A novel system for comparing viscosity of two liquids via flow time delays and providing indications about liquid quality, using photo-interrupter sensors and implemented with FPGAs and VHDL

Abstract: A novel system which uses FPGAs and VHDL for comparing viscosity of two liquids, with the first one be- ing the standard liquid and the second being the tested one, is presented here. The system monitors flow delay times of both liquids using two corresponding photo-interrupter sensors. If the opaque liquid goes through sensor slot, sensor transits to HIGH state with simultaneous time value storing. Our system is programed to calculate and display in FPGA board’s seven-segment displays, the signed time values difference of the two liquids, thus indicating whether standard or tested liquid reaches corresponding photo-interrupter sensor first and also what is the magnitude of viscosity differ- ence of the two liquids. A set of output LEDs is also programed to light up, in order to present the level of the above time difference depended viscosity variance of the two liquids. Our algorithm works fine also with transparent liquids as long as liquid flow tubes are sufficiently thick (several millimeters), in order to prevent infrared radiation passing through the liquid. Our system is cheap to manufacture, easy to use and able to process simultaneously, due to FPGA use, a large number of tested liquids in industrial environments, allowing it to produce valid information for liquid samples by combining it with IoT and AI systems.

Keywords: Viscosity, photo-interrupter sensors, liquid flow, FPGA, VHDL, LEDs.