bluuebunny/crossref_metadata_2025 huggingface dataset:
A Stretchable Filament Sensor with Tunable Sensitivity for Wearable Robotics and Healthcare Applications
Authors: Davies James , Thai Mai Thanh , Hoang Trung Thien , Nguyen Chi Cong , Phan Phuoc Thien , Phan Hoang‐Phuong , Lovell Nigel H. , Do Thanh Nho
Published: January 2023

Taking a leaf out of evolutionary biology, soft robots have begun to utilize compliant materials and structures for improved interactions with humans and complex environments. However, these advances have not been followed closely by sensing mechanisms. Biology has had a head start on the development of advanced sensing systems. The human body and its skeletal muscles can tune their morphologies to interact with the surrounding environment. Inspired by such biological systems, this paper introduces a novel hydraulic soft filament sensor (SFS) with tunable sensitivity. The SFS is a type of hydraulic pressure‐based tubular strain sensor, which has a sensing core made of a soft and stretchable micro‐sized filament filled with incompressible fluid where its inner hydraulic pressure is changed with strain. The SFS can be customized to form a wide range of configurations such as a long fiber or a skin‐like structure. To demonstrate the SFS capability, different configurations for the SFS are fabricated and experimentally validated. The scalable and tunable nature of the SFS makes it suitable for a wide range of wearable and medical applications.
Multichannel Impedance Cytometry Downstream of Cell Separation by Deterministic Lateral Displacement to Quantify Macrophage Enrichment in Heterogeneous Samples
Authors: Torres‐Castro Karina , Jarmoshti Javad , Xiao Li , Rane Aditya , Salahi Armita , Jin Li , Li Xudong , Caselli Federica , Honrado Carlos , Swami Nathan S.
Published: January 2023

The integration of on‐chip biophysical cytometry downstream of microfluidic enrichment for inline monitoring of phenotypic and separation metrics at single‐cell sensitivity can allow for active control of separation and its application to versatile sample sets. Integration of impedance cytometry downstream of cell separation by deterministic lateral displacement (DLD) for enrichment of activated macrophages from a heterogeneous sample is presented, without the problems of biased sample loss and sample dilution caused by off‐chip analysis. This requires designs to match cell/particle flow rates from DLD separation into the confined single‐cell impedance cytometry stage, the balancing of flow resistances across the separation array width to maintain unidirectionality, and the utilization of co‐flowing beads as calibrated internal standards for inline assessment of DLD separation and for impedance data normalization. Using a heterogeneous sample with un‐activated and activated macrophages, wherein macrophage polarization during activation causes cell size enlargement, on‐chip impedance cytometry is used to validate DLD enrichment of the activated subpopulation at the displaced outlet, based on the multiparametric characteristics of cell size distribution and impedance phase metrics. This hybrid platform can monitor the separation of specific subpopulations from cellular samples with wide size distributions, for active operational control and enhanced sample versatility.
Outstanding High Field‐Effect Mobility of 299 cm2 V−1 s−1by Nitrogen‐Doped SnO2Nanosheet Thin‐Film Transistor
Authors: Pooja Pheiroijam , Che Chien Chun , Zeng Shi‐Hao , Lee Yu Chieh , Yen Te‐Jui , Chin Albert
Published: January 2023

Record high field‐effect mobility (µFE) thin film transistors (TFTs) based on 5 and 7 nm thickness SnON channel layer is reported. The SnON TFT device with 7.6% nitrogen content achieves a record high µFEof 299 cm2 V−1 s−1at 7 nm thickness and 277 cm2 V−1 s−1at 5 nm thickness, compared to SnO2with µFEof 211 cm2 V−1 s−1. At the same 5 nm quasi‐2D channel thickness, this µFEof nanocrystalline SnON transistor is comparable to single crystalline Si and InGaAs metal oxide semiconductor field‐effect transistor (MOSFET) and also higher than the phonon‐scattering‐limited 2D MoS2FET. From the principle of quantum‐mechanical calculation, the high µFEof nanosheet SnON TFT is due to lower effective mass of electrons, 0.29 m0in the conduction band in contrast to 0.41 m0of SnO2. SnON can reduce the defect trap densities by introducing non‐oxide anions where the valence band can be controlled to remove or passivate the oxygen vacancy levels by substitutional alloying with nitrogen anions to circumvent instability, increase on‐current (ION) and improve the µFE. It is highly expected that the high performance quasi‐2D nanosheet SnON TFTs will be utilized in embedded DRAM and monolithic 3D integrated circuits (ICs).
Charge‐Transfer Polymeric Hydrogels with Self‐Healing, Injectable, Thermosensitive, Adhesive, and Antibacterial Properties for Diabetic Wound Healing
Authors: Zhang Ru , Liu Cuiwen , Wei Chengmeng , Huang Jingtao , Zou Xiaohui , Feng Yanxian , Ang Song , Guo Suqin , Qu Jinqing , Qing Ning , Tang Chengcheng , Zhou Xiaoqing , Chen Min , Tang Liuyan
Published: January 2023

