Researchers have used a three-dimensional (3D) printing technique to stack nanometre-scale polymer threads on top of one another, forming a tiny wall.
A promising 3D nanoscale printing method involves spinning nanofibres out of a liquid under a strong electrical field. But only certain shapes have been printed this way, because the fibres tend to electrically repel each other. To solve this problem, Minhee Lee and Ho-Young Kim of Seoul National University fired polymer nanofibres onto a metal template sitting on top of a grounding plate that quickly drains the deposited fibres of charge. The fibres then spontaneously attract each other, and stack to form a free-standing wall.
The technique cannot yet be used to print objects with sharp corners but could still be useful for building, for example, tiny transistors, the authors say.