Direct Laser Writing of Functional Materials for Wearable Human‐Machine Interaction: Mechanisms, Materials, and Applications

ABSTRACT Direct laser writing (DLW) uses tightly confined laser beams to trigger photothermal, photochemical, and ultrafast photophysical processes. It enables mask‐free, sub‐micrometer patterning of functional materials on diverse substrates under ambient conditions. Wide material compatibility, fine feature control, and low heat input make DLW attractive for wearable human‐machine interaction (HMI). These systems are soft, skin‐conformal devices that monitor physiological and environmental signals in real time. This review surveys DLW‐derived materials and architectures for wearable HMI devices. It provides a system‐level perspective and highlights manufacturing‐structure‐property‐performance relationships that guide the design of DLW‐enabled wearables. We first outline the main laser‐material interaction mechanisms, then classify DLW‐derived materials into six families: carbon‐based frameworks, metals and alloys, metal oxides, polymers and composites, 2D materials, and hybrids. For each family, we link manufacturing routes, microstructures, key properties, and device performance. Next, we map these materials onto five building blocks of wearable platforms: sensors, energy modules, communication components, feedback interfaces, and fully integrated systems. We cover mechanical, pressure, strain, humidity, temperature, gas, optical, biochemical, and multimodal sensors. Performance is benchmarked in terms of sensitivity, detection limit and range, response and recovery time, and stability under realistic deformation and wear. Finally, we discuss remaining challenges and future directions. Key issues include throughput and scalability, mechanical durability, biocompatibility, and standards for long‐term reliability. We highlight emerging strategies such as multi‐beam and roll‐to‐roll DLW, hybrid workflows with printing and 3D structuring, sustainable precursors and advanced nanocomposites, and AI‐guided design and process control. Together, these directions aim to accelerate DLW‐enabled wearables from laboratory prototypes to everyday wearable HMI systems.