Comprehensive review of distributed acoustic sensing technology: principles, configurations, applications and emerging trends
In recent years, distributed acoustic sensing (DAS) has been a preferred choice in many practical applications due to its versatility and the possibility of using existing infrastructure. This paper presents a thorough review on DAS technology of all aspects of such sensing system. The review includes a market overview demonstrating the increasing trend in DAS market size (projected to USD 7.8 billion by 2030), focused on implementation in different fields. Then, the operation principles, fundamentals and theoretical background of the DAS systems are analyzed and compared in terms of different approaches. In addition, the myriads of DAS applications proposed in recent years are reviewed. Thereafter, current limitations and drawbacks of DAS are discussed and emerging technologies to address such drawbacks are analyzed in terms of benefits and future challenges for the next generation of DAS technology. This review paper’s unique value is to comprehensively cover all aspects of DAS technology, from its theoretical basis and first laboratory demonstrations to practical implementation covering tens of kilometers. Such review can be used as a roadmap for DAS applications and to understand the application and implementation of ϕ-OTDR systems with critical perspective of the new possibilities of the next generation of DAS systems.
Characterization and functional evaluation of a fiber-optic instrumented impedance-controlled upper-limb exoskeleton
The use of active exoskeletons for musculoskeletal disorder (MSD) prevention is increasing in industrial environments. Wearable sensing technologies enable closed-loop control of these devices. However, magnetic disturbances and sensor fixation issues can compromise measurement reliability and affect exoskeleton behavior. Polymer optical fiber (POF) sensors offer intrinsic immunity to electromagnetic interference and mechanical compliance, making them a promising alternative for wearable kinematic sensing. Nevertheless, their integration within the control loop of active exoskeletons remains largely unexplored. This study investigates the impact of POF sensing modality integrated within the impedance control loop of an upper-limb exoskeleton, focusing on control performance and system dynamics. A two-stage experimental protocol was conducted under an approved ethical protocol. First, a test-bench evaluation showed that POF sensing modality achieves comparable rise time and mean absolute error to IMU sensing modality, though it resulted in a 0.565 s increase in settling time. Second, participants performed standardized lifting tasks under assisted (Exo-POF and Exo-IMU) and unassisted (No-Assist) conditions. Kinematic and electromyographic (EMG) data showed a 16–23% reduction in muscle activation while preserving range of motion. These findings demonstrate that POF sensing modality significantly influences system dynamics and human–robot interaction. Subsequently, the proof of concept suggests the feasibility of the proposed approach during lifting, handling, and lowering tasks, opening the way for future validation under representative industrial environments.