Thermoplastic Polyurethane Matrix Research Articles

Morphological Electrical and Hardness Characterization of Carbon Nanotube-Reinforced Thermoplastic Polyurethane (TPU) Nanocomposite Plates.

The impacts on the morphological, electrical and hardness properties of thermoplastic polyurethane (TPU) plates using multi-walled carbon nanotubes (MWCNTs) as reinforcing fillers have been investigated, using MWCNT loadings between 1 and 7 wt%. Plates of the TPU/MWCNT nanocomposites were fabricated by compression molding from extruded pellets. An X-ray diffraction analysis showed that the incorporation of MWCNTs into the TPU polymer matrix increases the ordered range of the soft and hard segments. SEM images revealed that the fabrication route used here helped to obtain TPU/MWCNT nanocomposites with a uniform dispersion of the nanotubes inside the TPU matrix and promoted the creation of a conductive network that favors the electronic conduction of the composite. The potential of the impedance spectroscopy technique has been used to determine that the TPU/MWCNT plates exhibited two conduction mechanisms, percolation and tunneling conduction of electrons, and their conductivity values increase as the MWCNT loading increases. Finally, although the fabrication route induced a hardness reduction with respect to the pure TPU, the addition of MWCNT increased the Shore A hardness behavior of the TPU plates.

Experimental investigation of electrolytically treated and silane grafted carbon fiber-reinforced thermoplastic polyurethane composites

In this study, the continuous fiber rowing of 12K carbon was electrolytically oxidized by incorporating three different types of electrolytes: Ammonium bicarbonate, Sulfuric acid, and Sodium hydroxide at various concentrations. Upon chemical treatment, the fibers were grafted with 3-Aminopropyl-triethoxysilane (APTS), a silane coupling agent, to achieve better interlocking and compatibility with the thermoplastic polyurethane (TPU) matrix. Mechanical properties were analyzed by tensile tests, morphological analysis was carried out through Scanning Electron Microscopy, and spectral analysis was studied through X-ray photoelectron spectroscopy (XPS) characterizations. The results show that 10% sulfuric acid treatment plus APTS grafted carbon fiber/TPU composites showed an average tensile load capacity of 2528 N, about 39% higher than raw carbon/TPU. The morphological analysis provided compelling evidence for the increase in mechanical properties of modified fiber composites as the interfacial bonding between the electrolytically modified and silane coated fiber/TPU composites was much better than the raw fiber/TPU composites. Further, XPS results confirm that the atomic percentages of Carbon have been reduced, whereas the percentage of oxygen and nitrogen have increased. These compositional changes indicate that the overall interaction between the fiber and the matrix has been enhanced, accounting for improved compatibility between the two interacting phases.

Engineering of Interfacial Interactions Among BN And CNT Hybrid Towards Higher Heat Conduction Within TPU Composites

The demand for high thermal conductivity has stimulated the rapid development of materials that can efficiently manipulate thermal energy for future applications. Typically, polymer-based composites on hexagonal boron nitride (h-BN) are excellent for providing thermally conductive yet electrically insulating pathways. However, it is quite difficult for BN alone to develop strong interfacial connections within polymer chains. In this work, first, we established the hydroxylation of both h-BN and carbon nanotubes (CNT) then formed a urethane crosslink between the filler-filler interfaces and thermoplastic polyurethane (TPU) matrix. Owing to the unique structure of hybrid fillers, an unprecedented thermal conductivity of 4.52 Wm-1K-1 is achieved at just 60 wt. % loading of h-BN and 2 wt. % of CNT. Nevertheless, outstanding yielding strength and Young’s modulus such as 11.5 MPs and 13.5 GPa are also achieved by tension. We hope these findings will facilitate the researchers to design novel hybrid structures for next-generation electronic packaging.