Charge transfer (CT) complexes are self‐assembled structures with a variety of attractive properties, but little is known about their performance in the construction of polymeric hydrogels. Herein, a series of hydrogels (CT‐hydrogels) with CT complex are designed and synthesized. The CT complex, consisting of pyranine derivative (sodium 8‐((4‐vinylbenzyl)oxy)pyrene‐1,3,6‐trisulfonate, VB‐HPTS) and viologen derivative (1‐methyl‐1′‐(4‐vinylbenzyl)‐[4,4′‐bipyridine]‐1,1′‐diium chloride iodide, VB‐MV), serves as the cross‐linker, and N‐(2‐hydroxyethyl)acrylamide is used as the backbone monomer. The CT complex allows CT‐hydrogels to have rapid self‐healing property, injectability, thermosensitivity, good adhesive strength on skin, and excellent antibacterial performance against both Gram‐negative and Gram‐positive bacteria. In addition, they have good biocompatibility and long‐term stability in both ambient and aqueous environments, showing potential application as wound dressing. Their performance in diabetic wound healing displays high wound healing rate, effectively inhibits inflammatory infiltration, and promotes neovascularization as compared with commercial wound dressings. The results of this study suggest that the multifunctional CT‐hydrogels are of great value in wound healing, and show a promising future to design hydrogels with CT complexes.
A Wearable Self‐Powered Multi‐Parameter Respiration Sensor
Authors: Dai Jieyu , Meng Jianping , Zhao Xiaoming , Zhang Weiyi , Fan Yubo , Shi Bojing , Li Zhou
Published: January 2023

Respiratory disease can be early warned by many respiratory parameters such as intensity, rhythm, temperature, and breath molecules like acetone. It requires a complex process to measure these respiratory parameters simultaneously in clinical practice. Therefore, it is a hot topic to design portable devices especially wearable electronics to monitor respiratory conditions continually in daily life. Here, a flexible self‐powered multi‐parameter respiration sensor based on poly(vinylidene fluoride) (PVDF) thin film and flexible interdigital electrodes that is bonding with sodium‐doped zinc oxide nanoflowers is demonstrated , which can detect airflow, temperature, and acetone during breathing. The respiration sensor may provide some reference ways for the fabrication of miniaturized respiratory disease monitoring devices.
Washable and Flexible All Carbon Electrothermal Joule Heater for Electric Vehicles
Authors: Weerathunga Helapiyumi , Do Thu Trang , Pham Hong Duc , Jones Robert , MacLeod Jennifer , Kim TaeYoung , Dubal Deepak
Published: January 2023

Amid the rapid development of electric vehicles, a flexible and waterproof radiant heater that can withstand repeated bending and washing is highly desirable. Herein, a freestanding, ultra‐flexible, and washable joule heater is constructed using a biocompatible poly(styrene‐isoprene‐styrene) (SIBS) polymer as binder and carbon black (CB) as heating material. By controlling the amount of CB and the thickness of the film, a minimum resistivity, and conductivity of 26 mΩ cm and 7.4 S cm−1, respectively, is achieved. Remarkably, the 28% CB/SIBS film can reach a maximum temperature of 201 °C while maintaining a stable temperature at 130 °C for repeated ON/OFF cycles. Time‐of‐flight secondary ion mass spectrometry of post‐mortem material analysis shows that a 1 h stability test at 130 °C has no sign of degradation and the films remain extremely stable. The films also show exceptional electrothermal heater performance after carrying out mechanical property tests such as bending (over 30°), repetitive bending (1000 cycles), twisting (two turns), and washing (soaked in distilled water for over 12 h). These outstanding heater performances incorporate extreme chemical stability and mechanical flexibility proposing that the CB/SIBS‐based electrothermal elements hold great potential for numerous practical applications, such as heating systems in electric vehicles and wearable electronics.
Structure Control of Large‐Sized Graphene Foams for Outstanding Microwave Absorption, Thermal Insulation, and Mechanical Stability
Authors: Cheng Qi Heng , He Yu , Yang Hui Li , Mo Run Wei , Wang Jian Nong
Published: January 2023

With the rapid development of microwave technologies, electromagnetic pollution and stealth have become important problems to be solved. Although great efforts have been made in recent years, it is still a great challenge to achieve strong and broadband absorption combined with thermal and mechanical functionalities. Herein, a multi‐functional design toward three‐dimensional graphene foams (GFs) is provided. These foams are prepared to have large sizes by simple freezing and air‐drying of a structure‐integrated graphene oxide (GO) hydrogel, and polydimethylsiloxane (PDMS) is introduced to reinforce the GO framework. The remarkable finding is that the GF/PDMS composite possesses strong broad band absorption (reflection loss < ‐10 dB) over the entire frequency range of radar microwaves (2–18 GHz). This is attributed to the synergistic effects of dielectric loss of the GO material itself and the multi‐layer attenuation brought by the porous foam structure. Experimental results also show that the light foams have very low thermal conductivity of 0.03–0.13 W m−1 k−1 and mechanical flexibility for compression, extension, and torsion. Therefore, this study provides a new strategy for large‐scale production of multifunctional microwave absorbing foam materials for applications in both civil and military fields.
Assessment of Wafer‐Level Transfer Techniques of Graphene with Respect to Semiconductor Industry Requirements
Authors: Wittmann Sebastian , Pindl Stephan , Sawallich Simon , Nagel Michael , Michalski Alexander , Pandey Himadri , Esteki Ardeshir , Kataria Satender , Lemme Max C.
Published: January 2023

Graphene is a promising candidate for future electronic applications. Manufacturing graphene‐based electronic devices typically requires graphene transfer from its growth substrate to another desired substrate. This key step for device integration must be applicable at the wafer level and meet the stringent requirements of semiconductor fabrication lines. In this work, wet and semidry transfer (i.e. wafer bonding) are evaluated regarding wafer scalability, handling, potential for automation, yield, contamination, and electrical performance. A wafer scale tool is developed to transfer graphene from 150 mm copper foils to 200 mm silicon wafers without adhesive intermediate polymers. The transferred graphene coverage ranges from 97.9 % to 99.2 % for wet transfer and from 17.2 % to 90.8 % for semidry transfer, with average copper contaminations of 4.7 × 1013 (wet) and 8.2 × 1012 atoms/cm2 (semidry). The corresponding electrical sheet resistance extracted from terahertz time‐domain spectroscopy varied from 450 to 550 Ω sq−1 for wet transfer and from 1000 to 1650 Ω sq−1 for semidry transfer. Although the wet transfer is superior in terms of yield, carbon contamination level, and electrical quality, wafer bonding yields lower copper contamination levels and provides scalability due to existing industrial tools and processes. Our conclusions can be generalized to all 2D materials.
Robust and Elastic Bioinspired MXene‐Coated Foams with Enhanced Energy Storage and Conversion Capabilities
Authors: Jiang Degang , Bacal Christine Jurene O. , Usman Ken Aldren S. , Zhang Jizhen , Qin Si , Hegh Dylan , Lei Weiwei , Liu Jingquan , Razal Joselito M.
Published: January 2023

