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PolyU Researchers Develop Intelligent Activewear for a Dry and Comfortable Experience

The Paris 2024 Summer Olympic Games are just around the corner and a global sports frenzy is underway. However, intense summer workouts often lead to sportswear absorbing excessive sweat, becoming clingy and cumbersome, causing discomfort and potentially impacting performance. A research team from the School of Fashion and Textiles at The Hong Kong Polytechnic University (PolyU) has developed the iActive™ sportswear range which features a root-like liquid transport system and a skin-like active perspiration dissipater and utilises nature-inspired, anti-heat textile fabrics to expedite sweat removal, effectively reducing the weight and stickiness of activewear caused by sweat accumulation during exercise.   The human body has millions of sweat glands that are vital for regulating body temperature by dissipating sweat for evaporation to cool the skin’s surface. With unabating greenhouse gas emissions, the number of very hot days annually is expected to increase significantly. This will lead to elevated energy consumption and increased sweating during physical activity and outdoor labour. Even when wearing highly breathable clothes with good sweat-wicking properties, individuals may still experience discomfort due to excessive sweat accumulation.   A research team led by Dr SHOU Dahua, Limin Endowed Young Scholar in Advanced Textiles Technologies, Associate Professor of the School of Fashion and Textiles, and Member of the Research Centre of Textiles for Future Fashion at PolyU, has invented the groundbreaking iActive™, intelligent, electrically activated sportswear with a nature-inspired active perspiration function. This pioneering innovation has garnered significant recognition, including a Gold Medal at the 49th International Exhibition of Inventions Geneva this April.   Its nature-inspired technologies, including low-voltage-driven artificial “sweat glands” created by skin-like anti-heat textile fabrics and a root-like branching liquid transport system that aligns with the body’s sweat map, can actively and programmably transport sweat to a perspiration dissipater at the lower region of the sportswear, and quickly remove it as liquid droplets. The all-textile sweat dissipater is compact and operates at a safe output voltage of approximately 5-9V, and its battery is easy to detach from the clothing, making it convenient for users to repeatedly wash the clothing by hand or in a washing machine to maintain hygiene. When the human body’s sweat rate is low, iActive™ can still be used independently without the battery.   Based on the optimised wettability pattern and gradient, the research team utilises a skin-like textile fabric to transport sweat one-way quickly and dissipate it directionally from the inside to the outside. This feature reduces the stickiness and weight of clothing, improves breathability and ensures the garments remain dry and comfortable to wear. Experimental findings indicate that iActive™ creates a breathable and dry skin microclimate by dissipating sweat at a rate that is three times faster than the maximum human sweating rate. This innovation can also prevent discomfort from coldness and moisture after a workout. In comparison to traditional fabrics, the textile materials in iActive™ are 60% lighter and 50% less clingy when soaked, providing the wearer with all-round comfort and enabling sports enthusiasts and athletes to perform at their best.   Furthermore, a mobile app further aids personalised sweat management by wirelessly adjusting the sweat level of iActive™. This innovation is versatile and can be seamlessly integrated into a variety of textile materials to facilitate sustainable mass production. Beyond sportswear, iActive™ is also   well-suited to protective clothing and workwear for individuals engaged in prolonged, high-intensity physical labour and outdoor occupations, including healthcare professionals, construction workers, firefighters, law enforcement officers and others, thereby significantly enhancing their work performance.   Dr Shou Dahua stated, “The extreme weather and high temperatures resulting from global warming have elevated the importance of heatstroke prevention and cooling measures on a global scale. Drawing on the vivid phenomena of thermal insulation and directed liquid flow in nature, we aim to foster innovation and sustainable advancement in garment manufacturing by inventing intelligent clothing and materials to address global challenges. We seek to harness the power of technology to infuse fresh perspectives into the traditional clothing industry, thereby enhancing its competitiveness.”   His research team has also developed a premium fabric named Omni-Cool-Dry™, drawing inspiration from volcano dwelling beetles. This fabric not only provides ultra-fast sweat dissipation and ensures all-day comfort with its dry and breathable features under dynamic thermal conditions, but also reflects solar radiation and emits body heat into the cold universe, enabling passive cooling. The team is working hard to leverage the benefits of both inventions to further enhance the sweat-dissipating and cooling capability of iActive™ sportswear.   Dr Shou Dahua, a core member of the PolyU Research Institute for Intelligent Wearable Systems and the Research Centre of Textiles for Future Fashion, has recently been bestowed with the 2023 Distinguished Achievement Award by The Fiber Society for his outstanding contributions to the fields of personal thermal and moisture management, intelligent wearables and soft robotics. The accolade is presented annually to an individual researcher worldwide. He has also received international innovation awards, including consecutive TechConnect Global Innovation Awards in 2021 and 2022. Moreover, his research papers have been published in various internationally renowned academic journals including Science Advances, PNAS, Advanced Functional Materials, and Advanced Energy Materials. Dr Shou will be chairing The Fiber Society Spring 2025 Conference at PolyU.

