Hong Hu

• PhD
• Professor at The Hong Kong Polytechnic University

Energy‐absorbing auxetic composites show flexibility in usage, yet they remain non‐biodegradable, thus creating environmental challenges. Implementing sustainable auxetic materials constructed from natural fibers and biodegradable polymers remains essential for lowering environmental effects. This research involves the fabrication of eco‐friendly a...

Carbon fiber reinforced polymer (CFRP) auxetic composite structures have attracted an increasing attention in recent years due to their lightweight and superior mechanical properties compared with traditional auxetic structures. However, most of the reported all‐CFRP auxetic structures are often accompanied with cliff‐like stress drops during the f...

Multifunctional acoustic and mechanical metamaterials prepared from continuous CFRP composites Multifunctional metamaterials combining acoustic and mechanical advantages were created from continuous carbon fiber composites, offering lightweight, high-strength, robust, and effective low-frequency noise reduction capabilities. Image designed by SciFi...

Polylactic acid (PLA) fiber, renowned for its renewable and biodegradable nature, is increasingly recognized as a promising alternative to conventional polyethylene terephthalate (PET) polyester fiber in the textile industry. However, the poor dyeability of PLA has limited its widespread industrial application. This study aims to enhance the dyeabi...

Numerical modeling of textile structures at the yarn level is challenging, yet provides information not obtainable through experimental studies alone. This study is focused on the development and finite-element analysis (FEA) of a three-dimensional (3D) woven structure with an in-plane negative Poisson’s ratio (NPR) effect, with the aim of explorin...

The imperative advance towards achieving “carbon neutrality” necessitates the development of porous structures possessing dual acoustic and mechanical properties in order to mitigate energy consumption.

Wearable electronic textiles (e‐textiles) are transforming personalized healthcare through innovative applications. However, integrating electronics into textiles for e‐textile manufacturing exacerbates the rapidly growing issues of electronic waste (e‐waste) and textile recycling due to the complicated recycling and disposal processes needed for m...

This paper reports a study on the comfort properties of poly(lactic acid) (PLA)/cotton multilayered quilted fabrics. Fifteen multilayered quilted fabrics with diverse structural parameters were first fabricated using three different linear densities of PLA filaments as inlaid yarns and five distinct blending ratios of PLA/cotton blended yarns as su...

A novel type of petal-like structure that exhibits superior mechanical properties, was proposed and fabricated by integrating advantages of metamaterial, multi-stage deformation, and high strength of fiber-reinforced composites. Compression testing and finite element analysis were first conducted on three petal-like structures formed with different...

In this paper, low‐velocity impact properties and impact damage responses of a novel type of 3D hybrid auxetic structures made from carbon fiber‐reinforced polymer (CFRP) laminates were investigated experimentally and numerically. The structures were first fabricated with three different rib's width ratios t 1 / t 0 , and then impacted with three d...

Textile-based wearable electronics have attracted intensive research interest due to their excellent flexibility and breathability inherent in the unique three-dimensional porous structures. However, one of the challenges lies in achieving highly conductive patterns with high precision and robustness without sacrificing the wearing comfort. Herein,...

Bamboo and its hybrid composites were made using the hand lay-up method to evaluate the change in mechanical and physical properties that occurred through filler addition. Density measurements and tensile test results showed an increment in values when a certain percentage of silicon carbide (SiC) was added. As the SiC percentage grows from 0 to 6...

Fiber‐shaped conductors with high electrical conductivity, stretchability, and durability have attracted increasing attention due to their potential for integration into arbitrary wearable forms. However, these fiber conductors still suffer from low reliability and short life span, particularly in harsh environments. Herein, a conductive, environme...

Three-dimensional spacer fabric is a type of one-piece sandwich structure consisting of two outer layers and vertical and inclined spacer monofilaments. It behaves like a cushioning material, having linear, plateau, and densification stages under compression. This article elucidates the compression mechanism of a typical spacer fabric in terms of g...

This paper reports the low‐velocity impact performance of 3D auxetic composite embedded with re‐entrant triangle inclusions by both experiments and finite element (FE) simulations. Both auxetic and non‐auxetic samples were manufactured by embedding inclusions made from carbon fiber/epoxy laminates into silicone rubber matrix. The pure silicone rubb...

