Hydrogels with micro/nano‐structures precisely prepared by femtosecond‐laser processing technology are biomaterials that mimic the natural extracellular matrix and can achieve the precise regulation of biological properties, such as cell behavior and structural–mechanical properties. They also play a crucial role in biomedical fields such as regenerative medicine, bionanostructural construction, drug transport, and particle manipulation. This study summarizes the central role of the nonlinear absorption property of femtosecond lasers in the preparation of hydrogel micro/nano‐structures. Based on the electron‐dynamics model and electron‐density flood theory, the two main processing types of the femtosecond laser‐processed hydrogel, additive and subtractive manufacturing, are discussed in depth. The modification mechanisms such as the photon–electron energy‐field conversion, multiphoton absorption effect, and bubble‐driven bio‐link molding are analyzed. Additionally, the stimulus‐response diversification and functional biomimicry properties of the structural hydrogels under the influences of different laser action modes and hydrogel composition ratios are investigated for their biomedical applications, such as microactuators, drug delivery, microscaffolds, and the in vitro simulation of vascular networks. On this basis, the advantages and limitations of the current technology are summarized and a reasonable prediction for future research on the law of action of the femtosecond‐laser preparation of hydrogel micro/nano‐structures is made.

Multi-focal microlens arrays provide notable advantages over mono-focal counterparts, such as multi-scale imaging capabilities and optical aberration correction. However, existing multi-focal microlens arrays fabricated on continuous surfaces are incapable of achieving confocal imaging. As a result, multiple focus adjustments are required to acquire comprehensive image data, thereby complicating system design and increasing operational duration. To overcome this limitation, a stepped confocal surface microlens array is proposed, capable of simultaneously capturing images with multiple depths of field, various field-of-view scales, and different resolutions—without the need for additional focus adjustments. A combination of femtosecond laser processing and chemical etching was employed to fabricate microlenses with varying curvatures on a stepped fused silica substrate, which was subsequently used as a mold. The final stepped confocal microlens array was replicated via polydimethylsiloxane (PDMS) molding. Preliminary experimental analyses were carried out to determine the relationship between processing parameters and the resulting focal lengths. By precisely controlling these parameters, the fabricated stepped confocal microlens array successfully enabled confocal imaging, allowing for the simultaneous acquisition of diverse image data. This microlens array shows great potential in advancing lightweight, integrated, and highly stable optical systems for applications in optical sensing, spatial positioning, and machine vision.

This study investigates the effects of current density on the microstructure and properties of electrodeposited NiCo-CeO₂ composite coatings. Results demonstrate that current density significantly influences coating composition, with higher CeO₂ and lower Co content increasing surface roughness (minimum at 30 mA/cm², maximum at 100 mA/cm²). Microstructural homogeneity improves with optimized Co/CeO₂ content, where the A30 coating (30 mA/cm²) exhibits the weakest texture among all coatings due to peak Co incorporation. Texture intensifies at higher current densities (30–100 mA/cm²) as Co and CeO₂ contents diminish. Internal stress depends on electrodeposition kinetics and particle dispersion, ranging from −2.22 MPa (A20) to 651 MPa (A50). Hardness correlates with (111) plane dominance and Co/CeO₂ content, reaching 449.8 HV for A30 but dropping to 288.8 HV for A100. Optimal current density tuning refines grains, enhances (111) texture, and improves compositional uniformity, endowing the A30 coating with balanced hardness and corrosion performance (corrosion potential: −224 mV; current density: 0.225 μA/cm²). These findings provide guidelines for tailoring high-performance NiCo-CeO₂ coatings through current density regulation.