Constructing highly porous structures using Ti3C2Tx MXene provides a promising strategy toward achieving low density, high specific surface area, and shorter ion/molecule transport paths. However, the weak MXene‐MXene or MXene‐substrate interactions hinder the development of ultra‐robust and elastic MXene‐based architectures. To address this issue, a bio‐inspired strategy is developed to effectively adhere the MXene nanosheets onto melamine foam via covalent and hydrogen bonding interactions through polyethyleneimine/polydopamine‐modification. The enhanced interactions contribute to high MXene loading (≈94 wt.%) and reversible compressibility even after 10 000 compression/release cycles at 80% strain. The compressible supercapacitor device assembled from this foam exhibits high energy storage capability (119 F g−1 at 2 mV s−1) with capacitance retention of ≈93% after 1000 compression/release cycles at 50% strain. Moreover, the presence of polydopamine and MXene enable the absorption of light in the UV–Vis and near‐IR regions, respectively, inducing photothermal conversion functionality, with an evaporation rate of ≈1.5 kg m−2 h−1 and ≈89% solar evaporation efficiency under one sun illumination. It is envisaged that this bio‐inspired chemical modification offers a versatile strategy for the assembly of MXene nanosheets onto different substrates for various applications, such as electromagnetic interference shielding, energy storage, and conversion.
Electroformed Inverse‐Opal Nanostructures for Surface‐Marker‐Specific Isolation of Extracellular Vesicles Directly from Complex Media
Authors: Lin Andrew A. , Jiang Zhimin , Yee Stephanie S. , Carpenter Erica L. , Pikul James H. , Issadore David
Published: January 2023

Extracellular vesicles (EVs) – nanoscale membranous particles that carry multiple proteins and nucleic acid cargoes from their mother cells of origin into circulation – have enormous potential as biomarkers. However, devices appropriately scaled to the nanoscale to match the size of EVs (30–200 nm) have orders of magnitude too low throughput to process clinical samples (1012 EVs mL−1 in serum). To address this challenge, we develop a novel approach that incorporates billions of nanomagnetic sorters that act in parallel to precisely isolate sparse EVs based on immunomagnetic labeling directly from clinical samples at flow rates billions of times greater than that of a single nanofluidic device. To fabricate these chips, the ferromagnetic metals are electro‐deposited into a self‐assembled microlattice, achieving >109 nanoscale magnetophoretic sorting devices in a 3D postage stamp‐sized lattice with >70x magnetic traps and >20x enrichment of magnetic nanoparticles versus our previous work. The immunomagnetically labeled EVs are isolated and achieve a ≈100% increase in yield as well as increased purity compared to conventional methods. Building on the proof‐of‐concept demonstrations in this manuscript, this new approach has the potential to enhance the future clinical translation of EV biomarkers by enabling rapid, sensitive, and specific isolation of EV subpopulations from clinical samples.
3D Printing of Carbon Nanotube (CNT)/Thermoplastic Polyurethane (TPU) Functional Composites and Preparation of Highly Sensitive, Wide‐range Detectable, and Flexible Capacitive Sensor Dielectric Layers via Fused Deposition Modeling (FDM)
Authors: Yang Leipeng , Liu Xin , Xiao Yuan , Zhang Yongyan , Zhang Gaiping , Wang Yuping
Published: January 2023

As one of the widely used additive manufacturing technologies, FDM has been limited by small variety of available materials, poor mechanical properties, and lack of functionality of the FDM‐printed parts. In this study, CNT/TPU filaments are prepared, and their thermal behavior is determined to lay the foundation for FDM process. The effects of the CNT content on the mechanical and conductivity properties of FDM‐printed samples are investigated, and the FDM‐printed CNT/TPU dielectric layers are explored for capacitive sensing applications. The results show that the incorporation of CNT significantly affects their mechanical, electrical, and capacitive sensing properties. The addition of 6 wt.% CNT increases the tensile strength by 199%, the flexural strength by 34%, and the electrical resistivity from 1.35 × 1010 to 7.26 × 103 Ω sq−1. The sensitivity of the sensor with the FDM‐printed CNT/TPU dielectric layer microstructure is 0.04034 kPa−1 (0–20 kPa). The prepared CNT/TPU sensors have the advantages of wide detection range (0–800 kPa), a rapid response time (60 ms), and good repeatability, and have potential applications in detecting physical pressure, human motion, and human‐computer interaction. In conclusion, the CNT/TPU composite prepared in this study increases the types of suitable materials for FDM and expands the application potential of FDM.
Flow Casting Soft Shells with Geometrical Complexity and Multifunctionality
Authors: Fan Dongliang , Liao Yuxuan , Wu Wenyu , Zhang Ping , Yang Xin , Zhu Renjie , Wang Yifei , Yang Canhui , Wang Hongqiang
Published: January 2023

