Hybrid Substrates for Real-Time SERS-Based Chemical Sensors

Abstract

Since the discovery of the surface-enhanced Raman scattering (SERS) effect, numerous substrate designs have been proposed for a variety of analytical applications. Although many of these have offered exceptional electromagnetic enhancement, the durability and reusability of substrates have not always been acceptable for routine analytical use. This paper discusses the design and testing of a new class of hybrid SERS substrates specifically designed to optimize electromagnetic enhancement while also affording exceptional ruggedness and reversibility of response under challenging conditions. Substrate templates are fabricated lithographically into a quartz surface, then a thin metal film is deposited, and finally the entire surface is coated with a protective layer. Examples of inorganic and organic protective coatings are provided. Analytes are measured in flowing streams of airborne vapor and aqueous liquid. Properly designed surface coatings serve a dual role as both a protective layer and as a rapidly reversible selective adsorbent for specific analytes.