTD simulations. The sensor performance is consistent over repeated measurements, making the PDMS surface highly resistant to hydrophobic recovery.