COMBUSTION AND FLAME
·
2021
·
IF 4.185
Chun Zhang,Huiqing Mao,Rui Cui,Xiandie Zhang,Jing Yang,Jie Ji,Xiang Zhou
High content of active component, low electrostatic sensitivity and superior long-term storage stability endow n-Si powder unique advantages for application in nanoenergetic composites. In this study, hydrophobic and corrosion-resistant Si@PVDF nanostructured energetic films with different stoichiometric ratios are successfully prepared by electrospinning technique . The energetic characteristics are systematically investigated in terms of thermal analysis, open-air combustion and constant-volume combustion. The results show that Si@PVDF films are microscopically composed of fibers with diameters of about 200–300 nm. With the increase of stoichiometric ratio, more and more n-Si aggregates are found on the surface of fibers. When Si@PVDF is stored in deionized water (50 °C) or NaOH solution (50 °C, 3 mol/L) for 72 h, around 100% and 73.3% of n-Si is retained. Si@PVDF can be thermally ignited, with appreciable heat and pressure output, and the combustion behaviors are strongly affected by the stoichiometric ratio and the environmental conditions. As a comparison, physically mixed Si/PVDF cannot maintain a self-sustained combustion. Through the coupled thermal analysis and mass spectrometry analysis, combined with the morphological and structural characterization of the solid residues , the reaction mechanism of Si@PVDF at a low heating rate is preliminarily obtained.
研究领域:
材料科学
·
能源材料
·
燃烧化学
✓ 已验证
DOI
高影响因子
ACS Applied Polymer Materials
·
2024
·
IF 4.4
Zhao-Lei Huo,Jia-Yu Qiao,Le-Xi Zhang,Yao-Wen Yue,Qi-Da Qiu,Zhi-Jiang Hou,Jing Yin,Li-Jian Bie
Nowadays, attractive progress has been made on flexible humidity sensors for multifunctional applications, yet most of them still suffer from intrinsic instability due to the device structure based on flexible substrates. Herein, high-performance flexible humidity sensors were constructed using alkali metal halide doped polyvinylpyrrolidone (PVP)/polyvinylidene fluoride (PVDF) freestanding films. These films are prepared via a versatile thermally induced phase separation procedure with a network-like porous structure. After doping with metal salts of MCl (M = Li, Na, K), the humidity sensing performance is highly improved, among which the LiCl@PVP/PVDF film is the optimized one. In the relative humidity range of 11–97% at room temperature, the LiCl@PVP/PVDF sensor exhibits high response (2.3 × 103), fast response (10 s), small hysteresis (0.41%), and excellent repeatability. Notably, the LiCl@PVP/PVDF film is featured as fully self-supporting without the assistance of any substrate, readily tailorable that can be cut into different shapes, as well as highly flexible that can be bent to certain angles, and meanwhile almost maintains its response without significant decrease. Furthermore, the excellent performance enables the LiCl@PVP/PVDF sensor to demonstrate great potential in real-time noncontact diaper and finger detection. This contribution provides a practical humidity sensing candidate for moisture monitoring and gives insights into the fields of humidity sensors and flexible electronics.
研究领域:
材料科学
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传感器技术
·
电子工程
✓ 已验证
产品关联
DOI
高影响因子
Advanced Materials Technologies
·
2023
·Vol. 8
·期 7
·2201535
·
IF 6.8
Jieyu Dai,Jianping Meng,Xiaoming Zhao,Weiyi Zhang,Yubo Fan,Bojing Shi,Zhou Li
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.
研究领域:
生物医学工程
·
材料科学
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传感器技术
✓ 已验证
产品关联
DOI
高影响因子
ACS Applied Materials & Interfaces
·
2021
·
IF 9.229
Zebang Luo,Jing Chen,Zhengfang Zhu,Lin Li,Yi Su,Wei Tang,Olatunji Mumini Omisore,Lei Wang,Hui Li
Flexible pressure sensors have attracted increasing attention because they can mimic human skin to sense external pressure; however, for mimicking human skin, the sensing of a pressure point is far from sufficient. To realize fully biomimetic skins, it is crucial for flexible sensors to have high resolution and high sensitivity. We conducted simulations and experiments to determine the relationship between the sensor sensitivity and physical parameters, such as the effective relative permittivity and air ratio of the dielectric layer. According to the results, a micropillar–poly(vinylidene fluoride) (PVDF) dielectric layer was designed to achieve high sensitivity (0.43 kPa–1) in the low-pressure regime (<1 kPa). An 8 × 8 pixel sensor matrix was prepared based on a micropillar–PVDF (MP) film and electrode array (MPEA) to detect the pressure distribution with high resolution (13 dpi). Each pixel could reflect the point of applied pressure through an obvious change in the relative capacitance; moreover, objects with various geometries could be mapped by the pixels of the flexible sensor. A counterweight, a plastic flag, and pine leaves were placed on the flexible sensor, and the shapes were successfully mapped; in particular, the mapping of the ∼0.005 g ultra-lightweight pine leaves with a length of 7 mm and a width of 0.6 mm shows the high sensitivity and high resolution of our flexible pressure sensor.