The auxetic property of macro-porous rotating square structure has been investigated by many using either experimental or numerical approaches. Given the low breaking strength of the typical rotating square structure, it was proposed to employ an elastic base material to the cellular auxetic structure to improve its strength while maintaining its a...

For dry adhesive-based operation, highly adaptable and stable manipulation is important but also challenging, especially for irregular objects with complex surface (such as abrupt profile and acute projection) under vibration-inducing environments. Here, a multi-scale adhesive structure, with mechanically isolated energy-absorbing backing, based on...

Artificial dry adhesives have exhibited great potential in the field of robotics. However, there is still a wide gap between bioinspired adhesives and living tissues, especially regarding the surface adaptability and switching ability of attachment/detachment. Here, we propose a sensing-triggered stiffness-tunable smart adhesive material, combining...

Auxetic textiles are emerging as an enticing option for many advanced applications due to their unique deformation behavior under tensile loading. This study reports the geometrical analysis of three-dimensional (3D) auxetic woven structures based on semi-empirical equations. The 3D woven fabric was developed with a special geometrical arrangement...

The ability to tolerate large strains during various degrees of deformation is a core issue in the development of flexible electronics. Commonly used strategies nowadays to enhance the strain tolerance of thin film devices focus on the optimization of the device architecture and the increase of bonding at the materials interface. In this paper, we...

Stretch woven fabrics are known for their elastic and recovery properties. To date, they found many interesting applications from simple jeans to complex fabric structures with functional properties for example bi-stretch auxetic woven fabrics, compressions garments and stretchable textile carriers for healthcare applications. Many studies have bee...

Intrinsically stretchable organic photovoltaic (is-OPV) with high efficiency and transparency remains a grand challenge for wearable applications. Herein, we report a full-solution processed device framework for semi-transparent is-OPV. A ferroconcrete-liked...

Highly conductive, durable, and breathable metal-coated textiles are critical building block materials for future wearable electronics. In order to enhance the metal adhesion on the textile surface, existing solution-based approaches to preparing these materials require time-consuming presynthesis and/or premodification processes, typically in the...

Textile‐based triboelectric nanogenerators (t‐TENGs) possess the unique wearability characteristics of fabrics. The advent of t‐TENGs not only broadens the development direction of new materials in the textile industry but also endows TENGs with greater application potential. However, the electrical output and desired comfort properties of t‐TENGs...

Industrial wearable electronic devices critically require the seamless integration of flexible lithium-ion batteries (LIBs) without compromising high energy density and long cycling stability. Textile-based LIBs show excellent mechanical flexibility but sacrifice energy density and cycling stability. Inspired by the rigid-soft segment structure of...

Nanocellulose is the most abundant material extracted from plants, animals, and bacteria. Nanocellulose is a cellulosic material with nano-scale dimensions and exists in the form of cellulose nanocrystals (CNC), bacterial nanocellulose (BNC), and nano-fibrillated cellulose (NFC). Owing to its high surface area, non-toxic nature, good mechanical pro...

The contact splitting hypothesis (CSH) has been proposed for around 20 years, which suggests that the patterned or fibrillar surfaces enable very efficient biological attachment systems (e.g., Geckos’ seta). However, there is still a debate in academic community on the necessity of the CSH in man-made adhesives, since experiments have indicated tha...

Life‐changing illnesses and fatalities caused by inefficient personal protective clothing and equipment are increasing day by day. The discrepancy between the test standards, environmental conditions, and infield collision is the reason why personal protection equipment and clothing have not yet decreased the number of injuries in various fields su...

Lithium (Li) metal anode offers a promising solution for high-energy-density lithium metal batteries (LMBs). However, the significant volume expansion of Li metal during charge results in poor cycling stability as a result of the dendritic deposition and broken solid electrolyte interphase. Herein, we propose a facile one-step roll-to-roll fabricat...

Different auxetic structures and auxetic phenomena are continuously explored by researchers in the field of textiles with enhanced properties for broader application areas. However, developing three-dimensional (3D) auxetic structures by using weaving technology is a real challenge compared to knitting and non-weaving techniques. This research work...

Inkjet‐printed metal electrodes with desirable morphologies and electrical properties are indispensable cornerstones for printable and flexible electronics. However, methods to fabricate metal electrodes nowadays mostly request the sintering of printed metal particles, which not only will easily damage heat‐sensitive plastic substrates, but also is...

