Real-time monitoring of nanocellulose suspension concentration using a liquid–solid triboelectric nanogenerator

Monitoring and controlling the concentration of nanocellulose suspensions is crucial for various industrial processes. Because of the high complexity of traditional concentration measurement devices, new techniques that offer simple, reliable, and real-time concentration monitoring have been developed. Here, we report a method for real-time concentration monitoring using a tubular structured liquid–solid triboelectric nanogenerator (LS-TENG). The LS-TENG was operated in single-electrode mode with a triboelectric layer comprising a polytetrafluoroethylene tube. Further, we systematically investigated the dependence of the device output performance on variables such as concentration, flow rate, tube diameter, and tube material, finding it to be directly proportional to the flow rate and tube diameter and inversely proportional to the concentration. Furthermore, the output current of the LS-TENG exhibited an exponential relationship with the concentration of the nanocellulose suspension and the Reynolds number, achieving a correlation coefficient above 0.94 for the corresponding regression equation. This study provides a direct, accurate, real-time, and self-powered method for monitoring nanocellulose suspension concentrations.