One-Dimensional Nanograting-Based Guided-Mode Resonance Pressure Sensor

We report the design, fabrication, and characterization of a high-resolution optical pressure sensor based on guided-mode resonance (GMR) in a titanium dioxide (TiO₂) nanograting embedded in an 85-μm-thick polydimethylsiloxane (PDMS) membrane. The device presented here is capable of resolving changes in pressure as small as 200 mtorr within a PDMS channel. The embedded GMR grating has a pitch distance of 500 nm when the PDMS membrane is unstrained; at this pitch, the grating has a resonance response at around 727 nm, producing a peak in the reflectivity spectrum of the device. When pressure within the channel increases, the membrane is strained, resulting in an increase in the grating pitch as well as its corresponding resonant wavelength. By measuring the resulting change in the reflectivity spectrum of the grating, the device should be able to detect changes in relative pressure throughout a range of over 60 torr.