Synergetic Effect of α-ZrP Nanosheets and Nitrogen-Based Flame Retardants on Thermoplastic Polyurethane

A supramolecular self-assembly method was used to prepare melamine cyanurate/α-ZrP nanosheets (MCA@α-ZrP) as a novel hybrid flame retardant for thermoplastic polyurethane (TPU). Microstructure characterization showed a uniform dispersion with strong interfacial strength of the MCA@α-ZrP hybrid within the TPU matrix, leading to simultaneous enhancements in both mechanical and fire-safety properties. The TPU/MCA@α-ZrP nanocomposite exhibited 43.1 and 47.0% increments in tensile strength and fracture energy, respectively. Thanks to the platelike structure of α-ZrP coupled with the dilution effect of MCA (releasing nonflammable gases), the hybrid MCA@α-ZrP reduced the peak heat release rate of TPU by 49.7% in comparison with 15.8 and 35.4% for TPU/MCA and TPU/ α-ZrP composites, respectively. The fire performance index of TPU is significantly promoted by 90% upon adding the MCA@α-ZrP hybrid. Additionally, LOI and UL-94 tests showed high flame-retarding characteristics for the MCA@α-ZrP hybrid. For example, LOI increased from 20.0% for neat TPU to 25.5% for the MCA@α-ZrP hybrid system, and it was rated V-1 from the UL-94 test. Furthermore, the smoke production and pyrolysis products were significantly suppressed by adding the MCA@α-ZrP hybrid into TPU. Interfacial hydrogen bonding, the dilution effect of MCA, forming a "labyrinth" layer, and catalytic action of α-ZrP nanosheets synergistically improved both the mechanical performance and flame retardancy of TPU nanocomposites. This work provides a new example of integrating traditional flame retardants with functional nanosheets to develop polymeric nanocomposites with high mechanical and fire-safety properties.

Compatibilization of coir fiber and elastomeric polyurethane by green modification routes

Tuning the chemical functionality of lignocellulosic fiber plays a key role in the development of mechanically strong composites to overcome the lack of compatibility between composite phases, which is a major challenge in multidimensional applications of eco-composites. Herein, coir fiber (CF) surfaces were enriched through four kinds of modification routes – namely, mercerization, amino-functional silane treatment, bio-based epoxy resin sizing and isocyanate treatment – to enhance their interfacial adhesion to a thermoplastic polyurethane (TPU) matrix. The tensile strength and Shore hardness parameters of composites were improved by surface-modified CF inclusions. The thermomechanical response of TPU was optimized after CF loadings regardless of treatment type. The composite with silane-modified CF exhibited the lowest water uptake due to the hydrophobic behavior of the silane layer. The increase in interfacial interaction between the TPU matrix and modified CF was confirmed by scanning electron microscopy investigations. The chemically enriched surface of CF improves the performance of composites, thanks to improved adhesion in the TPU–CF interface.

Super-Stretchable Hybrid Aerogels by Self-Templating Strategy for Cross-Media Thermal Management.

Personal thermal management (PTM) materials have attracted increasing attention owing to their application for personal comfort in an energy-saving mode. However, they normally work in the same media such as in the air, and little is known about what will happen in other media like water. In this study, a system for cross-media thermal management (CMTM): passive cooling in air and thermal insulation underwater is proposed. Hybrid aerogels comprising thermoplastic polyurethane (TPU) matrix and superhydrophobic silica aerogel particle (SSAP) for CMTM are designed and synthesized using a thermally induced phase separation and self-templating strategy. The TPU matrix endows the aerogels with super stretchability (500%), shape memory, and outstanding healing recovery rate (89.9%), which are ideal characteristics for potential wearable usage. Additionally, the TPU and SSAP endow the aerogel with high solar reflectivity and infrared emissivity, thus achieving a sub-ambient cooling of 10.6°C in air. Moreover, the SSAP endows the aerogels with low thermal conductivity (0.052 W m-1 ·K-1 ) and high hydrophobicity (143°), enabling the aerogels for underwater thermal insulation. The CMTM performance of the aerogels makes them for potential uses in cross-media environments such as reefs and islands where cooling in air and thermal insulation in water are required.

