In Vol. 3, Issue 5 of Advanced Photonics Nexus, a new research paper titled "Multimodal Fiber Antenna for Proximity and Stress Sensing" introduces an innovative fiber sensor design by Merve Gokce, Eilam Smolinsky, Louis van der Elst, in collaboration with our collaborators at Cook Medical, Jillian Noblet and Creasy Clauser Huntsman. This publication, previously presented by Merve Gokce at SPIE Photonics West 2024, explores the use of multimaterial fibers for real-time monitoring of both local fiber deformation and environmental changes, such as proximity to foreign objects. In addition, this work selected as the cover art of the publication.
Smart polymer-based monofilament fibers are a promising emerging technology with diverse applications. These fibers derive their unique capabilities from their ability to integrate multimaterial architectures within the fiber, enabling them to sense various environmental, physiological, and biomechanical stimuli. Their flexibility and ability to package intricate devices into a thin, long form make them ideal for human-computer and human-robot interactions.
This paper focuses on a multimodal fiber antenna that offers real-time environmental and physiological monitoring. The fiber can sense a range of parameters, such as pressure, temperature, proximity, blood pressure, and body temperature. It also has potential applications in human-robot interactions, gesture control, and cyber-physical systems like networking and communication.
The study on multimodal fiber antenna sensors for pressure and proximity sensing uses Time-Domain Reflectometry (TDR) to measure local deformations and environmental changes along a fiber. The TDR technique sends a high-speed electromagnetic pulse along the fiber, and the reflected signal provides information about changes in pressure or proximity at various locations on the fiber.
The fiber sensor uses two modes for detection: the symmetric mode and antisymmetric mode. The symmetric mode, which is more sensitive to environmental changes but less responsive to fiber deformation, interacts with the fiber’s surroundings through a large evanescent field. In contrast, the antisymmetric mode, localized between the two wires, is more responsive to fiber deformations but less sensitive to environmental factors.
The TDR measures these deformations and proximity changes by analyzing the time delay of reflected signals, which relate to changes in the fiber's impedance. This delay is calculated using the effective refractive index of the fiber, and the voltage change is influenced by the local physical changes, such as the addition of weight (pressure sensing) or alterations in the dielectric environment (proximity sensing).
The cover image showcases these fibers designed to monitor physiological data with high sensitivity and spatial resolution, making them ideal for demanding medical applications. These fibers also enhance the functionality of textiles and apparel for secure cyber-physical interfacing, as well as improving environmental and situational awareness for surveillance purposes.
