Chinese brushes: From controllable liquid manipulation to template-free printing microlines

As a traditional writing instrument for calligraphy and painting, the Chinese brush has enjoyed a high reputation over the last 5, 000 years due to its ability to controllably handle liquid ink, and has been widely used to deposit ink into certain characters or figures as a means of cultural communication. In this mini-review, we first show how the key to the controllable liquid transfer in a Chinese brush lies in the anisotropic multi-scale structural features of the freshly emergent hairs. Then, drawing inspiration from this, applications in controllable liquid pumping, highly efficient liquid transfer and template-free printing microlines are addressed. We envision that the fundamentals of Chinese brushes and their applications in liquid manipulation mentioned in this review may also be extended to other liquid phase functional material systems.