Effects of infill orientation and percentage on the magnetoactive properties of 3D printed magnetic elastomer structures

This work investigates how the internal meso structure of fused filament fabrication parts influence the magnetoactive properties of printed magnetic elastomer structures. Elastomers were made by adding 40wt% magnetite (Fe3O4) to a thermoplastic polyurethane (TPU) matrix. Magnetoactive testing was used to investigate how varying the infill structure affected the mechanical response of the structures within an applied magnetic field. Different infill percentages (40%, 60%, and 100%) and infill orientations (0, 45, and 90 degrees) were tested to account for different mechanical stiffnesses and internal geometries. Each sample was magnetoactively tested with three transverse magnetic field orientations (front, back and top). The samples were placed between two electromagnets, and the angle of deflection was recorded as a function of applied field. The maximum angles of deflection for the testing setup were reached when using lower infill percentages and having infill oriented parallel to the long axis of the sample and transverse to the magnetic field. Transverse fields applied parallel to the print plane (front/back sample orientations) demonstrated the most magnetoaction due to easier alignment of the long side of the sample with the field. This coupled with the 0-degree infill orientation having less crosslinking constraining the bending stiffness led to greater deflection. The magnetic anisotropy of the infill structure likely also contributed to the large response from certain samples. It was concluded that for this fixed base material, it is more important to 3D print structures with lower stiffnesses than more net magnetic particulate (more infill) to achieve the most magnetoaction.

Mechanical Reinforcement of Thermoplastic Polyurethane Nanocomposites by Surface‐Modified Nanocellulose

AbstractUtilization of biodegradable nanofillers is an emerging approach for the sustainable development of polymer composites. Among numerous green nanofillers, nanocellulose has garnered significant attention because of its abundance, high mechanical strength, and reinforcing capability. However, the intrinsic hydrophilicity of nanocellulose often restricts its homogeneous dispersion in the hydrophobic polymer matrix, resulting in a poor reinforcement effect. In this study, a simple surface modification of cellulose nanofibrils (CNFs) using small hydrophobic molecules is presented. Hydrophobic‐modified CNFs have better solubility in organic solvents and exhibit homogeneous dispersion in a thermoplastic polyurethane (TPU) matrix. The molecular interaction between CNFs and the hard/soft segments (HS/SS) of TPU induces surface‐mediated crystallization with improved microphase separation of SS and HS. By bridging multiple HS and SS microdomains, hydrophobic‐modified CNFs improve the tensile modulus and ultimate tensile strength of the polymer nanocomposites. On the other hand, unmodified CNFs are strongly aggregated in the TPU matrix, which restricts the mechanical reinforcement. These results demonstrate that surface modification of nanocelluloses can engineer their dispersion state and interfacial interaction with matrix polymers, which are crucial for the mechanical reinforcement of polymer nanocomposites.

Improvement of the Thermal Conductivity and Mechanical Properties of 3D-Printed Polyurethane Composites by Incorporating Hydroxylated Boron Nitride Functional Fillers.

Recently, the use of fused deposition modeling (FDM) in the three-dimensional (3D) printing of thermal interface materials (TIMs) has garnered increasing attention. Because fillers orient themselves along the direction of the melt flow during printing, this method could effectively enhance the thermal conductivity of existing composite materials. However, the poor compatibility and intensive aggregation of h-BN fillers in polymer composites are still detrimental to their practical application in thermally conductive materials. In this study, hydroxyl-functionalized boron nitride (OH-BN) particles were prepared by chemical modification and ultrasonic-assisted liquid-phase exfoliation to explore their impact on the surface compatibility, mechanical properties and the final anisotropic thermal conductivity of thermoplastic polyurethane (TPU) composites fabricated by FDM printing. The results show that the surface-functionalized OH-BN fillers are homogeneously dispersed in the TPU matrix via hydrogen bonding interactions, which improve the interfacial adhesion between the filler and matrix. For the same concentration of loaded filler, the OH-BN/TPU composites exhibit better mechanical properties and thermal conductivities than composites incorporating non-modified h-BN. These composites also show higher heat conduction along the stand-vertical direction, while simultaneously exhibiting a low dielectric constant and dielectric loss. This work therefore provides a possible strategy for the fabrication of thermal management polymers using 3D-printing methods.

