Smart textiles for personalized healthcare

There is nothing more personal than healthcare. Health care must move from its current reactive and disease-centric system to a personalized, predictive, preventative and participatory model with a focus on disease prevention and health promotion. As the world marches into the era of Internet of Things (IoT) and 5G wireless, technology renovation enables industry to offer a more individually tailored approach to healthcare with more successful health outcomes, higher quality and lower costs. However, empowering the utility of IoT enabled technology in personalized health care is still significantly challenged by the shortage of cost-effective and wearable biomedical devices to continuously provide real-time, patient-generated health data. Textiles have been concomitant and playing a vital role in the long history of human civilization. In this talk, I will introduce our current research on smart textiles for biomedical monitoring and personalized diagnosis, textile for therapy, and textile power generation as an energy solution for the future wearable medical devices.

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Smart Textiles for Personalized Health Care

Heteroatom-doped polymers or carbon nanospheres have attracted broad research interest. However, rational synthesis of these nanospheres with controllable properties is still a great challenge. Herein, we develop a template-free approach to construct cross-linked polyphosphazene nanospheres with tunable hollow structures. As comonomers, hexachlorocyclotriphosphazene provides N and P atoms, tannic acid can coordinate with metal ions, and the replaceable third comonomer can endow the materials with various properties. After carbonization, N/P-doped mesoporous carbon nanospheres were obtained with small particle size (≈50 nm) and high surface area (411.60 m2  g-1 ). Structural characterization confirmed uniform dispersion of the single atom transition metal sites (i.e., Co-N2 P2 ) with N and P dual coordination. Electrochemical measurements and theoretical simulations revealed the oxygen reduction reaction performance. This work provides a solution for fabricating diverse heteroatom-containing polymer nanospheres and their derived single metal atom doped carbon catalysts.

Cross-Linked Polyphosphazene Hollow Nanosphere-Derived N/P-Doped Porous Carbon with Single Nonprecious Metal Atoms for the Oxygen Reduction Reaction

In this work, 3D highly electrically conductive cellulose nanofibers (CNF)/Ti3C2Tx MXene aerogels (CTA) with aligned porous structures are fabricated by directional freezing followed by freeze-drying technique, and the thermally annealed CTA (TCTA)/epoxy nanocomposites are then fabricated by thermal annealing of CTA, subsequent vacuum-assisted impregnation and curing method Results show that TCTA/epoxy nanocomposites possess 3D highly conductive networks with ultralow percolation threshold of 020 vol% Ti3C2Tx When the volume fraction of Ti3C2Tx is 138 vol%, the electrical conductivity ( ), electromagnetic interference shielding effectiveness (EMI SE), and SE divided by thickness (SE/d) values of the TCTA/epoxy nanocomposites reach 1672 S m-1, 74 dB, and 37 dB mm-1, respectively, which are almost the highest values compared to those of polymer nanocomposites reported previously at the same filler content In addition, compared to those of the samples without Ti3C2Tx, the storage modulus and heat-resistance index of TCTA/epoxy nanocomposites are enhanced to 97925 MPa and 3107°C, increased by 62% and 69°C, respectively, presenting outstanding mechanical properties and thermal stabilities The fabricated lightweight, easy-to-process, and shapeable TCTA/epoxy nanocomposites with superior EMI SE values, excellent mechanical properties, and thermal stabilities greatly broaden the applications of MXene-based polymer composites in the field of EMI shielding

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3D Shapeable, Superior Electrically Conductive Cellulose Nanofibers/Ti3C2Tx MXene Aerogels/Epoxy Nanocomposites for Promising EMI Shielding.

The artificial skin-like stretchable ionic sensor device usually requires a synergistic effect of reliable adhesion between human machine interface, reasonable mechanical strength, and visually displayable transparency. A plant-inspired zwitterionic hydrogel was prepared through rapid UV initiation in the existence of cellulose nanocrystals as physically crosslinker and reinforcing agent. The resulting transparent zwitterionic nanocomposite hydrogel successfully brings the synergistic advantages of robust adhesive strength between diversified substrates such as skins, plastics, glass, and steels with remarkable mechanical properties of a superior stretchability over 1000% strain, a mechanical tensile strength up to 0.61 MPa, and compressive strength up to 7.5 MPa, manifesting in superior ionic transport performance, simultaneously. Furthermore, the zwitterionic nanocomposite hydrogel was fabricated as a wearable compliant stretchable pressure-strain sensor in the modality of the skin-adhesive patch to be sensitive to human motion such as finger touch and speech recognition for personal healthcare of patient sensory rebuilding and physiological data acquisition. It maintains compressive cycling sensibility at diverse pressure during 0.5, 1.0, and 1.5 Hz, respectively. The multifunctional zwitterionic nanocomposite hydrogel could also be assembled into flexible electrical devices such as luminescent display and information transfer between human and robot communication for mechanosensory electronics and artificial intelligence.

Highly Stretchable, Adhesive, and Mechanical Zwitterionic Nanocomposite Hydrogel Biomimetic Skin

Wearable sensor technologies, especially continuous monitoring of various human health conditions, are attracting increased attention. However, current rigid sensors present obvious drawbacks, like lower durability and poor comfort. Here, a strategy is proposed to efficiently yield wearable sensors using cotton fabric as an essential component, and conductive materials conformally coat onto the cotton fibers, leading to a highly electrically conductive interconnecting network. To improve the conductivity and durability of conductive coatings, a topographical modification approach is developed with genus-3 and genus-5 structures, and topological genus structures enable cage metallic seeds on the surface of substrates. A textile-based capacitive sensor with flexible, comfortable, and durable properties has been demonstrated. High sensitivity and convenience of signal collection have been achieved by the excellent electrical conductivity of this sensor. Based on results of deep investigation on capacitance, effects of distance and angles between two conductive fabrics contribute to the capacitive sensitivity. In addition, the textile-based capacitive sensor has successfully been used for real-time monitoring human breathing, speaking, blinking, and joint motions during physical rehabilitation exercises.

