3D Nanoprinting with Charged Aerosol Particles─An Overview

Abstract

ConspectusThree-dimensional (3D) printing is a revolutionary technology allowing rapid, cost-effectively, and flexible design of desired 3D products. In this regard, various techniques for downscaling 3D printing have been developed based on several methodologies in the past decades to exploit the advantages of 3D printing at the micro/nanoscale. The development of 3D nanoprinting techniques has provided a method to design unique and sophisticated nanoscale 3D objects enabling functional applications that are thus far constrained with conventional planar nanomanufacturing processes such as photolithography and electron beam lithography. However, the versatile and practical realization of 3D nanoprinting in a broad science and engineering field remains challenging due to limitations such as feature size resolution, suitable materials, and design flexibility. Therefore, innovative 3D nanoprinting techniques are required to overcome current limitations. In this Account, we describe our achievements in developing 3D nanoprinting with charged aerosols relying on the physics behind counteracting electric fields. We introduce the generation of charged aerosols, the most feasible in the broad range of fundamental building blocks (mainly all types of metals and alloys, their oxides, polymers, and organics) for 3D nanoprinting. Moreover, charged aerosols can be processed at ambient conditions easily. The aerosols could be precisely controlled and delivered for the assembly, using electric fields of complicated configurations despite the Brownian diffusion and other chaotic processes. The converging electric fields are formed around openings by the interactions of two electric fields. One of the electric fields comes from a negatively biased substrate. In contrast, the counteracting electric field comes from the positive ions distributed on a prepatterned dielectric layer over the substrate. As a result, the positively charged aerosols are focused through these fields to grow with nanoscale resolution only in the openings of the layer. Furthermore, a growing structure itself could reconfigure the electric field, producing self-focusing nonlinear effects shaping the printed structure. By lifting the layer over the substrate and translating the latter according to a 3D motion program, we created charged aerosol jets that self-focus on the tips of the growing structure and could print diverse 3D forms. The aerosol jets are also capable of writing on the substrate. The 3D nanoprinting produced using the described approach enables the development of the intricate 3D nanostructures described in the Account in detail, including their material characterization and diverse applications. Finally, we concluded and outlined current challenges and future developments of the 3D nanoprinting with charged aerosol particles.