Distributed sensing along fibers for smart clothing Brett C. Hannigan, Tyler J. Cuthbert, Chakaveh Ahmadizadeh, Carlo Menon Textile sensors transform everyday clothing into a means to track movement and biosignals in an unobtrusive way. A major challenge in adopting "smart" clothing is the difficulty of connections and space when scaling up the number of sensors. There is a lack of research addressing the key limitation in wearable electronics: connections between rigid and textile elements are often unreliable, and they require interfacing sensors in a way incompatible with textile mass production methods. We introduce a prototype garment, compact readout circuit, and algorithm to measure localized strain along multiple regions of a fiber. We use a helical auxetic yarn sensor with tunable sensitivity along its length to selectively respond to strain signals. We demonstrate distributed sensing in clothing, monitoring arm joint angles from a single continuous fiber. Compared to optical motion capture, we achieve around five degrees error in reconstructing shoulder, elbow, and wrist joint angles. This work presents a distributed strain sensing approach that replaces discrete interconnects and electronics in the garment with single-fiber sensors. The sensing fibers themselves should ideally consist of the same materials as the bulk garment, preferentially using biodegradable or easily separable polymers, and be made with cleaner fabrication processes. Continuous fibers able to sense at multiple points along their length that can be woven or knit into fabric would greatly reduce connection issues, allow greater sensor density, potentially increase sustainability, and maintain compatibility with established textile processes. Distributed sensing is a promising solution to the problems encountered when scaling up strain and pressure sensing garments. A distributed sensing system permits multiple measurements out of a single sensor element, each localized in space. Unlike approaches using multiple sensors connected by wires, multiplexers, or switches, the electrical connectivity is greatly simplified. Distributed sensing can also be used to increase sensitivity, allow arbitrarily high spatial resolution, and simplify two-dimensional pressure or strain sensitive arrays. We demonstrate a system to enable distributed sensing along a strain sensor and a prototype garment that monitors the three major arm joint angles with one continuous sensing fiber. Our solution isolates the single pair of connections to one end of the stretchable fiber, so that the fiber may be sewn or woven into a textile without connections or wires in the fabric. This fiber sensor design allows the single remaining connection to be centralized at one end in a proximal hub location. It compares favorably to some other fiber strain sensor designs that require wires from both ends or access to an inner layer (e.g., coaxial capacitive fibers), which brings much greater complexity to textile manufacturing. We developed a compact electronic impedance analyzer circuit to collect high-speed impedance measurements at multiple frequencies in parallel and use this device to develop an algorithm and test fixture to quantify strain reconstruction performance more rigorously. We show the application of a single-fiber capacitive sensor with tunable sensitivity at different locations alongDistributed sensing along fibers for smart clothing Brett C. Hannigan, Tyler J. Cuthbert, Chakaveh Ahmadizadeh, Carlo Menon Textile sensors transform everyday clothing into a means to track movement and biosignals in an unobtrusive way. A major challenge in adopting "smart" clothing is the difficulty of connections and space when scaling up the number of sensors. There is a lack of research addressing the key limitation in wearable electronics: connections between rigid and textile elements are often unreliable, and they require interfacing sensors in a way incompatible with textile mass production methods. We introduce a prototype garment, compact readout circuit, and algorithm to measure localized strain along multiple regions of a fiber. We use a helical auxetic yarn sensor with tunable sensitivity along its length to selectively respond to strain signals. We demonstrate distributed sensing in clothing, monitoring arm joint angles from a single continuous fiber. Compared to optical motion capture, we achieve around five degrees error in reconstructing shoulder, elbow, and wrist joint angles. This work presents a distributed strain sensing approach that replaces discrete interconnects and electronics in the garment with single-fiber sensors. The sensing fibers themselves should ideally consist of the same materials as the bulk garment, preferentially using biodegradable or easily separable polymers, and be made with cleaner fabrication processes. Continuous fibers able to sense at multiple points along their length that can be woven or knit into fabric would greatly reduce connection issues, allow greater sensor density, potentially increase sustainability, and maintain compatibility with established textile processes. Distributed sensing is a promising solution to the problems encountered when scaling up strain and pressure sensing garments. A distributed sensing system permits multiple measurements out of a single sensor element, each localized in space. Unlike approaches using multiple sensors connected by wires, multiplexers, or switches, the electrical connectivity is greatly simplified. Distributed sensing can also be used to increase sensitivity, allow arbitrarily high spatial resolution, and simplify two-dimensional pressure or strain sensitive arrays. We demonstrate a system to enable distributed sensing along a strain sensor and a prototype garment that monitors the three major arm joint angles with one continuous sensing fiber. Our solution isolates the single pair of connections to one end of the stretchable fiber, so that the fiber may be sewn or woven into a textile without connections or wires in the fabric. This fiber sensor design allows the single remaining connection to be centralized at one end in a proximal hub location. It compares favorably to some other fiber strain sensor designs that require wires from both ends or access to an inner layer (e.g., coaxial capacitive fibers), which brings much greater complexity to textile manufacturing. We developed a compact electronic impedance analyzer circuit to collect high-speed impedance measurements at multiple frequencies in parallel and use this device to develop an algorithm and test fixture to quantify strain reconstruction performance more rigorously. We show the application of a single-fiber capacitive sensor with tunable sensitivity at different locations along