Soft shells are ubiquitous in soft devices, e.g., soft robots, wearable sensors, and soft medial replicas. However, previous widely accepted methods, such as mold casting, dip coating, and additive manufacturing, are limited to thick shells due to the mold assembly and the large friction during demolding, long processing time for mold dissolution, and poor scalability, respectively. Here, a facile, robust, and scalable manufacturing technique, named flow casting, to create soft shells with complex geometries and multifunctionalities is proposed. The method involves a flow‐governed layer casting process and a peel‐dominated demolding process. A one‐dimensional soft shell is first made with controllable thicknesses (100–400 µm) and fabricated various soft shells of intricate geometries, including three‐branched, circular‐shaped, and exquisite microstructures such as papillae and microgrooves on curved surfaces, with the resolution of feature sizes on the order of 100 µm. Furthermore, the versatility of this method is demonstrated with a 3D vascular phantom model for a magnetic robot transporting, microstructured cubic sleeves for enhancing the grasping ability of rigid grippers, and a stretchable optical waveguide capable of color changing by external mechanical stimuli.
Imparting Multi‐Scalar Architectural Control into Silk Materials Using a Simple Multi‐Functional Ice‐Templating Fabrication Platform
Authors: Joukhdar Habib , Och Zachary , Tran Hien , Heu Celine , Vasquez Gabriel Matus , Sultana Nawreen , Stevens Michael , Dokos Socrates , Lim Khoon S. , Lord Megan S. , Rnjak‐Kovacina Jelena
Published: January 2023

Human tissues and organs exhibit complex hierarchical and gradient structures that are essential to their function and should be recapitulated within biomaterial scaffolds targeting their regeneration. Unidirectional freezing, an ice templating technique where ice acts as a porogen, is uniquely suited to recapitulating the architectural anisotropy, gradients, and hierarchical transitions of human tissues, but ice templating of polymeric systems, including silk fibroin, remains less well understood than their colloidal counterparts. To address this, a versatile and accessible freezing setup for silk that allows tuning of freezing parameters including the polymer cooling rate (30 °C min−1 to 2 °C min−1) and ice solidification velocity (2.5 to 0.6 mm min−1) using liquid nitrogen, is developed. Real time visual and thermal monitoring of the freezing process for multiple silk concentrations (2–10% wt/v) and material states (liquid, hydrogels) is performed and the conditions are correlated with pore morphology. Unprecedented control over pore size (100–90 000 µm2) and pore morphology (cellular–lamellar), consistent pore alignment, and generation of gradient porosity in silk scaffolds are demonstrated. For the first time, impact of shear thinning behavior of silk in ice crystal formation is demonstrated, showing non‐linear and complex freezing phenomena in silk.
Variable Stiffness Actuators with Covalently Attached Nanofragments that Induce Mineralization
Authors: Cao Danfeng , Martinez Jose G. , Hara Emilio Satoshi , Jager Edwin W. H.
Published: January 2023

Soft robotics has attracted great attention owing to their immense potential especially in human–robot interfaces. However, the compliant property of soft robotics alone, without stiff elements, restricts their applications under load‐bearing conditions. Herein, biohybrid soft actuators, that create their own bone‐like rigid layer and thus alter their stiffness from soft to hard, are designed. Fabrication of the actuators is based on polydimethylsiloxane (PDMS) with an Au film to make a soft substrate onto which polypyrrole (PPy) doped with poly(4‐styrenesulfonic‐co‐maleic acid) sodium salt (PSA) is electropolymerized. The PDMS/Au/PPy(PSA) actuator is then functionalized, chemically and physically, with plasma membrane nanofragments (PMNFs) that induce bone formation within 3 days, without using cells. The resulting stiffness change decreases the actuator displacement; yet a thin stiff layer cannot completely stop the actuator's movement, while a relatively thick segment can, but results in partial delamination the actuator. To overcome the delamination, an additional rough Au layer is electroplated to improve the adhesion of the PPy onto the substrate. Finally, an alginate gel functionalized with PMNFs is used to create a thicker mineral layer mimicking the collagen‐apatite bone structure, which completely suppresses the actuator movement without causing any structural damage.
A 3D Nanomaterials‐Printed Wearable, Battery‐Free, Biocompatible, Flexible, and Wireless pH Sensor System for Real‐Time Health Monitoring
Authors: NajafiKhoshnoo Sahar , Kim Taeil , Tavares‐Negrete Jorge A , Pei Xiaochang , Das Prativa , Lee Sang Won , Rajendran Jerome , Esfandyarpour Rahim
Published: January 2023

The pH sensing devices can provide important health information with applications in infection detection, disease diagnosis, and personalized medicine. However, these devices are often expensive with modest flexibility and require bulky readout instruments, thus inappropriate for wearable, remote, and continuous health monitoring applications. Herein, an integrated, miniaturized, modular, wearable, battery‐free, biocompatible, flexible, 3D‐printed (WB2F3D) sensor system for on‐demand, continuous, wireless, and real‐time pH monitoring is proposed, developed, and fully characterized. The 3D‐printing of nanomaterials on skin‐like flexible substrates is innovatively applied to enable multimaterial and multilayer printing of the sensors, reusable electronic/communication circuity, and antennas in a tailorable, low‐cost, and time‐efficient manner. The battery‐free and flexible readout system is designed to enable wireless and on‐demand energy and data transmission for continuous and real‐time pH monitoring. This sensor system exhibits high sensitivity (≈|51.76| mV pH−1), specificity, repeatability, reproducibility toward various pH ranges (3.0–10.0), excellent mechanical flexibility, and outstanding biocompatibility (cell viability > = 90%). It successfully demonstrates the pH change monitoring in an ex situ hydrogel‐based wound model. The WB2F3D sensor system is envisioned to provide an integrated platform for accurate, on‐demand, battery‐free, wireless, and real‐time human health monitoring, and another step toward personalized medicine.
Localization of Multiple Hydrogels with MultiCUBE Platform Spatially Guides 3D Tissue Morphogenesis In Vitro
Authors: Suthiwanich Kasinan , Hagiwara Masaya
Published: January 2023