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Textile-Based Capacitive Sensor for Physical Rehabilitation via Surface Topological Modification.

Flexibility plays a vital role in wearable electronics. Repeated bending often leads to the dramatic decrease of conductivity because of the numerous microcracks formed in the metal coating layer, which is undesirable for flexible conductors. Herein, conductive textile-based tactile sensors and metal-coated polyurethane sponge-based bending sensors with superior flexibility for monitoring human touch and arm motions are proposed, respectively. Tannic acid, a traditional mordant, is introduced to attach to various flexible substrates, providing a perfect platform for catalyst absorbing and subsequent electroless deposition (ELD). By understanding the nucleation, growth, and structure of electroless metal deposits, the surface morphology of metal nanoparticles can be controlled in nanoscale with simple variation of the plating time. When the electroless plating time is 20 min, the normalized resistance (R/R0 ) of as-made conductive fibers is only 1.6, which is much lower than a 60 min ELD sample at the same conditions (R/R0 ≈ 5). This is because a large number of unfilled gaps between nanoparticles prevent metal films from cracking under bending. Importantly, the Kelvin problem is relevant to deposited conductive coatings because metallic cells have a honeycomb-like structure, which is a rationale to explain the relationships of conductivity and flexibility.

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A Nature-Inspired, Flexible Substrate Strategy for Future Wearable Electronics.

Eddy current methods are wildly used for measuringthe electromagnetic property of ferromagneticsamples due to its high sensitivities and portability (when using the remote electromagnetic sensor). However, in diverse applications, the eddy current measurement is always hampered by the lift-off variation – the gap between the sensing probe and the sample. In this paper, the measurement error of the permeability caused by the lift-off variation could be significantly reduced when using a developed planar triple-coil sensor. An inverse algorithm, the single-frequency eddy current algorithm is established for the evaluation of the permeability by referring to the phase of themeasured impedance or inductance. Based on the experiments of several ferromagnetic samples when using the developed sensor and inverse algorithm, the measured permeability is proved can be almost immune to the lift-off variations.

Measurement of Ferromagnetic Slabs Permeability Based on a Novel Planar Triple-Coil Sensor

The liftoff spacing distance between the eddy current (EC) sensor and the test piece will influence the detected signals and accuracy of the measurement. Various techniques including novel sensor designs, features (liftoff point of intersection, liftoff invariance phenomenon), and algorithms have been proposed for the compensation of error caused by the liftoff effect using the EC sensor. However, few of these have directly measured the liftoff spacing distance, particularly for the distance up to 15 mm. In this article, a liftoff tolerant pancake sensor has been designed. By analyzing the sensitive region of the magnetic vector potential change (due to the test piece), the receiver of the sensor is designed as a circular spiral pancake coil with a large mean radius and span length (the difference between inner and outer radius). Experiments on the inductance measurement of three different nonmagnetic samples have been carried out using both the designed pancake sensor and the previous triple-helix sensor. From the experiment results, the detected signal of the designed sensor has been proven much larger than that of the triple-helix sensor. Besides, simplified algorithms have been proposed for the measurement of the liftoff spacing and thickness of non-magnetic samples when using the proposed pancake sensor. Results show that the liftoff spacing and thickness can be measured with a small error of 0.14 mm (absolute error under 209.66 kHz), and 1.35% (relative error, under low working frequencies of 142, 238, and 338 Hz) for the liftoff spacing from 1 to 15 mm.

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Liftoff Tolerant Pancake Eddy-Current Sensor for the Thickness and Spacing Measurement of Nonmagnetic Plates

Wearable sensor technologies attract increasing attention for continuous monitoring of human health. Much effort is devoted to exploit well‐designed materials to realize superior abilities, such as high sensitivity, stability, and responsiveness. However, it hardly meets huge demands for practically wearable applications simply focusing on the development of sensing materials in isolation. Comprehensive consideration is given from upstream materials to endure market, including materials design, sensor assembly, signal analysis, theoretical foundation, and final system performance, such as sensitivity, stability, responsiveness, cost, comfortability, and durability. Herein, a systematic design is presented that combines a conductive fiber fabrication based on surface nanotechnology, device assembly process optimization, signal acquisition and analysis, and theoretical simulation, through a new multidisciplinary strategy integrating material science, textile technology, electromagnetics, and electronic engineering. The as‐constructed magnetic inductance sensing system shows approximately six‐times inductance change with regard to joint bending motions during rehabilitation exercises. This integrated design strategy offers a new concept, namely, a whole sensing system design, for wearable technologies in real‐time health monitoring applications.

https://onlinelibrary.wiley.com/doi/pdf/10.1002/aisy.201900037

Liming Chen

Papers

Textile-Based Capacitive Sensor for Physical Rehabilitation via Surface Topological Modification.

A Nature-Inspired, Flexible Substrate Strategy for Future Wearable Electronics.

Measurement of Ferromagnetic Slabs Permeability Based on a Novel Planar Triple-Coil Sensor

Liftoff Tolerant Pancake Eddy-Current Sensor for the Thickness and Spacing Measurement of Nonmagnetic Plates

Whole System Design of a Wearable Magnetic Induction Sensor for Physical Rehabilitation