Polymer distributed Bragg reflectors for label-free vapor sensing

• Main Author: Lova, Paola
• Other Authors: Cesare Soci
• Format: Theses and Dissertations
• Language: English
• Published: 2017
• Subjects: DRNTU::Science::Physics::Optics and light
• Online Access: http://hdl.handle.net/10356/69541
• Institution: Nanyang Technological University

Colorimetric sensors are of great interest for on-site detection of volatile organic compound vapors in urban and industrial areas. Thanks to their simple structure, distributed Bragg reflectors (DBR) are widely researched for the development of lab-on-a-chip sensors. Among them, polymer DBR with narrow stop-bands and large analyte adsorption possess strong optical response to small concentration of chemicals, allowing sensitive detection even by naked eye. Notwithstanding their sensitivity, low vapor permeability and need for chemical labelling to achieve selectivity hinder the use of polymer DBR for vapor pollutants. In this thesis, we developed new polymer DBRs able to overcome these issues. Highly permeable nanocomposites made of polystyrene loaded with inorganic nanoparticles were used to increase permeability, yielding sensitivity down to 0.5 ppm. Label-free selectivity was also achieved exploiting vapor induced crystallization of poly (p-phenilenoxide) embedded into DBR sensors. These results promise a new generation of low-cost, sensitive and selective lab-on-a-chip detectors that are easy to operate and do not require additional instrumentation.