P8 - Low Cost, Autonomous and Wireless Enabled Liquid Level Sensor Based on a Multi-Segmented Polymer Optical Fiber

SENSOR+TEST Conferences 2011
2011-06-07 - 2011-06-09
Proceedings OPTO 2011
OP - Poster Session
D. Dimas, S. Katsikas - Prisma Electronics S. A, Athens (Greece), C. Riziotis - The National Hellenic Research Foundation, Athens (Greece), A. Boucouvalas - University of Peloponnese, Tripoli (Greece)
145 - 150


The optical sensors’ technology has reached a quite mature level that could enable its successful integration in real demanding applications further to the lab environment. On the applications’ side the development of effective autonomous and wireless sensor networks for industrial monitoring applications sets very strict requirements in the complexity and cost of sensor components and modules in order to make their integration in working environments viable. We have identified suitable photonic architectures for effective employment and propose here a new simple design of low implementation cost as an effective liquid level sensor. Liquid level sensing is of continuous demand in a range of industrial applications from chemical to mechanical areas. Photonic based level sensors offer a new solution of added value, for monitoring and control of industrial environments characterized by excessive electromagnetic noise or interferences, and are suitable also for measuring flammable or explosive liquids (alcohols, gasoline, diesel, etc) as no electric currents re present in the detection.

We propose and demonstrate here a very simple design, as compared to existing alternative POF sensors, based on a multi segmented POF that exhibits better performance at lower cost and complexity, so can be integrated in an autonomous wireless sensing node. The sensor was implemented by creating a discontinuous POF transmission system by aligning fiber segments with gaps in between. Immersing the sensor in a liquid the light propagating path properties change, adjusting accordingly the total light delivered to the photodetector. The level measuring system has an intrinsic discrete behavior making the sensor robust to any imperfections. The functionality could be extended by filling the gaps of fibers with other polymeric materials with enhanced selectivity in hydrocarbons, alcohols, ammonia etc. inducing intrinsic refractive index discrimination characteristics with improved transmission performance and consequently increased measuring range. The sensor was characterized in a variety of liquids showing stable performance and almost a linear output voltage ratio when various measuring points have been immersed in the liquid compared to the signal when no points are in the liquid.