Sustainable poly(lactic acid) multifilaments are a new type of biodegradable fibers that have gained increasing attention in textile product development. However, low moisture management performance has hindered their application in high added-value textile products such as functional garments and sportswear. In this work, profiled poly(lactic acid...

Unlimited growth of lithium dendrites is undesirable yet preventing this still remains a challenge for pursuing high‐energy battery systems. Serious safety hazards caused by short circuit and fire demand accurate control of the nucleation location of lithium deposition. Here, an inverted anode structure enabled by simple flipping of carbon fabric a...

Dip‐pen nanolithography (DPN) can directly write a variety of materials on the substrates at the sub‐50 nm to micrometer length scale. While this tool has been extensively exploited to construct functional nanostructures and address important scientific questions, extending the capability from low‐dimensional molecular patterning to direct additive...

The development of high-performance apparels is gaining pace these days because consumers are expecting products with better quality and extra functions. And the high-performance garments are generally of higher added values, which is most attractive to the apparel companies. As one of the major fabric manufacturing techniques, warp knitting posses...

Composites with negative Poisson's Ratio (NPR), also known as auxetic composites, are of great interests due to excellent properties. Auxetic composites of various types have been developed, however most of them have anisotropic NPR behaviour. This paper reports a new type of three-dimensional (3D) composites with nearly isotropic NPR by randomly e...

Increasing the electrode thickness of energy‐storage devices can enhance the areal capacitance, but often results in a significant decrease in the volumetric capacitance. This tradeoff between the volumetric capacitance and electrode thickness, which is ascribed to the poor ion and charge transport in thick electrodes, has been a major obstacle to...

Three-dimensional (3D) fabrics with negative Poisson’s ratio (NPR) are known as 3D auxetic fabrics. They expand (or contract) in the direction perpendicular to stretch (or compression) under uniaxial tensile (or compressing) conditions. Many enhanced properties come with this unusual auxetic behaviour, such as shear modulus, indentation resistance,...

Bioinspired structural adhesives that are capable of bonding two objects together have recently found widespread applications in industrial fields, because of their promising reusability and environmental friendliness. However, such adhesives are usually monofunctional and cannot yield real‐time detection on the adhesion status, which is important...

The ever‐increasing development of flexible and wearable electronics has imposed unprecedented demand on flexible batteries of high energy density and excellent mechanical stability. Rechargeable lithium (Li) metal battery shows great advantages in terms of its high theoretical energy density. However, the use of Li metal anode for flexible batteri...

This paper aims to identify the underlying physical mechanism for the compression deformation of a warp-knitted spacer fabric with a typical structure with experimental and theoretical studies. Compression tests were carried out to measure the load–displacement relationship of the fabric. The structural features of the spacer yarns were photographe...

High‐capacity and omnidirectionally flexible wire‐type lithium (Li)–metal batteries represent a feasible technology for the realization of electronic textiles. However, the use of commercially available Li–metal wires as anodes nowadays confronts many electrochemical and mechanical issues such as dendrite formation, low yield strength, and poor fat...

Because of the large abundance of sodium (Na) as a source material and the easy fabrication of Na-containing compounds, the sodium (Na) battery is a more environmentally friendly and sustainable technology than the lithium-ion battery (LIB). Na-metal batteries (SMBs) are considered promising to realize a high energy density to overtake the cost eff...

Liquid metal (LM) has recently been used as an advanced stretchable material for constructing stretchable and wearable electronics. However, due to the poor wettability of LM and the large dimensional change during stretching, it remains very challenging to obtain a high conductivity with minimum resistance increase over large tensile strains. To a...

Understanding the adhesion between rough surfaces has practical significance. We derive a simple analytical formula on the basis of the classic order statistics to predict the interfacial binding energy between rough surfaces. It is found that the strong length scale dependence of adhesion ranging from the nominal size scale down to any artificiall...

Developing biotemplating techniques to translate microorganisms and cultured mammalian cells into metallic biocomposites is of great interest for biosensors, electronics, and energy. The metallization of viruses and microbial cells is successfully demonstrated via a genetic engineering strategy or electroless deposition. However, it is difficult to...

This paper investigates the energy harvesting (EH) performance of a nonlinear dielectric elastomer pendulum (DEP) under the random narrowband excitation. The DEP that can convert the vibration energy into electrical energy consists of a dielectric elastomer membrane with a mass, which is similar to a spring pendulum. A dynamic analysis model of the...