Localization of multiple hydrogels is expected to develop the structure of 3D tissue models in a location‐specific manner. Here, 3D tissue morphogenesis is spatially guided by localizing different hydrogel conditions at different parts of a tissue. To achieve the localization, a unit‐based scaffold is developed with a unique frame design to trap hydrogel solutions inside their designated units. An optimal range of unit dimensions and surface wettabilities enables a solution trapping up to several cubic millimeters without any need for chemical additives. This capability allows spatial organization of biomolecular compositions and physical conditions of hydrogels, as well as the relative position of biological samples (cells, spheroids, and reconstituted tissues) within the scaffold. Successful localization of branching development on reconstituted human epithelial tissues is achieved by localizing growth factors or cross‐linked matrix proteins within hydrogels, demonstrating a direct dependence on local hydrogel conditions. Unlike 3D‐bioprinting or microfluidic techniques, this scaffold‐based localization of hydrogels requires only a manual pipetting and no specialized tools, making it ready‐to‐use for researchers from any field. This localization technique provides a new promising route to spatially control morphogenesis, differentiation, and other developmental processes within 3D organoids or tissue models for practical biomedical applications in the future.
Flexible Vitrimers for Self‐healable Triboelectric Nanogenerators
Authors: Ye Chongnan , Li Wenjian , Voet Vincent S.D. , Folkersma Rudy , Pei Yutao , Loos Katja
Published: January 2023

Despite rapid advancements in the development of triboelectric nanogenerators (TENG), mechanical defects generated during their working condition limit the service lifetime of these devices. Polyester‐based vitrimers can offer a solution to solve this issue via their dynamic bond exchange reactions. However, they often require high temperatures and a long time to crosslink, rendering them not useful for large‐scale TENG fabrication. To solve these issues, a self‐healable vitrimer‐based triboelectric nanogenerator (VITENG) is developed based on diacrylate poly(dimethylsiloxane) (AA‐PDMS) via a fast thiol‐Michael reaction. By including 2,3‐dihydroxypropyl methacrylate (DHPMA), hydroxy end dangling side chains are generated in the matrix, which increase the PDMS network's flexibility and transesterification efficiency. Efficient transesterification occurs on the abundant dynamic β‐hydroxy ester bonds in the PDMS network, resulting in 100% efficient mechanical damage repair. The VITENG demonstrates a good performance with an output voltage of 135 V under a load of 10 N, demonstrating the potential for mechanical energy harvesters with long lifetimes and high design flexibility.
Room‐Temperature NH3 Sensor Based on SnO2 Quantum Dots Functionalized SnS2 Nanosheets
Authors: Bai Jinzhou , Shen Yanbai , Zhao Sikai , Li Ang , Kang Zhangke , Cui Baoyu , Wei Dezhou , Yuan Zhenyu , Meng Fanli
Published: January 2023

Traditional metal oxide semiconductor gas sensors are facing significant challenges for portable devices and integration due to large power consumption caused by high working temperature. 2D nanomaterials with large specific surface areas, rich active sites, and tunable electrical properties are proved to be promising candidates for room‐temperature gas sensors. However, several disadvantages including weak response, sluggish response/recovery kinetics, and poor selectivity still need to be overcome for high‐performance gas sensors. Herein, SnO2 quantum dots (QDs) with a diameter of ≈3 nm functionalized SnS2 nanosheets with a thickness of ≈17 nm are synthesized via a two‐step solvothermal method, which exhibits a high response of 11.1 to 100 ppm NH3 at room temperature of 25 °C with fast response speed and good repeatability, high selectivity, and long‐term stability. The sensing mechanism is mainly ascribed to 0D/2D heterostructure, synergistic effect, and n‐n heterojunction constructed across the interfaces between SnO2 QDs and SnS2 nanosheets. The as‐prepared nanomaterials may contribute to the reasonable design of heterostructure between 0D QDs and 2D nanomaterials, and offer a promising candidate for room‐temperature NH3 detection.
Sustainable Additive Manufacturing of Polyelectrolyte Photopolymer Complexes
Authors: Kolibaba Thomas J. , Higgins Callie I. , Crawford Nathan C. , Samaniuk Joseph R. , Killgore Jason P.
Published: January 2023

Polyelectrolyte complexes (PECs), assemblies of oppositely charged polymers with powerful properties and wide‐ranging applications, are currently not melt‐processable via any conventional means and have been limited commercially to applications only as coatings. Herein, a unique strategy of pairing a polycation with an oppositely charged photopolymerizable monomer is employed. Vat photopolymerization of this mixture yields 3D spatial control over PECs for the first time. The properties of these 3D‐printed PECs are evaluated and are found to be similar to conventionally studied PEC materials. The water sensitivity of the PEC parts is adjustable through the incorporation of a small amount of a hydrophilic covalent crosslinker, highlighting potential future applications of these materials in 4D printing. Finally, the upcyclability of the additively manufactured PECs is demonstrated through the dissolution of a printed part and its incorporation into virgin resin to yield a part composed of partially recycled material. This chemistry has the potential to dramatically expand the application space of PEC materials and is a step towards a more circular economy for the field of additive manufacturing.
Pattern Transformation Inspired Multifunctional Cylindrical Vessels with Programmable Stoma‐Shaped Biomimetic Openings
Authors: Sun Jiabin , Zhou Zhenhuan , Cao Xueqing , Zhang Qifeng , Zhang Qilin , Jia Ziguang , Sun Wei , Tong Zhenzhen , Xu Xinsheng , Lim C.W.
Published: January 2023