Replicating Shear-mediated Self-assembly of Spider Silk Through Microfluidics

Dr Jianming Chen, Member of the Research Centre of Textiles for Future Fashion, collaborated with other researchers and published an article entitled “Replicating shear-mediated self-assembly of spider silk through microfluidics” in Nature Communications.   ABSTRACT The development of artificial spider silk with properties similar to native silk has been a challenging task in materials science. In this study, we use a microfluidic device to create continuous fibers based on recombinant MaSp2 spidroin. The strategy incorporates ion-induced liquid-liquid phase separation, pH-driven fibrillation, and shear-dependent induction of β-sheet formation. We find that a threshold shear stress of approximately 72 Pa is required for fiber formation, and that β-sheet formation is dependent on the presence of polyalanine blocks in the repetitive sequence. The MaSp2 fiber formed has a β-sheet content (29.2%) comparable to that of native dragline with a shear stress requirement of 111 Pa. Interestingly, the polyalanine blocks have limited influence on the occurrence of liquid-liquid phase separation and hierarchical structure. These results offer insights into the shear-induced crystallization and sequence-structure relationship of spider silk and have significant implications for the rational design of artificially spun fibers.   Read the full article in Nature Communications. URL: https://doi.org/10.1038/s41467-024-44733-1

Robust, Flexible, and Superhydrophobic Fabrics for High-efficiency and Ultrawide-Band Microwave Absorption

Prof. Xungai Wang, Member of the Research Centre of Textiles for Future Fashion, collaborated with other researchers and published an article entitled “Robust, Flexible, and Superhydrophobic Fabrics for High-efficiency and Ultrawide-Band Microwave Absorption” in Engineering.   ABSTRACT Microwave absorption (MA) materials are essential for protecting against harmful electromagnetic radiation. In this study, highly efficient and ultrawide-band microwave-absorbing fabrics with superhydrophobic surface features were developed using a facile dip-coating method involving in situ graphene oxide (GO) reduction, deposition of TiO2 nanoparticles, and subsequent coating of a mixture of polydimethylsiloxane (PDMS) and octadecylamine (ODA) on polyester fabrics. Owing to the presence of hierarchically structured surfaces and low-surface-energy materials, the resultant reduced graphene oxide (rGO)/TiO2-ODA/PDMS-coated fabrics demonstrate superhydrophobicity with a water contact angle of 159° and sliding angle of 5°. Under the synergistic effects of conduction loss, interface polarization loss, and surface roughness topography, the optimized fabrics show excellent microwave absorbing performances with a minimum reflection loss (RLmin) of −47.4 dB and a maximum effective absorption bandwidth (EABmax) of 7.7 GHz at a small rGO loading of 6.9 wt%. In addition, the rGO/TiO2-ODA/PDMS coating was robust, and the coated fabrics could withstand repeated washing, soiling, long-term ultraviolet irradiation, and chemical attacks without losing their superhydrophobicity and MA properties. Moreover, the coating imparts self-healing properties to the fabrics. This study provides a promising and effective route for the development of robust and flexible materials with microwave-absorbing properties.   Read the full article in Nature Communications. URL: https://doi.org/10.1016/j.eng.2024.03.009

RCTFF and People’s Government of Lanxi City Sign MoU to Establish Partnership

Research Centre of Textiles for Future Fashion (RCTFF) and the People’s Government of Lanxi City (Lanxi) signed a Memorandum of Understanding (MoU) on 24 Apr 2024, symbolising a closer and more concrete collaborative relationship. The two sides will collaborate to pursue joint research projects aimed at developing new technologies and materials, as well as to facilitate the exchange of knowledge.