Mussel-inspired interfacial reinforcement of thermoplastic polyurethane based energetic composites

The interfacial interaction and the microstructure evolution play a vital role in the mechanical properties of thermoplastic polyurethane (TPU) based energetic composites. In this work, inspired by the strong adhesion of mussels, 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane (CL-20) energetic crystals were coated with polydopamine (PDA) via in-situ polymerization of dopamine and then dispersed in TPU matrix. The core-shell structure of CL-20@PDA was confirmed by in-depth structural characterizations. The uniform and compact PDA shell gave rise to a high thermal stability with phase transition temperature of CL-20 crystals increased by 11.5 °C. Moreover, the PDA modification endowed the TPU based composites with excellent mechanical properties. A striking increase in mechanical properties and creep resistance was achieved with 6 h polymerization time of PDA. Compared with the PBX-Raw with untreated CL-20 crystals, the compressive and tensile strength after PDA coating increased by 115% and 57%, and the compressive and tensile fracture energy increased by 148% and 68%. The storage modulus at 25 °C was 40% higher than PBX-Raw. The enhancement effectivity could be ascribed to both interfacial interaction and the microstructure evolution of TPU binder. The theoretical simulations by molecular dynamics demonstrated the strong interfacial interaction mechanism between CL-20 and PDA. Moreover, the abundant hydrogen bonds between the hard segments of TPU and functional groups of PDA facilitated the formation of more hard microdomains which acted as physical crosslinking points to promote the phase separation. This work provides a potential method for the mechanical and thermal enhancement for TPU based energetic materials based on dopamine chemistry.

Reduced graphene oxide coated poly-methyl methacrylate beads based thermoplastic polyurethane nanocomposites for gas sensing applications

ABSTRACT We have fabricated, reduced graphene oxide (rGO) coated poly methyl methacrylate (PMMA) based thermoplastic polyurethane (TPU) nanocomposites for NO2 gas sensing. The rGO-coated PMMA beads and MWCNTs were incorporated into the TPU matrix in different concentrations by melt mixing. The characterization was done to confirm the preparation of the nanocomposites. The rGO-coated PMMA-TPU nanocomposites exhibit excellent electrical conductivities and efficient NO2 gas sensing. The developed sensor can sense NO2 at room temperature with the highest response time of 19 s and an average response time of 23.67 s. The sensor is recovered within 31.4 s and has a limit of detection of 9.51 ppm.

Surface-modified carbon fiber for enhanced electromagnetic interference shielding performance in thermoplastic polyurethane composites

There has been a growing interest in developing carbon-based polymer composites for electromagnetic interference (EMI) shielding materials. To achieve a high EMI shielding performance, the morphology of fillers in composites must be controlled. Although carbon fibers (CFs) have remarkable thermal and electrical properties and low density, their poor dispersion behavior within polymer matrix limits their practical applications as EMI shielding materials. In this study, we report an efficient method to disperse CFs within a thermoplastic polyurethane (TPU) matrix using pyranine-functionalized polyether (polyether–pyranine) as a dispersing agent. polyether–pyranine was grafted on the CF surfaces through π–π interactions between the CF and pyranine groups to produce surface-modified CFs (SCFs). Compared to CFs, the SCFs exhibited an improved dispersion stability within a TPU polymer matrix. Furthermore, a TPU composite with SCFs achieved an enhanced electrical conductivity and EMI shielding performance, which was primarily ascribed to the increased structural connectivity between the SCFs due to excellent dispersion.