Pattern transformation in a periodic porous structure has inspired multifarious mechanical metamaterials/metastructures due to the induced unusual negative Poisson's ratio behavior of macroscopic materials. Recently, it has been leveraged to architect a variety of designable and multifunctional structural members. Inspired by this design methodology, a novel porous cylindrical shell, which is perforated by a large number of staggered openings, is constructed and investigated meticulously. A stable, anti‐disturbed, and controllable waisted deformation of the architected cylindrical shell will be triggered under an axial compression. A stoma‐shaped biomimetic hole and graded distribution of initial openings are proposed to ensure that the holes distributed throughout the shell can be closed up concurrently while the closed states of holes can be flexibly programmed. To explore the applications of such shells, a handy cylindrical vessel is elaborately designed and its multiple functions including reagent release, underwater sampling, and flow control are exhibited by experiments. The results reflect that the designed vessel can be facilitated with many advantages such as uniform release, quick action, easy actuation, and repeated usage. Moreover, it also may open a new avenue for metamaterials in the fields of biomedical engineering, underwater detection, fluid machinery, etc.
Air‐Permeable Textile Bioelectronics for Wearable Energy Harvesting and Active Sensing
Authors: Zhao Xun , Chang Austin , Li Justin , Xu Jing , Hollister John , Che Ziyuan , Wan Xiao , Yin Junyi , Wang Shaolei , Lee Shinyoung , Kavehpour Pirouz , Chen Jun
Published: January 2023

Advances in wearable bioelectronics enable the possibility of transforming the currently reactive and disease‐centric healthcare system to one focused on disease prevention and health promotion. Converting biomechanical activities into electrical signals could be a unique way to develop wearable bioelectronics for personalized healthcare. In this work, an air‐permeable textile (APT) bioelectronics is developed. It is formed with a liquid metal electrode treated with Nickel (Ni‐EGaIn) encapsulated between two layers of electrospun Polycaprolactone textile. With a size of 4 cm by 4 cm, the APT bioelectronics produces an open‐circuit voltage of 12 V and a short‐circuit current of 0.12 mA, ultimately outputting a power density of 7.975 W m−2. The APT bioelectronics demonstrates an ability to produce electrical output under varying degrees of deformation with stable performance over 6000 cycles. In addition, the APT bioelectronics holds a drying rate of 5.07% min−1 compared to conventional fabrics such as polyester with a drying rate of 3.93% min−1. This keeps the ATP dry and cool for decent wearing comfort. With a collection of compelling features, the air‐permeable textile bioelectronics represents a promising approach for human body centered energy and sensing applications.
An Anisotropic Dielectric Elastomer Actuator with an Oriented Electrospun Nanofiber Composite Film
Authors: Zhang Yang , Chen Zhiwen , Xu Feng , Lin Jiawei , Zhu Bin , Xu Zhenjin , Zhou Gang , Zhang Shaohua , Chen Qinnan , Wang Lingyun , Wu Dezhi
Published: January 2023

Anisotropic actuation, a universal phenomenon in nature, may be inspiring for the development of intelligent soft robotics in the future. For dielectric elastomers (DEs), important investigations have been done to decrease the voltage and increase the actuation strain. However, mechanical isotropy of synthetic DEs shows in‐plane uniform deformation, lacking the controllability of the actuation direction. Herein, an anisotropic DE (denoted as ADE) is constructed by casting Ecoflex/BaTiO3 solution onto oriented TPU nanofibrous membranes fabricated via drum electrospinning. The resulting ADE with a seamless three‐layer structure features mechanical anisotropy in the elastic modulus, with the maximum ratio between x and y directions of the plane being 11. A prototype ADE‐based actuator demonstrates a high electroactuation anisotropy of 3.95, a large unidirectional length strain of 15%, and a high energy density of 0.014 MJ m−3 at an electric field of 40 V µm−1. Two potential applications, a flow divider valve simulating the Transwell test in the medical field and a mechanical stimulus component mimicking the maturation of cardiomyocytes, are successfully demonstrated. Thus, this work offers a versatile yet simple approach for fabricating anisotropic electroactive elastomer actuators in the future.
Controlling the Inkjet Printing Process for Electrochemical (Bio)Sensors
Authors: Pradela‐Filho Lauro A. , Gongoni Juliana L. M. , Arantes Iana V. S. , De Farias Davi M. , Paixão Thiago R. L. C.
Published: January 2023

Inkjet printing is a popular technique for depositing high‐precision ink lines. This study reports the printing parameters’ influence on the electrical properties of the sensing devices. The electrochemical sensors are fabricated with a commercial piezoelectric printer and silver ink. Different substrates are evaluated in the printing process, including paper, polyimide, and polyvinyl chloride (PVC) tapes. Ink depositions’ temperature, ink drop spacing, length, and the number of the ink layer are also evaluated in this study. Higher temperatures (40 °C) make the substrate surface smoother, improving the printing quality. Controlling the ink drop spacing produces narrow continuous ink lines. The number of ink layers changes the film thickness, altering their electroactive surface area. The best printing parameters are PVC tape at 40 °C, 17 µm drop spacing, one layer, and 13 mm length. Under optimized conditions, three‐electrode electrochemical systems are fully printed with silver ink, showing batch‐to‐batch reproducibility (RSD = 3%). Their analytical performance is evaluated for picric acid, hydrogen peroxide, and glucose quantification. The sensors are modified with glucose oxidase to quantify glucose in artificial saliva, confirming their analytical applicability. Therefore, this work reports fundamental aspects of inkjet printing, bringing valuable findings to guide new research involving inkjet‐printed electrochemical biosensors/sensors ((bio)sensors).
Nitrogen‐Doped Multilayer Graphene Microtubes for High‐Density Recording of Occipital EEG Signals
Authors: Zhang Chengcheng , Li Mingji , Xuan Xiuwei , Zhou Baozeng , Li Penghai , Li Hongji
Published: January 2023

