Direct laser lithography (DLL) is a key enabling technology for 3D constructs at the microscale and its potential is rapidly growing toward the development of active microstructures. The rationale of this work is based on the different involved methodology, which is referred as indirect, when passive microstructures become active through postprocessing steps, and direct, when active structures are directly obtained by fabricating microstructures with active materials or by introducing heterogeneous mechanical properties and specific design. An in‐depth analysis of both indirect and direct methods is provided. In particular, the wide range of materials and strategies involved in each method is reported, including advantages and disadvantages, as well as examples of fabricated structures and their applications. Finally, the different techniques are briefly summarized, and critically discussed by highlighting how the new synergies between DLL and active materials are opening completely new scenarios, in particular for sensing (e.g., mechanical) and actuation at the microscale.

Polyelectrolyte layer-by-layer (LbL) nanofilms are interesting polymeric structures, built by alternating adsorption of positively and negatively charged polyelectrolytes. They consist of multilayer sheets with nanometric overall thickness, and they can be used as supports and surface coatings for in vitro and in vivo cell and tissue growth and regeneration. The present study focuses on nanofilms based on alternated layers of poly(sodium-4-sulfonate) (PSS) and poly(allylamine hydrochloride) (PAH) fabricated using spin-assisted LbL assembly (SA-LbL). The fabrication process used to assemble polyelectrolyte nanofilms made of up to 60 bilayers is described, and the influence of different surface charges (i.e. changing the terminal layer) and of different film composition (e.g. varying PSS molecular weight) on cell behaviour is investigated. In particular, C2C12 skeletal muscle cells' viability, proliferation and differentiation on six different typologies of polyelectrolyte nanofilms are evaluated and quantified, giving a reference for skeletal muscle regeneration capabilities on such kind of structures.