Programmable direct-patterning assembly enables high-density and surface-conformal integration of fiber Bragg grating sensor arrays.

Fiber Bragg grating (FBG) sensors are widely used in aerospace monitoring and intelligent manufacturing due to their high sensitivity, yet their deployment relies on manual assembly, limiting precision, integration density, and conformality under extreme conditions. Here, we propose a programmable direct-FBG-patterning (DFP) assembly paradigm for one-step integration of intrinsically brittle multiplexed FBG arrays onto arbitrary curved and non-developable surfaces. A mechanics-optics coupled framework identifies three minimum bending radii governed by interfacial debonding, fiber fracture, and optical attenuation, defining the achievable feature size and multidirectional sensing capability. Guided by this framework, cross-fiber routing and conformal assembly strategies enable high-density sensor networks along a single continuous fiber beyond the limits of manual assembly. We further demonstrate robust and versatile FBG sensor integration in applications including structural displacement reconstruction, phonation, and gesture monitoring, establishing a general strategy for quasi-distributed sensing beyond the constraints of manual assembly.