Simple, reliable, lightweight, and inexpensive thin films based sensors are still in intense development and high demand in many applications such as biomedical, industrial, environmental, military, and consumer products. One important class of sensors is the optical pH sensor. In addition, conformal thin film based sensors extend the range of application for pH optical sensors. We present the results on the fabrication and characterization of optical pH sensing coatings made through ionic self-assembled technique. These thin films are based on the combination of a polyelectrolyte and water-soluble organic dye molecule Direct Yellow 4. A series of films was fabricated and characterized in order to determine the optimized parameters of the polymer and of the organic dye solutions. The optical pH responses of these films were also studied. The transparent films were immersed in solutions at various temperature and pH values. The films are stable when immersed in solutions with pH below 9.0 and temperatures below 90 °C and they maintain their performance after longer immersion times. We also demonstrate the functionality of these coatings as conformal films.

Date Published: 16 April 2016
PDF: 8 pages
Proc. SPIE 9802, Nanosensors, Biosensors, and Info-Tech Sensors and Systems 2016, 98021Q (16 April 2016); doi: 10.1117/12.2219386

Published in SPIE Proceedings Vol. 9802:
Nanosensors, Biosensors, and Info-Tech Sensors and Systems 2016
Vijay K. Varadan, Editor(s)