This technology develops in situ real-time QD monitoring techniques for dynamic membrane fouling. The same wavelength of light source arouse different size of quantum dots due to high fluorescence intensity of quantum dots, anti-photobleaching ability, and quantum confinement, thereby obtaining all kinds of color remarks. 
Based on above-mentioned properties, this technology synthesis core-shell quantum dots via wet chemical approaches and modify the surface of core-shell quantum dots in order to possess specific conjunction function. For example, negatively charged oileic acid is connected to CdSe/ZnS Core-Shell quantum dots by tritylphosphine and then dispersed itself in the polyvinylidene difluoride polymeric membrane, thus becoming the quantum dot probe membrane that can effectively detect positively charged pollutants,  such as proteins, amino acids, metal ions and so on. The adopted membrane configuration may include but no restricted to flat, hollow fiber or tubular type.

The utilization of quantum dots probe membrane with spectrometer is able to online detect the membrane fouling. Among these fouling detections, fouling at membrane pore openings could be judged from absorption spectrum with UV/visible spectrophotometer since the fouling deposited at membrane surface could not be adsorbed by quantum dots. The change in amount of fouling adsorbed onto the surface of quantum dots influences fluorescent property and intensity shown from adsorbed quantum dots and consequently determine fouling site. Hence, this technology could effectively provide the fouling information including fouling site, fouling composition, and fouling amount, as well as dramatically break the limits of state-of-the-art detection technologies on account of their presence of immediacy.

This technique offers good opportunities for in-situ real-time monitoring of fouling in the chemical industry, biotechnology, biorefinery, and food sectors. It is now possible to investigate fouling layer thickness, distribution, composition, concentration and structural properties in high resolution and sensitivity, and therefore has considerable potential. This technique can extend the stable operating time and lifetime of membrane, and reduce the operation and maintenance cost of membrane module. Further, this technology has the ability to initiate automated backwashing, an essential requirement for a more widespread use of online monitoring techniques.