Soft Robotic Textiles for Adaptive Personal Thermal Management

Prof. Jintu Fan, Director of the Research Centre of Textiles for Future Fashion (RCTFF), and Dr Dahua Shou, Member of RCTFF, collaborated with other researchers and published an article entitled “Soft Robotic Textiles for Adaptive Personal Thermal Management” in Advanced Science.   ABSTRACT Thermal protective textiles are crucial for safeguarding individuals, particularly firefighters and steelworkers, against extreme heat, and for preventing burn injuries. However, traditional firefighting gear suffers from statically fixed thermal insulation properties, potentially resulting in overheating and discomfort in moderate conditions, and insufficient protection in extreme fire events. Herein, an innovative soft robotic textile is developed for dynamically adaptive thermal management, providing superior personal protection and thermal comfort across a spectrum of environmental temperatures. This unique textile features a thermoplastic polyurethane (TPU)-sealed actuation system, embedded with a low boiling point fluid for reversible phase transition, resembling an endoskeleton that triggers an expansion within the textile matrix for enhanced air gap and thermal insulation. The thermal resistance improves automatically from 0.23 to 0.48 Km2 W−1 by self-actuating under intense heat, exceeding conventional textiles by maintaining over 10 °C cooler temperatures. Additionally, the knitted substrate incorporated into the soft actuators can substantially mitigate convective heat transfer, as evidenced by the thermal resistance tests and the temperature mapping derived from numerical simulations. Moreover, it boasts significantly increased moisture permeability. The thermoadaptation and breathability of this durable all-fabric system signify considerable progress in the development of protective clothing with high comfort for dynamic and extreme temperature conditions.   Read the full article in Advanced Science. URL: https://doi.org/10.1002/advs.202309605

RCTFF Secured Funding from the Innovation and Technology Fund

Dr Tracy Mok (Associate Director of RCTFF), Prof. Jintu Fan (Director of RCTFF), and Ir Prof. Albert Chan (Member of RCTFF), recently have secured approximately HK$5 million from the Innovation and Technology Fund (ITF) for a 2-year research project entitled “Multimode Anti-Heating Green Uniforms for Construction Workers in Hong Kong – A complete ESG development and Management Proposal”.   This project aims to develop new Multimode Anti-Heating green fabrics and garments for the production of construction worker uniforms in Hong Kong. The project will investigate new methods that best integrate novel knitting fabric structure as well as fabric surface modification approaches to realise new radiative cooling fabrics for construction worker uniforms. For moisture management, the new uniforms will allow fast and one-way moisture transportation from skin to outer surface of the garments. It can keep the skin dry and prevent the clothing layer sticking to the skin even in an excessive sweating condition. For thermal management, the garments can facilitate the dissipation of mid-infrared radiation from human body to the environment for passive cooling while the outer layer of the fabrics can reflect solar radiation in a broad spectrum (near-IR, visible, UV) to reduce the heat absorption in outdoor environment. New fabrics and uniforms will be developed, tested and evaluated so as to suggest new standard/guideline for the production and management of construction worker uniforms, ensuring compliance to the new quality requirements.

Personal Thermal Management by Radiative Cooling and Heating

Prof. Jintu Fan, Director of the Research Centre of Textiles for Future Fashion (RCTFF), Prof. Xungai Wang and Dr Dahua Shou, Members of RCTFF, collaborated with other researchers and published an article entitled “Personal Thermal Management by Radiative Cooling and Heating” in Nano-Micro Letters.   ABSTRACT Maintaining thermal comfort within the human body is crucial for optimal health and overall well-being. By merely broadening the set-point of indoor temperatures, we could significantly slash energy usage in building heating, ventilation, and air-conditioning systems. In recent years, there has been a surge in advancements in personal thermal management (PTM), aiming to regulate heat and moisture transfer within our immediate surroundings, clothing, and skin. The advent of PTM is driven by the rapid development in nano/micro-materials and energy science and engineering. An emerging research area in PTM is personal radiative thermal management (PRTM), which demonstrates immense potential with its high radiative heat transfer efficiency and ease of regulation. However, it is less taken into account in traditional textiles, and there currently lies a gap in our knowledge and understanding of PRTM. In this review, we aim to present a thorough analysis of advanced textile materials and technologies for PRTM. Specifically, we will introduce and discuss the underlying radiation heat transfer mechanisms, fabrication methods of textiles, and various indoor/outdoor applications in light of their different regulation functionalities, including radiative cooling, radiative heating, and dual-mode thermoregulation. Furthermore, we will shine a light on the current hurdles, propose potential strategies, and delve into future technology trends for PRTM with an emphasis on functionalities and applications.   Read the full article in Nano-Micro Letters. URL: https://doi.org/10.1007/s40820-024-01360-1

A Durable, Breathable, and Weather-Adaptive Coating Driven by Particle Self-Assembly for Radiative Cooling and Energy Harvesting