Fabrication of thermoplastic polyurethane composites with a high dielectric constant and thermal conductivity using a hybrid filler of CNT@BaTiO3

Thermoplastic polyurethane composites with an excellent dielectric constant and high thermal conductivity were obtained using CNT@BaTiO3 as a filler through a low-speed melt extrusion method. Before preparing the hybrid filler for the composite, the filler particles were surface modified to ensure that the outer surfaces could facilitate the reaction among particles to form the hybrid and ensure complete dispersion in the thermoplastic polyurethane matrix. After confirming the proper surface treatment of the filler particles using infrared spectroscopy, thermal degradation analysis and field emission scanning electron microscopy, they were used to prepare the composite materials at a processing temperature of 200 °C. The thermal stability, thermomechanical properties, mechanical properties, thermal conductivity, and dielectric properties of the composites were investigated. Compared to the neat thermoplastic polyurethane matrix, the prepared composite exhibited a higher thermal stability, approximately 300% higher storage modulus, higher tensile strength and elongation at break values, approximately three times higher thermal conductivity (improved from 0.19 W/(m.K) to 0.38 W/(m.K), and approximately five times larger dielectric constant at high frequencies (at 1 MHz a dielectric constant of 19.2 was obtained).

The roles of T-ZnOw and MoS2 particles in the friction-induced vibration reducing the process of polymer

A novel thermoplastic polyurethane (TPU) matrix composite was combined with tetra-needle zinc oxide whisker (T-ZnOw) and molybdenum disulfide (MoS2) particles. Frictional vibration experiments were conducted to study the effect of T-ZnOw and MoS2 particles on frictional vibration behaviors. The tribological properties and vibration behaviors of TPU composites were synthetically analyzed to reveal the effects of T-ZnOw and MoS2 on the friction excitation force and vibration reduction properties. The results showed that T-ZnOw enhanced anti-deformation property, and MoS2 weakened the friction excitation force in the friction process, which resulted in a lower coefficient of friction (COF) with a small amplitude, and eliminated the high-frequency vibration amplitude. In addition, the particle composition of 6% T-ZnOw and 9% MoS2 was controlled to obtain a low COF and the best vibration reduction properties. The knowledge obtained herein contributes to the understanding of the synergistic effects of T-ZnOw and MoS2 on COF and vibration reduction behaviors, and the development of a water-lubricated TPU composite stern tube bearing with low COF and good vibration reduction properties.

Self-assembled double core-shell structured zeolitic imidazole framework-8 as an effective flame retardant and smoke suppression agent for thermoplastic polyurethane

The addition of traditional flame retardant additives can usually significantly reduce the flammability of thermoplastic polyurethane (TPU) but has a limited contribution to suppressing smoke release during combustion. To overcome this obstacle, a double core-shell structured zeolite imidazole framework-8 (ZIF-8) in combination with negatively charged phytic acid and positively charged hyperbranched polysiloxane (NH2-HBPSi) was layer-by-layer self-assembled through the electrostatic method. The decorated NH2-HBPSi layer effectively improved the interfacial compatibility between the fillers and the TPU matrix. The peak heat release rate (PHRR), total heat release (THR), total smoke production (TSP), and total CO production (TCOP) of the TPU composite containing 2.0 wt% ZIF-8@PA@NH2-HBPSi were reduced by 35.2%, 25.2%, 65.5%, and 52.8%, respectively, as compared to those of pure TPU. The distinguished fire resistance and smoke suppression were ascribed to the flame retardant effects of Zn, N, P, and Si elements in the ZIF-8@PA@NH2-HBPSi hybrid. In addition, the TPU/ZIF-8@PA@NH2-HBPSi composite maintained a high elongation at break of 2178.2% and tensile strength of 46.87 MPa due to the steric effect of NH2-HBPSi. This work presents a feasible strategy for the design and development of flame retardant fillers to improve fire resistance and inhibit smoke emission while maintaining the high ductility of TPU.