This paper reports a geometrical analysis of auxetic woven fabrics based on foldable geometry. Two fabrics having different geometrical parameters were first designed and fabricated and then subjected to tensile tests in two principal directions. Based on the experimental observations of the geometry of one fabric structural unit cell at different...

Auxetic fabrics are those with negative Poisson’s ratio and have received increasing attention in recent years. In our previous study, a series of auxetic warp knitted fabrics were developed based on reentrant geometry and their auxetic effects were experimentally investigated. Unlike weft knitted fabrics, the preparation and production process of...

Sunlight can be converted to electricity via solar cells, with which then light can be generated the other way around. In this regard, skyscrapers performing light show during night or the bright Karst landscape under the ground are exemplified, echoing the geometry of the TiO2 nanopillars which are fabricated via a low‐temperature dry process and...

Poly(lactic acid) (PLA) fiber was developed more than a decade ago. It has been regarded as the most promising sustainable and biodegradable fiber to replace conventional polyethylene terephthalate (PET) polyester fiber in textile products. This paper reviews recent developments in PLA polymerization, PLA filament and fiber spinning, staple yarn sp...

Auxetic woven fabrics made with special geometrical structures have gained the interest of textile scientists in recent years. This paper reports a study on auxetic woven fabric based on a double-directional parallel in-phase zig-zag foldable geometrical structure. Such a fabric has been already produced and investigated for its negative Poisson's...

This chapter introduces the definition of Poisson's ratio and briefly discusses the role of different structures and geometries (re‐entrant, rotating geometry, nodule based, chiral‐based, foldable) for achieving negative Poisson's ratio. Different types of auxetic polymer fibers and materials are briefly introduced. The potential applications of au...

This chapter aims to describe woven fabric mechanics and factors in relation to the constituent yarns and fabric structure, which may affect the ultimate mechanical properties of woven fabrics. Factors including weave, crimp, weave factor, and structural geometry are discussed. In order to develop a better understanding of woven fabric mechanics, d...

Auxetic fabrics made of nonauxetic yarns have gained increasing interest of textile scientists. Most recently, single‐layered bistretch auxetic woven fabrics made of nonauxetic yarns based on parallel in‐phase zigzag foldable geometry have been reported to have auxetic behavior when stretched along both principal directions. It is also reported tha...

The folded geometry has successfully been transformed into auxetic woven fabric in the literature. However, the influences of the micro‐geometric parameters on the macroscopic behavior have not been addressed yet. In this paper, several key micro‐geometric parameters for the folded geometry were identified and the mechanical behaviors of the folded...

Auxetic braided structures

Auxetic Braided Structures

Auxetic woven fabrics made of non-auxetic yarns have gained the interest of textile scientists in recent times. Such fabrics have already been produced and investigated for their negative Poisson's ratio (NPR) effect in two principle directions. However, the NPR effect of these fabrics in different biased tensile directions has not been studied. In...

This paper reports a novel method to fabricate auxetic warp knitted fabrics on a tricot warp knitting machine based on a special structure design and knitting process. Three auxetic warp knitted structures were successfully developed and all of them were designed to form a reentrant hexagonal geometry to acquire an auxetic effect. To provide the fa...

Auxetic woven fabrics made of non-auxetic yarns have gained an interest in textile scientists in recent times. This paper is aimed to report the negative Poisson’s ratio (NPR) effect of auxetic woven fabric based on foldable geometry in different tensile directions and the influence of repeating tensile tests on the NPR effect retention ability of...

This paper reports a study on the geometrical analysis of bi-stretch auxetic woven fabric based on a re-entrant hexagonal geometry. The fabric was first designed and fabricated. Then, the fabric was subjected to tensile tests, and changes in the geometry of the fabric structural unit cell at different tensile strains were observed when stretched ei...

This paper reports a new type of auxetic yarn made with circular braiding technology to overcome the yarn slippage problem in the conventional helical auxetic yarn structure. Various auxetic yarn structures are firstly produced on a vertical circular braiding machine with 16 yarn carries by changing the number and arrangement of stiff yarn as well...

Auxetic plied yarn is a novel type of yarn structure formed with two types of component yarns with different moduli. Although the effect of structural parameters on its negative Poisson's ratio behavior has been investigated by both experimental and geometrical analyses, the influence of material properties, including yarn tensile modulus and frict...

