A research group led by ZJUI Professor Huan HU has invented a new way to fabricate a sub-micron spherical atomic force microscope (AFM) tip controllably. A tiny silicon ball mounted on microcantilevers is used to make an AFM for precise nanoscale friction measurements, biological studies, and colloid science. The group demonstrated spheres from 100 nm to 1 μm in diameter, and positioned them with accuracy of 10 nm or better. This AFM tip overcomes a critical challenge of dropping spherical AFM tips into the sub-micron scale. The work appeared in Langmuir, a well-known international journal on interface research, and was highlighted on the cover. 

The procedures for fabricating a sub-micron spherical AFM

The irradiated silicon starts to show swelling under different helium ion dosing

A top-down scanning helium

Dr Tao Jinhui from the Pacific Northwest National Laboratory, USA, commented: “Using spherical swelling of silicon materials under dosing from high-energy helium ion beams, Dr Hu’s research group pioneered the processing of spherical atomic force microscope probes.”

Dr Wei Dongguang, Chief Scientist of Zeiss Microscopy’s ion research and development center, believes that “this research has greatly expanded the range of probe tip materials at a very low cost, thus expanding the detection and characterization capabilities of scanning probe technology.”

This work was supported by the National Natural Science Foundation of China and Natural Science Foundation of Zhejiang Province, Fundamental Research Funds for the Central Universities, Natural Science Foundation of Shanghai, and Tang’s Foundation. The work was also partially supported by Zhejiang University-University of Illinois at Urbana-Champaign Institute.