Design and fabrication of enhanced polymer waveguide platforms for absorption-based optical chemical sensors

The development of mass-producible polymer waveguide chips as enhanced platforms for absorption-based optical chemical sensors employing thin colorimetric films is reported here. The chip design is based on a previously reported theoretical study relating to the optimization of the sensitivity of optical absorption-based sensors employing a single reflection configuration. Here, the theoretical analysis is extended to a multiple reflection configuration in order to determine the dependence of sensitivity on interaction length, and the findings are investigated experimentally. The existence of the optimum sensing conditions predicted by theory is demonstrated empirically by examining the pH response of polymer waveguide platforms coated with a sol-gel derived sensing layer doped with a colorimetric pH indicator. This work has major implications for the fabrication of miniaturized, disposable sensor platforms that demonstrate enhanced sensitivity when compared with those utilizing more commonly employed optical configurations.