Integrated microfluidic-based sensor module for real-time measurement of temperature, conductivity, and salinity to monitor reverse osmosis

• We fabricated a microfluidic sensor module for monitoring reverse osmosis.
• It can measure temperature, conductivity, and salinity.
• It can reduce sensor manufacturing costs and operating costs for monitoring.
• Product water is effectively monitored using the module.
• The measurement error relative to a reference sensor was less than 8% over five days.

This paper proposes an integrated microfluidic-based sensor module for real-time monitoring of reverse osmosis (RO) that measures temperature, conductivity, and salinity. Current methods suffer from high operating costs because of the amount of instrumentation required and the labor involved in taking real-time readings at each step of the RO process. This sensor module allows for lower manufacturing costs and lower operating costs for the RO process, because it makes remote monitoring of the process at the base station possible. The microfluidic device is constructed from a thin metal film and a microfluidic channel that was fabricated using the microelectromechanical system (MEMS) technology, and it can simultaneously measure both temperature and conductivity. It includes a power board for the generation of an AC voltage signal and DC power from a 9 V battery, a sensing board for microfluidic-based measurement, and a mote for wireless communication. To verify the effectiveness of the sensor module, we used it to monitor the product water harvested from a seawater desalination plant over a five-day period. The encouraging results indicate that the proposed sensor module could be used to monitor industrial RO processes in the near future.