Amino Acid-Assisted Sand-Milling Exfoliation of Boron Nitride Nanosheets for High Thermally Conductive Thermoplastic Polyurethane Composites.

Boron nitride nanosheets (BNNSs) show excellent thermal, electrical, optical, and mechanical properties. They are often used as fillers in polymers to prepare thermally conductive composites, which are used in the production of materials for thermal management, such as electronic packaging. Aside from the van der Waals force, there are some ionic bond forces between hexagonal boron nitride (h-BN) layers that result in high energy consumption and make BNNSs easily agglomerate. To overcome this issue, L-lysine (Lys) was first employed as a stripping assistant for preparing graft-functionalized BNNSs via mechanical sand-milling technology, and the obtained Lys@BNNSs can be added into thermoplastic polyurethane (TPU) by solution mixing and hot-pressing methods to prepare thermally conductive composites. This green and scalable method of amino acid-assisted sand-milling can not only exfoliate the bulk h-BN successfully into few-layer BNNSs but also graft Lys onto the surface or edges of BNNSs through Lewis acid-base interaction. Furthermore, benefiting from Lys's highly reactive groups and biocompatibility, the compatibility between functionalized BNNSs and the TPU matrix is significantly enhanced, and the thermal conductivity and mechanical properties of the composite are remarkably increased. When the load of Lys@BNNSs is 3 wt%, the thermal conductivity and tensile strength of the obtained composites are 90% and 16% higher than those of the pure TPU, respectively. With better thermal and mechanical properties, Lys@BNNS/TPU composites can be used as a kind of heat dissipation material and have potential applications in the field of thermal management materials.

FDM printed MXene/MnFe2O4/MWCNTs reinforced TPU composites with 3D Voronoi structure for sensor and electromagnetic shielding applications

Wearable sensors with a three-dimensional (3D) structural design and electromagnetic shielding performance are significant for the future development of wearable electronic devices. However, it remains a challenge to achieve the target goals. Herein, the thermoplastic polyurethane (TPU)/Ti3C2Tx (MXene)/MnFe2O4/Multi-walled carbon nanotubes (MWCNTs) (i.e., TMMM) composites were innovatively designed using parametric Voronoi structure with different pore sizes and porosity upon fused deposition molding (FDM) printing. The two-dimensional (2D) MXene/zero-dimensional (0D) MnFe2O4 hybrid fillers were built initially by electrostatic bonding strategy, followed by adding the one-dimensional (1D) MWCNTs as a conductive bridging agent, this way endowed the nanofillers with different dimensions uniformly dispersed to form a superb conductive network structure in the TPU matrix. When applied as pressure sensors, the TMMM composites exhibited adjustable gauge factor (GF = 1.33–3.73), extensive sensing compression range (∼89% strain with 12.03 MPa stress), good durability (6000s cyclic compression), which was very conducive to monitoring human motion, such as finger bending, wrist bending, speech recognition, etc. The sensing mechanisms were also studied using the Finite element simulations, and the variation trend of resistance change was in good agreement with the simulation results. The average electromagnetic interference shielding efficiency (EMI SE) value of the 2.1 mm-thick printed composite reached 31.2 dB, suggesting that 99.9242% of electromagnetic waves can be shielded. The proposed strategy not only provided a solution to reduce the weight of electromagnetic shielding materials, but also provided an efficient method for developing porous 3D printed parts with adjustable sensing properties at the macroscopic scale towards wearable electronic devices.

