Multichannel detection using transmissive diffraction grating sensor

Abstract

AbstractWe report a novel transmissive diffraction grating pH sensor made of pH‐sensitive hydrogel. The sensor provides inherently multichannels for a flexible selection of different detection ranges, without involving any additional tuning mechanisms or using multiple sensing elements. Each transmitted diffraction order from the hydrogel grating forms an individual detection channel dedicated to a specific pH range. This unique feature is achieved, simply by enabling hydrogel ridges of the grating to swell effectively in lateral directions, while inhibiting the ridges from swelling in vertical direction and keeping grating period unchanged. Thus by looking at different diffraction orders and measuring their intensity ratio, it is possible to achieve tunable dynamic detection range. Besides, this approach can lead to a high‐sensitivity sensor for detecting subtle pH variations in a narrow pH range near the volume‐phase transition point of hydrogel, with the resolution at the level of 10−3 pH units. © 2011 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2011