A Flexible and Stretchable MXene/Waterborne Polyurethane Composite-Coated Fiber Strain Sensor for Wearable Motion and Healthcare Monitoring

Abstract

Fiber-based flexible sensors have promising application potential in human motion and healthcare monitoring, owing to their merits of being lightweight, flexible, and easy to process. Now, high-performance elastic fiber-based strain sensors with high sensitivity, a large working range, and excellent durability are in great demand. Herein, we have easily and quickly prepared a highly sensitive and durable fiber-based strain sensor by dip coating a highly stretchable polyurethane (PU) elastic fiber in an MXene/waterborne polyurethane (WPU) dispersion solution. Benefiting from the electrostatic repulsion force between the negatively charged WPU and MXene sheets in the mixed solution, very homogeneous and stable MXene/WPU dispersion was successfully obtained, and the interconnected conducting networks were correspondingly formed in a coated MXene/WPU shell layer, which makes the as-prepared strain sensor exhibit a gauge factor of over 960, a large sensing range of over 90%, and a detection limit as low as 0.5% strain. As elastic fiber and mixed solution have the same polymer constitute, and tight bonding of the MXene/WPU conductive composite on PU fibers was achieved, enabling the as-prepared strain sensor to endure over 2500 stretching–releasing cycles and thus show good durability. Full-scale human motion detection was also performed by the strain sensor, and a body posture monitoring, analysis, and correction prototype system were developed via embedding the fiber-based strain sensors into sweaters, strongly indicating great application prospects in exercise, sports, and healthcare.

Combinatorial Bionic Hierarchical Flexible Strain Sensor for Sign Language Recognition with Machine Learning

“…We compared the main sensing performances of our sensor to those of other piezoresistive flexible strain sensors, as shown in Figure f. The CBH-sensor exhibits high performances between balancing sensitivity and wide sensing range, outperforming the serpentine or wrinkles/cracks piezoresistive strain sensors ,− reported in the literature to the best of our knowledge (Table S2, Supporting Information). Although the sensitivity or sensing range is lower than that of some strain sensors based on new material or architecture designs, they still cannot handle well to achieve a trade-off between sensitivity and the sensing range.…”

MXene-Based Chemo-Sensors and Other Sensing Devices

“… Schematic illustration of the crack propagation mechanism behind MXene-based strain sensors. Reprinted from [ 54 ]. …”

Multi-Layer Polyurethane-Fiber-Prepared Entangled Strain Sensor with Tunable Sensitivity and Working Range for Human Motion Detection

“…Fiber-based strain sensors, as important components of textile biomechanical sensors, exhibit advantages such as small size, light weight, fast response, and accurate detection of the applied strain on the attached object [13][14][15][16]. Researchers have designed various material structures to achieve strain-sensing performance [17][18][19][20]. The main strategy involves anchoring nanoscale safe and harmless conductive materials (such as carbon Polymers 2024, 16, 1023 2 of 13 nanotubes (CNTs), Graphene, MXene) onto the surface or within the elastic material (fiber, porous material) through hybridization, impregnation, and assembly methods [21,22].…”