Peking University School of Physics prepares all-optical sensor based on nano-fiber array

Recently, the research team led by Xiao Yunfeng and the academician Gong Qihuang of the School of Physics of Peking University successfully prepared a plenoptic sensor based on nano-fiber array. The single-particle size resolution of the new sensor reached 10 nm for the first time.

The highly sensitive sensing of particulate matter is of great importance in environmental monitoring, national security and biochemical research. The optical technology-based sensing technology has the advantages of non-physical contact, easy operation and high sensitivity. Therefore, the traditional optical fiber sensor has been "showing its talents" in the field of high-sensitivity detection.

Xiao Yunfeng explained to the Science and Technology Daily reporter: "The international academic research shows that when the diameter of the fiber is reduced to the wavelength of light, a significant evanescent field is generated outside the fiber (the scale is on the order of 100 nanometers), which is weak to the surrounding environment. The change is extremely sensitive, so the scattering and effect of the particles in the evanescent field can be used to measure the sensing and size distribution of ultrafine particles."

According to Xiao Yunfeng, in the new study, they first accurately calculated the relationship between scattering efficiency and scatterer size and fiber diameter, and predicted the optimal geometry and detection limit of nanofiber sensors. Subsequently, high-sensitivity nanofiber arrays were performed. The design and preparation, and by optimizing the fiber mode, enables sensing and measurement of individual standard polystyrene nanoparticles with particle size resolutions up to 10 nm.

The research team used this sensor to continuously monitor the atmospheric fine particles in winter in Beijing in 2015 and 2016, and directly obtained the particle size distribution information and real-time evolution map of fine particles on the 100-nanometer scale. The fine particles calculated based on this data were used. The quality concentration data is in good agreement with the officially published data trend, demonstrating that this result has high application value.

Academician Gong Qihuang said: "Compared with other sensors, nano-fiber type sensing is not only high precision, low cost, simple operation, and easy to carry, it can quickly and accurately detect ultra-fine particles in the atmosphere, and is expected to be environmental protection and Research on the mechanism of haze formation provides a new tool."

This achievement was published in the important optical journal "Light: Science and Application", and the research was supported by the National Natural Science Foundation of China and the Ministry of Science and Technology.