The auxetic material is a special kind of materials that possess negative Poisson’s ratio (NPR), where the materials laterally expand when stretched and shrink when compressed. Auxetic textiles have been developed in the recent years including many areas that are yarn, fabrics, braids, non-woven and composites. However, the use of conventional yarn...

The fabrication of auxetic fabrics by using conventional yarns and machinery has gained extraordinary interest from researchers in recent years. However, to date this approach has only been adopted to fabricate auxetic knitted fabrics and uni-stretch auxetic woven fabrics. This paper reports a study that aimed to develop a new class of bi-stretch w...

Inspired by the sophisticated artificial leather garment industry and toward enhancing wearability of energy storage devices, we demonstrate a polyurethane artificial leather supercapacitor with large sheet electrodes embedded in the leather layer simultaneously working as a polyelectrolyte. This design totally reserves textiles underneath and thus...

Powering flexible electronics by wearable energy‐storage or energy‐harvesting devices has attracted enormous research interest recently. However, the continual powering offered by individual energy‐storage devices, such as rechargeable batteries or supercapacitors, becomes problematic once the energy stored is fully discharged. Therefore, the integ...

This paper presents a theoretical analysis of the auxetic plied yarn (APY) structure formed with two types of single yarns having different diameter and modulus. A model which can be used to predict its deformation behavior under axial extension is developed based on the theoretical analysis. The developed model is first compared with the experimen...

This paper reports a finite element (FE) analysis of three-dimensional (3D) auxetic textile composite by using commercial software ANSYS 15 under compression. The two-dimensional (2D) FE model was first developed and validated by experiment. Then, the validated model was used to evaluate effects of structural parameters and constituent material pro...

3D auxetic textile composite is a special type of auxetic materials which has attracted more attention in recent years. Its deformation behaviour and mechanical properties under quasi-static compression have been investigated in the previous studies. In this paper, a further study on its mechanical properties under low-velocity impact is presented....

For the first time, a hierarchical phosphor Y2O3:Eu³⁺/MCM-41/YVO4:Eu³⁺, with a core–shell-core heterostructure, is presented in this study. Synergistically bridging the phosphors Y2O3:Eu³⁺ (as an inner core) and YVO4:Eu³⁺ (as an outer core) by amorphous SiO2, i.e., MCM-41 (with ordered mesoporous channels) leads to the generation of the core–shell-...

Fiber-shaped supercapacitors have attracted widely attention for their great potential application in future portable and wearable electronics compared with traditional 2D planar structured supercapacitors, which is associated to their high flexibility, tiny volume and good deformability. Asymmetric designed supercapacitors usually couple two diffe...

With intrinsic safety and much higher energy densities than supercapacitors, rechargeable nickel/cobalt-zinc-based textile batteries are promising power sources for next generation personalized wearable electronics. However, high-performance wearable nickel/cobalt-zinc-based batteries are rarely reported because industrially weavable and knittable...

The multilayer orthogonal auxetic composites have been previously developed and tested to prove that they own excellent energy absorption and impact protection characteristics in a specific strain range under low-velocity impact. In this study, a three dimensional finite element (FE) model in ANSYS LS-DYNA was established to simulate the mechanical...

This paper presents an experimental study of tensile and deformation behavior of an auxetic plied yarn structure. The basic configuration of the plied structure formed with two soft yarns and two stiff yarns was firstly introduced. Based on this 4-ply helix structure, six kinds of yarn samples were made by different combinations of soft yarns, stif...

An ideal absorbent dressing requires high absorbency, moisture retaining and antimirobial properties. In this study, the application of silver-containing spacer fabric as an antimicrobial wound dressing was investigated. The silver distribution on spacer fabric was different from layer-by-layered fabric. The middle layer of spacer fabric contained...

Fabrics with zero or negative Poisson’s ratio are referred as auxetic fabrics, which have the unusual property of lateral expansion or zero expansion upon stretch. The use of conventional materials and machinery to produce auxetic fabrics has gained the interest of researchers in recent years. However, this approach is limited to knitted fabrics on...

Recently, asymmetric supercapacitors (ASCs) have attracted extensive research interest worldwide for their potential application in emerging energy-related fields. The smart integration of high overall cell operating voltage and large capacitance can be realized in all-pseudocapacitive-electrode-materials-based ASCs. This innovative all-pseudocapac...