Experimental evaluation of utilizing synthetic continuous fiber reinforcements for thermoplastics as an alternative to steel-based analogs

Despite being inexpensive and robust, steel cord reinforcements are often prone to pose risks to user health and safety in some industrial applications such as escalator handrails and rubber conveyor belts. Steel cords can reduce the overall stability and performance of the application over time due to their inherent creep accompanied by cyclic thermal expansion and contraction. In this context, this research focuses on replacing steel cords in some critical thermoplastic polyurethane (TPU) composite applications with continuous sustainable alternate synthetic fibers that possess high specific strength (e.g. carbon, glass, and Kevlar fibers). The first part of this research characterizes the effect of epoxy coating on synthetic fibers alone by studying their mechanical properties before and after modification, whereas the second half of the research involves reinforcing a TPU matrix with raw and epoxy-coated synthetic fibers to fabricate fiber-reinforced composites by compression molding. The effect of the curing temperature of epoxy on the end performance of the manufactured specimen was also tested. An in-depth analysis of mechanical and morphological studies showed that, at almost the same volume fraction of fibers, the TPU reinforced composites with modified carbon fibers showed higher load-bearing capacities than steel cord-based analogs. Conversely, a wide variety of other relevant industrial and commercial applications can potentially draw significant benefits by implementing these modified carbon/TPU composites instead of steel cords.

Electromechanical Properties of 3D-Printed Stretchable Carbon Fiber Composites.

The addition of fillers has been implemented in fused filament fabrication (FFF), and robust carbon fillers have been found to improve the mechanical, electrical, and thermal properties of 3D-printed matrices. However, in stretchable matrices, the use of fillers imposes significant challenges related to quality and durability. In this work, we show that long carbon staple fibers in the form of permeable carbon fiber cloth (CFC) can be placed into a stretchable thermoplastic polyurethane (TPU) matrix to improve the system. Four CFC sample series (nominally 53–159-µm-thick CFC layers) were prepared with a permeable and compliant thin CFC layer and a highly conductive and stiff thick CFC layer. The sample series was tested with single pull-up tests and cyclic tensile tests with 10,000 cycles and was further studied with digital image correlation (DIC) analyses. The results showed that embedded CFC layers in a TPU matrix can be used for stretchable 3D-printed electronics structures. Samples with a thin 53 µm CFC layer retained electrical properties at 50% cyclic tensile deformations, whereas the samples with a thick >150-µm CFC layer exhibited the lowest resistance (5 Ω/10 mm). Between those structures, the 106-µm-thick CFC layer exhibited balanced electromechanical properties, with resistance changes of 0.5% in the cyclic tests after the orientation of the samples. Furthermore, the suitability of the structure as a sensor was estimated.

Merkel cell-like artificial mechanoreceptor with high sensitivity and high resolution over a wide linear range

Mammalian mechanoreceptors endow the skin with the ability to perceive mechanical stimuli with precision. However, the fabrication of artificial mechanoreceptors with high sensitivity and resolution over a wide linear pressure range remains a key challenge. Herein, an artificial ion mechanoreceptor with the core-shell structured nanofibrous membrane as the sensitive layer is proposed by mimicking the biomechanical receptor. The membrane embeds ionic liquids and poly(vinylidene fluoride-co-hexafluoropropylene) hybrid nanofibers into a thermoplastic polyurethane matrix, enabling a reversible conversion between non-ionic and iontronic sensing modes induced by tactilely triggered ion movements. It exhibits a high sensitivity (32.70 kPa −1 ), a linear response (R 2 ≈ 0.999) over a wide range of 0.04 Pa to 209 kPa, and an ultra-high resolution of 0.035% at 100 kPa (far exceeding the resolution of skin of ∼7%). The receptors are further used to monitoring physiological signals (even weak fingertip pulse signals) and assembled into an array to aid object recognition. • A core-shell structured ionic nanofiber membrane is constructed • The receptor can transform from non-ionic sensing to iontronic sensing under pressure • Good compatibility between high sensitivity and high linearity • High resolution even under high preload pressure By simulating the mechanotransduction mechanism of Merkel cells, Yang et al. fabricate an artificial mechanoreceptor that modulates ion migration under external pressure, which achieves both high sensitivity (32.701 kPa −1 ) and high linearity (R 2 = 0.999). In addition, it maintains 0.035% resolution at a high preload pressure of 100 kPa.