Graphene microelectrodes exhibit potential in recording high‐density electroencephalography (EEG) signals from various brain regions. In this study, microtubes composed of nitrogen‐doped graphene (NG) nanosheets are synthesized by chemical vapor deposition to record high‐density EEG signals. The N‐content of the NG samples ranges from 1.35 to 2.22 at.%. One of the fabricated microtubes with an N‐content of 2.22% exhibits low scalp‐contact resistance and high signal‐to‐noise ratio (SNR) of EEG signals. The NG‐microtube has the advantages of high water‐retention, scalp affinity, water absorption, salt interception, and low resistance; these advantages reduce the scalp‐contact resistance and improve the response of EEG signals. Furthermore, an occipital 24‐lead EEG sensor with 72 optimized NG microtubes is assembled to record spontaneous and visually evoked EEG signals. Untrained volunteers are asked to wear the NG‐EEG sensor, and thus, spontaneous EEG with a high SNR and visually evoked EEG signals with an interval of 0.1 Hz are obtained easily. The occipital NG‐based EEG sensor is convenient to wear and can identify high‐density EEG signals. Therefore, the EEG sensor is not only suitable for the peripheral fine control of motion imagination but also used in the clinical diagnosis of functional disorders in various brain regions, promoting the development of healthcare electronics.
Optimizing Surface Composition and Structure of FeWO4 Photoanodes for Enhanced Water Photooxidation
Authors: Ta Xuan Minh Chau , Nguyen Thi Kim Anh , Bui Anh Dinh , Nguyen Hieu T. , Daiyan Rahman , Amal Rose , Tran‐Phu Thanh , Tricoli Antonio
Published: January 2023

Photoelectrochemical water splitting is a promising approach to produce green hydrogen using solar energy. A primary bottleneck remains the lack of efficient photoanodes to catalyze the sluggish water photooxidation reaction. Engineering photoabsorbers with a narrow bandgap and suitable band edge can boost the photoelectrochemical performance. Herein, nanostructured iron tungstate (FeWO4) photoanodes are engineered directly on a fluorine doped tin oxide glass substrate via a scalable and ultra‐fast flame synthesis route in 13 seconds. Physiochemical, optoelectronic, and electrochemical properties of these photoanodes are systematically investigated. The key roles of charge transport, transfer, and dissolution of W and Fe ions from the FeWO4 matrix within long‐term performance are revealed. Optimal FeWO4 photoanode with a bandgap of 1.82 eV and a FeOOH/NiOOH co‐catalyst coating shows an improved water photooxidation performance, reaching a photocurrent density of 0.23 mA cm−2 at 1.4 V versus reversible hydrogen electrode in 1 m potassium hydroxide. It further demonstrates relatively good photostability, maintaining ≈96% of photocurrent density after 1‐hour continuous photooxidation, albeit some trace of Fe, W and Ni elements dissolution. Insights on the photooxidation performance of nanostructured FeWO4 provide promising directions for the engineering of small band‐gap catalysts for a variety of photoelectrochemical applications.
Ultrastretchable Triboelectric Nanogenerators Based on Ecoflex/Porous Carbon for Self‐Powered Gesture Recognition
Authors: Zhao Jiang , Xiao Yu , Yang Wei , Zhang Shaochun , Wang Huining , Wang Qiang , Sun Zhaoyang , Li Wenjie , Gao Min , Wang Zefeng , Xu Yun , Chen Huamin , Wang Jun
Published: January 2023

Stretchable triboelectric nanogenerator (STENG) has become the research hotspots in flexible power supply, which is indispensable in intelligent wearable electronics. In this work, an ultrastretchable Ecoflex/porous carbon‐based STENG (EP‐STENG) is presented for gesture recognition application. Due to the ultrahigh stretchability of Ecoflex (570%) and high conductivity of porous carbon, the EP thin film acts as an excellent stretchable electrode under various deformations. In addition, the output performance of the EP‐STENG can be enhanced by adjusting the concentration of porous carbon. At a mass fraction of 0.28 wt%, the EP‐STENG reaches the optimal output performance. This is due to the appropriate conductive networks and strong trapping effect. Surprisingly, the performance of the EP‐STENG still remains 70% at a stretching strain of 177%, which makes it a promising wearable sensor for human–machine interaction. Finally, the EP‐STENG‐based stretchable sensor array can acquire gesture signal of the fingers, which can control the mechanical hand to make corresponding actions. The proposed ultrastretchable EP‐STENG can promote the development of intelligent wearable system and flexible electronics.
Molecular Copper Phthalocyanine and FeOOH Modified BiVO4 Photoanodes for Enhanced Photoelectrochemical Water Oxidation
Authors: Fan Mengmeng , Tao Ziyang , Zhao Qiang , Li Jinping , Liu Guang , Zhao Chuan
Published: January 2023

