Individual nanoparticles can be picked up and placed on a surface using dip-pen nanolithography
Dip-pen nanolithography is a patterning technique in which the tip of an atomic force microscope can be used to 'write' on a surface by transferring the material or 'ink' with which it is coated to a substrate. However, although dip-pen is convenient and direct, the existing 'dipping' procedure is limited to picking up large numbers of ink particles. Now, Jun Hu and co-workers1 at the Chinese Academy of Sciences in Shanghai have found a way to use the dip-pen method to pick up and place individual nanoparticles.
Initially, gold nanoparticles are deposited from solution onto a mica substrate. With the microscope tip, the team then identifies a small region on the substrate containing only one nanoparticle and lowers the tip, in 1 nm steps, to pick it up. Once the tip has grabbed the nanoparticle, it can be deposited at a new position using the same set of operations.
In addition to gold, Hu and co-workers can also manipulate single quantum dots and magnetic particles and show that the nanoparticles can be moved on a number of different surfaces. This straightforward approach may have applications in the design of quantum-dot devices.
References
Wang, Y. Zhang, Y. Li, B. Lu, J. & Jun, H. Capturing and depositing one nanoobject at a time: single particle dip-pen nanolithography. Appl. Phys. Lett. 90, 10.1063/1.2714287 133102 (2007).
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Cheung, F. One at a time. Nature Nanotech (2007). https://doi.org/10.1038/nnano.2007.130
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DOI: https://doi.org/10.1038/nnano.2007.130