研究领域:
材料科学
·
传感器技术
✓ 已验证
产品关联
DOI
PubMed
高影响因子
Materials
·
2022
·Vol. 15
·期 15
·5191
·
IF 3.748
Qiupeng Wu,Zhiheng Yu,Fengli Huang,Jinmei Gu
Triboelectric nanogenerators (TENGs) are considered to be the most promising energy supply equipment for wearable devices, due to their excellent portability and good mechanical properties. Nevertheless, low power generation efficiency, high fabrication difficulty, and poor wearability hinder their application in the wearable field. In this work, PA66/graphene fiber films with 0, 1 wt%, 1.5 wt%, 2 wt%, 2.5 wt% graphene and PVDF films were prepared by electrospinning. Meanwhile, TENGs were prepared with PA66/graphene fiber films, PVDF films and plain weave conductive cloth, which were used as the positive friction layer, negative friction layer and the flexible substrate, respectively. The results demonstrated that TENGs prepared by PA66/graphene fiber films with 2 wt% grapheme showed the best performance, and that the maximum open circuit voltage and short circuit current of TENGs could reach 180 V and 7.8 μA, respectively, and that the power density was 2.67 W/m2when the external load was 113 MΩ. This is why the PA66/graphene film produced a more subtle secondary network with the addition of graphene, used as a charge capture site to increase its surface charge. Additionally, all the layered structures of TENGs were composed of breathable electrospun films and plain conductive cloth, with water vapor transmittance (WVT) of 9.6 Kgm−2d−1, reflecting excellent wearing comfort. The study showed that TENGs, based on all electrospinning, have great potential in the field of wearable energy supply devices.Keywords:triboelectric nanogenerators;PA66/graphene fiber films;PVDF films;performance;wearing comfort
研究领域:
材料科学
·
纳米技术
·
能源技术
·
可穿戴设备
✓ 已验证
DOI
PubMed
高影响因子
ADVANCED FUNCTIONAL MATERIALS
·
2023
·Vol. 33
·期 51
·2305531
·
IF 19
Renhou Han,Yue Liu,Yepei Mo,Huichen Xu,Zhengwen Yang,Rongrong Bao,Caofeng Pan
Flexible capacitive pressure sensors play an important role in electronic skin and human–machine interaction due to their high sensitivity and convenient preparation, comparing with those resistive/piezoresistive sensors. However, due to the complexity of the application environment, reported capacitive sensors often experience signal instability by electromagnetic interference and proximity effects. The great challenge for capacitive sensors is to maintain sensitivity and wide linear range while reducing interference. This study proposes a high anti-jamming capacitive flexible pressure sensor with polyvinylidene fluoride (PVDF)@AgNWs@TiO 2 film as the dielectric layer. Core–shell structure-based AgNWs@TiO 2 is embedded into the PVDF film. The introduction of the core–shell structure not only enhances the initial capacitance but also balances the dielectric constant, dielectric loss, and breakdown strength of the dielectric layer. The sensor is validated to exhibit a high signal-to-noise ratio for a variety of interference sources and is demonstrated with an intelligent glove sensing system, which provides a new idea for developing a high anti-jamming capacitive flexible pressure sensor.
