On-chip dual microcombs drive nanomaterial-enhanced fiber sensors for high-selectivity multi-gas mapping

Accurate gas detection is a cornerstone of energy security, environmental monitoring, and medical diagnosis. However, developing a miniaturized device that achieves both high selectivity (distinguishing specific gases) and high sensitivity (detecting trace amounts) has long presented a significant challenge. Traditional spectroscopic methods often struggle to identify complex gas mixtures without relying on bulky equipment or broad spectral bandwidths.

Research group at the University of Electronic Science and Technology of China (UESTC) has achieved a major breakthrough in this field. Published in the journal PhotoniX, their study introduces a compact, all-in-one sensor capable of simultaneously identifying and quantifying multiple gas components with exceptional precision. The team developed a hybrid system that utilizes on-chip Kerr soliton dual-microcombs to drive a string of 12 micro-fiber Bragg grating (µFBG) sensors. A core innovation of the system is its ability to achieve high selectivity through precise nanomaterial functionalization rather than traditional broad spectral sweeping.

Unlike standard chemically inert fiber sensors, the team’s device employs micro-etched fibers coated with specific gas-sensitive nanomaterials, including graphene oxide mixtures, metal nanoparticles, and polymers. “In this scheme, on-chip Kerr soliton dual-microcombs simultaneously drive and demodulate a network of nanomaterial-functionalized detectors,” the researchers explain. By matching each optical comb line to a specific sensor, the system creates a dedicated detection channel for each gas. For instance, a sensor functionalized with WO₃/Pt responds exclusively to hydrogen, while one coated with Gelatin targets humidity. This "lock-and-key" design ensures independent channel responses, granting the system high specificity even in complex environments.

Validated against complex gas mixtures, the system successfully identified 12 distinct components, including H₂, CO, NO₂, NH₃, and ethanol. The synergy between the ultra-stable microcomb sources and the enhanced light-matter interaction on the fiber surface enabled a record-low detection limit of 24.3 parts per billion (ppb) in single-shot measurements. Furthermore, when analyzing a mixture containing 16 different gases, the system maintained high accuracy, limiting measurement error to less than 2.27% for the targeted components.

This work represents a cross-disciplinary leap, merging chip-scale photonics with advanced materials science to create integrated, miniaturized sensing platforms. The technology paves the way for sophisticated “electronic noses” capable of real-time, distributed environmental monitoring and industrial safety analysis.

The paper, “Gas mapping based-on dual microcomb driven nanomaterial functionalized fiber Bragg grating string,” is available in PhotoniX. The research was led by the Key Laboratory of Optical Fiber Sensing and Communications at UESTC, with contributions from Southern Power Grid Sensing Technology and the Institute of Semiconductors, Chinese Academy of Sciences.

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