Probing Nanoscale Coassembly with Dual Mechanochromic Sensors

Attractive electrostatic forces between polymers can be exploited to create well‐defined and responsive nanoscale structures. In the process of charge‐driven coassembly, the polymers involved undergo subtle conformational changes. However, ascertaining these conformational transitions, and relating this to the nanostructures that are formed, has remained elusive to date. Here it is shown how the force‐optical response of tailored mechanochromic polymers can be used to detect structural transitions that occur at the nanoscale during assembly. It is shown that at low‐charge stoichiometry, electrostatic binding causes individual macromolecules to stretch and stiffen. Remarkably, at stoichiometries close to full charge compensation a gradual transition from single molecular complexes to multimolecular micelles is observed. Moreover, the same macromolecular sensors reveal how the assembly pathways are fully reversible as the binding strength is weakened. These results highlight how mechanochromic polymer sensors can be used to detect the molecular transitions occur during supramolecular structure formation with high precision.     

Mechanochromic and Thermochromic Sensors Based on Graphene Infused Polymer Opals

High quality opal‐like photonic crystals containing graphene are fabricated using evaporation‐driven self‐assembly of soft polymer colloids. A miniscule amount of pristine graphene within a colloidal crystal lattice results in the formation of colloidal crystals with a strong angle‐dependent structural color and a stop band that can be reversibly shifted across the visible spectrum. The crystals can be mechanically deformed or can reversibly change color as a function of their temperature, hence their sensitive mechanochromic and thermochromic response make them attractive candidates for a wide range of visual sensing applications. In particular, it is shown that the crystals are excellent candidates for visual strain sensors or integrated time‐temperature indicators which act over large temperature windows. Given the versatility of these crystals, this method represents a simple, inexpensive, and scalable approach to produce multifunctional graphene infused synthetic opals and opens up exciting applications for novel solution‐processable nanomaterial based photonics.     

Elastoplastic Inverse Opals as Power‐Free Mechanochromic Sensors for Force Recording

Light‐weight, power‐free mechanochromic sensors that can change and record the reflective color depending on the magnitude and rate of the applied force are fabricated from inverse opals by infiltrating the colloidal crystals of silica particles with uncrosslinked SU‐8, followed by removal of the colloidal templates. The mechanical sensing range of the materials is high, 17.6–20.4 MPa. Due to elastoplastic deformation of the SU‐8 films, the deformed structures and thus colors can be locked after the removal of the load, therefore establishing a quantitative relationship between the mechanical force and optical responses. In comparison, mechanochromic photonic gels reported in the literature typically detect force in the range of 10–100 kPa; once the load is removed, the structure and color return back to the original ones. The mechanochromic sensors are highly sensitive: the ratio of shift in the stopband wavelength to the change in applied strain is up to 5.7 nm per percent, the highest among literature. Comparison of finite element simulations with experiments confirms the elastoplastic deformation of the films and highlights that reconfiguration of pore shape under compression plays a key role in the mechanochromic response.     

Mechanochromic Photonic Vitrimer Thermal Management Device Based on Dynamic Covalent Bond

Flexible self-healing thermal management devices are increasingly in demand due to their high flexibility, low driving voltage, and excellent stability of thermal property. In this paper, the design of mechanochromic self-healing thermal management devices is reported based on photonic vitrimer through self-healing dynamic covalent bond. A series of new photonic vitrimers i first prepared by dynamic disulfide covalent bond and PS@SiO₂ photonic crystals. The resulting photonic vitrimer exhibits bright structural colors, large tensile strain (>1000%), high mechanical strength (>10 MPa) and self-healing ability (>95% efficiency). More importantly, the structural color remains constant after 10000 stretching/releasing cycles, demonstrating excellent mechanical stability, creep-resistance, and durability. Taking advantage of the above features, a novel mechanochromic flexible wireless thermal management (MFW) device is developed by semi-embedding the photonic vitrimer in a thermally conductive carbon nanotube film and then integrating it with a Bluetooth module and a control chip. Interestingly, the MFW device exhibits mechanochromic property, fast thermal response, low driving voltage (103 °C, at 3 V), and precise temperature control. Notably, the device even remains electrothermal performance (105 °C) after self-healing. This work provides new insight into the self-healing photonic materials, and the device shows promising applications in wearable electronics, vitro physiotherapy, and personal heating.     

传感器

能滤除假回波的超声液位计；能测量多种气体的瞬态分析仪；通孔式加速度计；法兰安装式扭矩变送器；基于微处理器的指示器／调节器。     

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硫化氯分析仪;防堵塞型液位计;区域视觉传感器;带数字编程功能的超声传感器;基于USB接口的倾角传感器。[编者按]     

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采用增强型像素结构的CMOS图像传感器;可用在极恶劣环境下的不锈钢视觉传感器;全集成200万像素CMOS图像传感器.     

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传感器

小型化激光导航传感器；工业标准的高精度数字温度传感器系列；     

传感器

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