研究领域:
材料科学
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电子皮肤技术
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人机交互
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF ELECTRONIC MATERIALS
·
2023
·Vol. 53
·期 4
·2076-2083
·
IF 2.1
Chen Caifeng,Liu Kai,Zhong Wuwen,Guo Junhao,Tang Xinting,Wang Andong
High β-phase polyvinylidene fluoride (PVDF) thin films have excellent piezoelectricity and flexibility. They are widely used in wearable devices, hydroacoustic ultrasound, and energy harvesting. The preparation of PVDF thin films by near-electric-field 3D printing can be customized in shape, and the high β-phase can be obtained without stretching or polarization. In this work, the effects of polar solvent, printing voltage, and PVDF molecules on the β-phase content of PVDF thin films prepared by near-electric-field 3D printing were analyzed. The results show that the polarity of the solvent affects the molecular chain conformation of PVDF, which is favorable for the generation of the β-phase. With the increase of solvent polarity, the β-phase content in PVDF films increased from 21.40% to 26.31%. The mutual motion of the collecting plate and the needle will produce stronger mechanical traction on the PVDF fibers, which is due to the smaller diameter of the PVDF fibers caused by the high printing voltage. The joint action of this tensile force and the strong electric field attraction promotes the β-phase transition. When the printing voltage is 8 kV, the F (β) value of PVDF film is increased by 47.37% over that without applied voltage. In addition, the interaction of small and large PVDF molecular weight will also result in mechanical deformation of the molecular chain and promote the β-phase transition.
研究领域:
材料科学
·
高分子科学
·
3D打印技术
·
静电学
✓ 已验证
DOI
高影响因子
Journal of Materials Chemistry A
·
2024
·
IF 10.7
Ying Luo,Da Lei,Maohua Li,Yuansheng Ge,Jiguang Li,Baiyi Zu,Jun Yao,Xincun Dou
Metal organic frameworks (MOFs) have made great progress in the field of fluorescent sensing; however, whether the electronic structure and recognized sites can be adjusted by external functionalization still remains challenging. Here, by postmodifying 5-carboxyfluorescein (Flu), externally coupled orbitals were introduced into the electronic structure of UiO-66-OH, and thus an effective photo-induced energy transfer (PET) process was established in functionalized MOFs (UiO-66-Flu), resulting in the reduction of the intrinsic blue fluorescence. Due to the formation of the ester bond by effective incorporation of the surface –OH with Flu, the hydrazinolysis reaction triggered by hydrazine could happen and the Zr6O6 clusters could further reduce the reaction energy barrier through strong hydrogen bonding with hydrazine, resulting in a remarkably low limit of detection (LOD, 27.17 nM) and a fast response (4 s). Furthermore, with polyvinylidene fluoride (PVDF) as the dispersion medium, UiO-66-Flu was fabricated into a UiO-66-Flu/PVDF film sensor, enabling the rapid detection of gaseous hydrazine within 2 s in simulated practical scenarios. We expect that the present fluorescent ligand modifying concept will not only deepen the understanding of electronic structure engineering in functionalized MOF design, but also shine light on the exploration of high-performance MOF-based sensing strategies.
研究领域:
材料科学
·
化学工程
·
分析化学
·
传感器与执行器
✓ 已验证
产品关联
DOI
高影响因子
SENSORS AND ACTUATORS A-PHYSICAL
·
2024
·
IF 4.1
Yufei Zhai,Song Li,Yuxuan Dong,Ying Jin,Xuanzheng Zhou,Min Wang
A luminescence quenching enhanced infrared (IR) detector has been developed to achieve highly sensitive recognition of human body by adding metallic luminescence quenchers. Spherical Ag NPs were mixed with Ru(phen) 3 2+ complex to obtain temperature-sensitive Ag/Ruphen/PVDF films. The relationships among luminescence output, temperature rise and silver addition were investigated and a satisfactory combination of enhanced luminescence factor and temperature change was found with an addition of 5 mol% of 71 nm Ag NPs. It is found that the metal-enhanced luminescence output is insignificant compared to its thermal ingredient since silver provides additional possible electron transfer channels, promoting non-radiative transitions and weakening luminescence. Besides, the Ag NPs induced additional temperature rise bringing further reduction of luminescence. The photothermal effect of Ag NPs can attain a higher temperature change under a certain IR radiation without an observed degradation of luminescence output. A coupled optical-thermal model was established to explain the schematic of the constructed infrared thermal detector. The non-invasive detections of moving and stationary human by the detector were successfully demonstrated. The work tends to provide an engineered optical-thermal model in luminophores and construct highly sensitive luminescence-based infrared thermal detectors.
研究领域:
材料科学
·
纳米技术
·
光学
·
传感器
✓ 已验证
产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）