The limited performance of BiVO4 for photoelectrochemical (PEC) water splitting is currently restricted to limited light absorption and rapid carrier recombination. Herein, molecular copper phthalocyanine (CuPc) and FeOOH co‐integrated BiVO4 photoanode are prepared by a simple dipping method and demonstrate significantly improved PEC water oxidation activities. The optimized BiVO4/CuPc/FeOOH photoanode attains a photocurrent density of 3.67 mA cm−2 at 1.23 VRHE and maintains the PEC performance without significant decay over a long period of time. In addition, significant increase of charge separation efficiency and decrease of charge transfer resistance of the BiVO4/CuPc/FeOOH photoanode also demonstrate that the hole–electron transfer and water oxidation reaction are promoted. It is found that CuPc has a similar structure to photosensitized chlorophyll, which can broaden the absorption range of BiVO4 in the visible region and improve the photo‐generated carriers transfer in the semiconductor. Whereas the FeOOH layer can rapidly transfer the photo‐generated holes into the electrolyte to participate in the water oxidation reaction as oxygen evolution cocatalyst. This work provides a feasible pathway to improve the PEC water splitting performance of BiVO4 by increasing light absorption and accelerating carrier transfer.
Accelerated Multi‐Stage Synthesis of Indium Phosphide Quantum Dots in Modular Flow Reactors
Authors: Epps Robert W. , Delgado‐Licona Fernando , Yang Hyeyeon , Kim Taekhoon , Volk Amanda A. , Han Suyong , Jun Shinae , Abolhasani Milad
Published: January 2023

Development and scalable nanomanufacturing of high‐quality heavy metal‐free quantum dots (QDs) with high‐dimensional experimental design spaces still remain a challenge. In this work, a universal flow chemistry framework for accelerated fundamental and applied studies of heavy metal‐free QDs with multi‐stage chemistries is presented. By introducing flexible time‐ and temperature‐to‐distance transformation using modular fluidic blocks, an in‐flow synthetic route of InP QDs with the highest reported first excitonic absorption peak to valley ratio is unveiled  with a reaction time one order of magnitude faster than batch reactors. The flexible time‐ and temperature‐to‐distance transformation as an enabling factor for generalization of flow reactors toward the accelerated discovery, development, and nanomanufacturing of high‐quality emerging nanomaterials for next‐generation energy, display, and chemical technologies is discussed.
Thiol‐ene‐Based 3D Printing of Bioresorbable Fumarate‐Based ABA Triblock Copolyester Elastomers
Authors: Yeazel‐Klein Taylor Rae , Davis Anna Gray , Becker Matthew Leonard
Published: January 2023

Additive manufacturing continues to evolve as a powerful tool for the fabrication of tissue‐engineered scaffolds and medical devices. With this evolution, a library of materials with a broad range of mechanical properties and degradation behaviors is needed. Photochemically crosslinked polymeric systems typically possess a network of covalent bonds which limit their degradability and serve to hinder the clinical translation of medical devices made from these materials. In this work, the use of ABA triblock poly(propylene fumarate‐b‐γ‐methyl‐ε‐caprolactone‐b‐propylene fumarate) copolymers coupled with a degradable, thiol‐based crosslinking system on a continuous liquid interface production (CLIP) digital light processing (DLP) 3D printer is reported. The printed elastomeric structures experience a range of mechanical behaviors (strain at failure spanning from 55% to 290%) and degradation behavior that is dependent on the stoichiometry of the individual blocks within the ABA copolymer and the alkene‐to‐thiol crosslinking ratios.
Wearable Platform for Low‐Dose Inhaled Nitric Oxide Therapy
Authors: Mazur Federico , Lisi Fabio , Ma Zhipeng , Chandrawati Rona
Published: January 2023

The ongoing COVID‐19 pandemic has been a daunting challenge for healthcare systems worldwide. The World Health Organization has recommended various measures to reduce or limit the spread of the virus, one of which includes the use of face masks. This increase in their demand has provided a unique opportunity to improve the technology by offering, in addition to their inherent protection, therapeutic benefits. One such benefit involves inhaled nitric oxide (iNO) therapy. iNO has proven to be a beneficial therapeutic in patients with acute, hypoxemic respiratory failure and lung injury. Specifically, its potential application stems from its ability to rapidly increase oxygen partial pressure in arterial blood. However, iNO treatments generally require pressurized gas cylinders which are coupled with high costs and lack of portability. A face mask which can deliver therapeutic NO is developed using humidity‐triggered NO‐releasing nanoparticles. This platform can deliver a low dose of 2.1–2.5 ppm NO for 90 min in a sustained manner. Moreover, it can be stored for extended periods of time and can be easily transported due to its light weight. This NO mask has the potential to alleviate the strain that affects financially limited healthcare systems in developing regions.
Direct Writing of Liquid Metal onto an Electrospun Graphene Oxide Composite Polymer Nanofiber Membrane for Robust and Stretchable Electrodes
Authors: Wu Yi‐Gen , Wang Zhong‐Bao , Xu Jin‐Bin , Chen Zhuo , Zeng Guo‐Long , Xu Zhen‐Jin , Zhou Jia‐Hong , Chen Xin‐Qi , Tan Qiu‐Lin , Chen Qin‐Nan , Yang Yang , Chen Song‐Yue , Wang Ling‐Yun , Wu De‐Zhi
Published: January 2023

Highly stretchable electrodes with electrically robust behavior are critical for wide applications of soft robots, electronic skins, and flexible sensors. However, it remains challenging to fabricate such electrodes with traditional fabrication methods, such as lithography, conductive composite material synthetization, stencil printing, and microchannel injection. Herein, a facile method is proposed to construct robust and stretchable electrodes by direct‐written liquid metal (LM) onto a predeposited interface bonding layer, which greatly improves the interfacial force between the LM and substrate. An electrospun graphene oxide/thermoplastic polyurethane composite nanofiber membrane is used as the bonding layer, which provides rich –OH on the interface and in situ forming of hydrogen bond (H‐bond) with the LM oxide layer. A prototype electrode shows stretchability of 580%. The resistance remains stable that varies from 2.8 to 19.3 Ω at 500% elongation, and varies slightly after 7500 stretching cycles under 50% elongation, from 2.6–4.0 to 4.4–6.4 Ω. The fabrication technique is demonstrated with applications in stretchable circuit board assemblies and stretchable electronic cables, indicating a potential effective method for fabricating high‐performance stretchable electrodes.