Dr Dahua Shou, Member of the Research Centre of Textiles for Future Fashion, collaborated with other researchers and published an article entitled “A Durable, Breathable, and Weather-Adaptive Coating Driven by Particle Self-Assembly for Radiative Cooling and Energy Harvesting” in Nano Energy.   ABSTRACT The imperative to attain net-zero emissions emphasizes energy conservation. Radiative cooling stands out as a compelling technology in this pursuit for its self-sufficiency and cost-effectiveness. However, the radiative cooling faces the challenge in varied weather, including high ultraviolet (UV), cloudy and rainy days, primarily due to instability of radiative cooling materials and mono-energy conservation mechanism. To address this, a durable, breathable, and weather-adaptive coating (porous PTFE coating) is developed through assembling polyfluortetraethylene (PTFE) nanoparticles enabled by the differential interaction in a binary-solvent system. The porous PTFE coating exhibits high solar reflectivity (94%) and thermal emissivity (93%), which results from the precisely tunable assembly of PTFE nanoparticles, forming a desired porous morphology. This serves as effective scattering, achieving a sub-ambient cooling effect of approximately 5 ℃ at midday. With an outstanding UV protection factor (UPF) of 179.15, the porous PTFE coating sustained stability after 40 days exposure to solar radiation. Leveraging the porous PTFE coating's exceptional negative triboelectric effect, an engineered high-performance droplet electricity nanogenerator (DEG) achieves a notable power density of 153.8mW/m2, revealing significant potential for raindrop energy harvesting on rainy days. The versatile porous PTFE coating, with its exceptional weather adaptation and UV stability, holds promise for diverse applications, advancing sustainable and efficient energy solutions with reliability in varying conditions.   Read the full article in Nano Energy. URL: https://doi.org/10.1016/j.nanoen.2024.109489

Shenzhou International Group Holdings Limited visited The Hong Kong Polytechnic University

Mr Jian-Rong Ma, Chairman of the Board and Executive Director, along with a delegation from Shenzhou International Group Holdings Limited (Shenzhou), visited The Hong Kong Polytechnic University (PolyU) on February 2nd. Shenzhou is the largest vertically-integrated knitwear manufacturer in China. Its primary production base is situated in the Ningbo Economic and Technological Development Zone. The delegation was warmly received by Prof. Jintu Fan, Director of the Research Centre of Textiles for Future Fashion (RCTFF), and his research team. Prof. Fan and his team presented their research work on Breathable Fabrics and a mockup of their Fashion Style Recommendation System. Meanwhile, Mr Ma shared his views on the Fashion and Textile Industry. Both sides anticipated ongoing, comprehensive collaboration in the future. The delegation also had the opportunity to meet with Prof. Jin-Guang Teng, President of PolyU. Prof. Teng presented Mr Ma with a certificate, appointing him as a member of the International Advisory Committee of RCTFF. The visit provided a platform for potential collaborations between Shenzhou and PolyU.

3D Cellular Solar Crystallizer for Stable and Ultra-Efficient High-Salinity Wastewater Treatment

Prof. Jintu Fan, Director of the Research Centre of Textiles for Future Fashion (RCTFF), and Dr Zhanxiao Kang, Member of RCTFF, collaborated with other researchers and published an article entitled “3D Cellular Solar Crystallizer for Stable and Ultra-Efficient High-Salinity Wastewater Treatment” in Advanced Science.   ABSTRACT Recent developed interfacial solar brine crystallizers, which employ solar-driven water evaporation for salts crystallization from the near-saturation brine to achieve zero liquid discharge (ZLD) brine treatment, are promising due to their excellent energy efficiency and sustainability. However, most existing interfacial solar crystallizers are only tested using NaCl solution and failed to maintain high evaporation capability when treating real seawater due to the scaling problem caused by the crystallization of high-valent cations.   Herein, an artificial tree solar crystallizer (ATSC) with a multi-branched and interconnected open-cell cellular structure that significantly increased evaporation surface is rationally designed, achieving an ultra-high evaporation rate (2.30 kg m−2 h−1 during 2 h exposure) and high energy efficiency (128%) in concentrated real seawater. The unit cell design of ATSC promoted salt crystallization on the outer frame rather than the inner voids, ensuring that salt crystallization does not affect the continuous transport of brine through the pores inside the unit cell, thus ATSC can maintain a stable evaporation rate of 1.94 kg m−2 h−1 on average in concentrated seawater for 80 h continuous exposure. The design concept of ATSC represents a major step forward toward ZLD treatment of high-salinity brine in many industrial processes is believed.   Read the full article in Advanced Science. URL: http://doi.org/10.1002/advs.202305313