Web-based refractive index monitoring system for biological solution, employing LPG-FBG hybrid optical sensors

A web-based refractive index monitoring system has been designed and implemented for such a biological solution as sucrose solution for bioethanol production, and the system performance was examined. The LPG-FBG hybrid configuration was adopted as the sensor, because both of the refractive index and the temperature should be monitored generally in such a solution. The LPG was fabricated by using a CO2 laser, and the temperature and refractive index coefficients were measured to be used for the monitoring. The monitoring system was configured such that the monitored data were sent to a computer machine via a web server, and the data were processed by an application in the machine. The application could output the time dependent values of the refractive index or the concentration of a constituent in the solution, and the values are sent to user's web browser to show the monitored values in an on-line graph. Thus, the monitoring system worked over the world-wide-web. The monitoring function of the system was examined by sensing the refractive index changes of a liquid with known physical values, when the liquid temperature changed. The results clarified that the refractive index changes were monitored successfully by the system function.