Inspired by the ubiquitous helical structures in nature, research on artificial helices has attracted increasing attention. As a unique and complex three-dimensional (3D) geometry in the microscopic world, the micro-/nano helix has significant advantages in wide applications due to its distinctive properties at the micro-scale. Micro-/nanotechnology is advancing rapidly. The geometric complexity of helical structure poses technical challenges for the manufacturing at the micro-/nanoscale, requiring some emerging manufacturing techniques. In this review, we systematically classify and summarize existing manufacturing methods for micro/nano helical structures and their underlying mechanisms. Based on the unique physical properties of helical structures at the microscale, their latest applications are analyzed across different fields. Finally, we conclude the challenges and future research directions of micro-/nano helices in manufacturing methods and applications.

Several natural organism can change shape under external stimuli. These natural phenomena have inspired a vast amount of research on exploration and implementation of reconfigurable shape transformation. The Janus structure is a promising approach to achieve shape transformation based on its heterogeneous chemical or physical properties on opposite sides. However, the heterogeneity is generally realized by multi-step processing, different materials, and/or different processing parameters. Here, we present a simple and flexible method of producing pH-sensitive Janus microactuators from a single material, using the same laser printing parameters. These microactuators exhibit reversible structural deformations with large bending angles of ~31° and fast response (~0.2 s) by changing the pH value of the aqueous environment. Benefited from the high flexibility of the laser printing technique and the spatial arrangements, pillar heights, and bending directions of microactuators are readily controlled, enabling a variety of switchable ordered patterns and complex petal-like structures on flat surfaces and inside microchannels. Finally, we explore the potential applications of this method in information encryption/decryption and microtarget capturing.