Label-Free Water Sensors Using Hybrid Polymer-Dielectric Mid-Infrared Optical Waveguides

Keywords

drop-cast coating; gradient refractive index; hybrid polymer-dielectric waveguides; label-free detection; mid-infrared absorption; sensor on-a-chip

Abstract

A chip-scale mid-IR water sensor was developed using silicon nitride (SiN) waveguides coated with poly(glycidyl methacrylate) (PGMA). The label-free detection was conducted at λ = 2.6-2.7 μm because this spectral region overlaps with the characteristic O-H stretch absorption while being transparent to PGMA and SiN. Through the design of a hybrid waveguide structure, we were able to tailor the mid-IR evanescent wave into the PGMA layer and the surrounding water and, consequently, to enhance the light-analyte interaction. A 7.6 times enhancement of sensitivity is experimentally demonstrated and explained by material integration engineering as well as waveguide mode analysis. Our sensor platform made by polymer-dielectric hybrids can be applied to other regions of the mid-IR spectrum to probe other analytes and can ultimately achieve a multispectral sensor on-a-chip.

Publication Date

6-3-2015

Publication Title

ACS Applied Materials and Interfaces

Volume

7

Issue

21

Number of Pages

11189-11194

Document Type

Article

Personal Identifier

scopus

DOI Link

https://doi.org/10.1021/acsami.5b01013

Socpus ID

84930628159 (Scopus)

Source API URL

https://api.elsevier.com/content/abstract/scopus_id/84930628159

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