A nanopipette enables manipulation of nano-matters in fluids

Abstract

The ability to print and manipulate nanoscale objects affects diverse fields as materials science, nanotechnology, and biomedicine. Although many scientists and engineers have continually developed clever and high-precision techniques, new methods are still in great demand for different materials and geometries. Here I will present nanopipette-assisted methods for single particle manipulation and 3D printing: 1) scanning-aperture electrostatic tweezers and 2) meniscus-guided 3D printing. First, I will discuss an interesting finding that surface charges of glass nanopipettes can be used to pick and place single charged nanoparticles at will in a fluid [1]. This technique, scanning-aperture electrostatic trap, enables contact-free, size-independent trapping of very small single nanoparticles. The application to fundamental study on plasmonics will also be discussed [2]. Second, I will discuss a meniscus-guided 3D printing method that exploits a mechanically flexible liquid meniscus formed at a pipette-substrate gap to 3D print functional materials at the micro/nanoscale. This technique can be successfully applied to various materials such as polymers [3,4], graphene [5], metals [6], CNTs [7], and soft microbubbles [8]. [1] J. T. Kim et al, Nat. Commun. 5, 3380 (2014) [2] Y. Tuna, J. T. Kim et al, ACS Nano 11, 7674 (2017) [3] J. T. Kim et al, Adv. Mater. 23, 1968 (2011) [4] M. Chen et al, ACS Nano 12, 4172 (2018) [5] J. H. Kim et al, Adv. Mater. 27, 157 (2015) [6] S. K. Seol et al, Small 11, 3896 (2015) [7] J. H. Kim et al, ACS Nano 10, 8879 (2016) [8] J. T. Kim et al, ACS Macro Lett. 7, 1267 (2018)