Ultrathin and flexible electromagnetic shielding materials hold great potential in civil and military applications.Despite tremendous research efforts,the development of advanced shielding materials is still needed to...Ultrathin and flexible electromagnetic shielding materials hold great potential in civil and military applications.Despite tremendous research efforts,the development of advanced shielding materials is still needed to provide additional functionalities for various artificial-intelligence-driven systems,such as tactile sensing ability.Herein,a layering design strategy is proposed to fabricate ultrathin Ti_(3)C_(2)T_(x)MXene-aramid nanofiber(MA)films by a layer-by-layer assembling process.Compared to that of randomly mixed films,the designed MA films exhibited a higher EMI shielding efficiency at an ultrathin thickness of 9 pm,which increased from 26.4 to 40.7 dB,owing to the additional multiple-interface scattering mechanism.Importantly,the novel MA films displayed strong EMI shielding ability even after heating/cooling treatments within a wide temperature range of-196 to 300℃.Moreover,the same material displayed a tensile strength of 124.1±2.7 MPa and a toughness of 6.3±1.1 MJ·m^(-3),which are approximately 9.1 times and 45 times higher than those of pure MXene films,respectively.The MA film is also capable of detecting tactile signals via the triboelectric effect.A 2×4 tactile sensor array was developed to achieve an accurate signal catching capability.Therefore,in addition to the shielding performance,the manifestation of tactile perception by the MA films offers exciting opportunities in the fields of soft robotics and human-machine interactions.展开更多
We demonstrate an ultralow-noise single-photon detection system based on a sensitive photomultiplier tube（PMT） with precise temperature control, which can capture fast single photons with intervals around 10 ns.By i...We demonstrate an ultralow-noise single-photon detection system based on a sensitive photomultiplier tube（PMT） with precise temperature control, which can capture fast single photons with intervals around 10 ns.By improvement of the electromagnetic shielding and introduction of the self-differencing method, the dark counts（DCs） are cut down to ~1%. We further develop an ultra-stable PMT cooling subsystem and observe that the DC goes down by a factor of 3.9 each time the temperature drops 10°C. At -20°C it is reduced 400 times with respect to the room temperature（25°C）, that is, it becomes only 2 counts per second, which is on par with the superconducting nanowire detectors. Meanwhile, despite a 50% loss, the detection efficiency is still 13%. Our detector is available for ultra-precise single-photon detection in environments with strong electromagnetic disturbances.展开更多
利用化学镀方法在桦木单板表面沉积Ni—Cu—P三元合金,考查施镀温度对镀后单板表面电阻率和电磁屏蔽效能的影响,采用扫描电镜(SEM)观察镀后单板的表面形貌,利用EDS和XPS分析镀层成分,利用X射线衍射(XRD)分析镀层的组织结构,采用直拉法...利用化学镀方法在桦木单板表面沉积Ni—Cu—P三元合金,考查施镀温度对镀后单板表面电阻率和电磁屏蔽效能的影响,采用扫描电镜(SEM)观察镀后单板的表面形貌,利用EDS和XPS分析镀层成分,利用X射线衍射(XRD)分析镀层的组织结构,采用直拉法测定镀层与木材表面的结合强度。结果表明:当温度从80℃升高到90℃时,镀层平均表面电阻率从0.451Ω/cm2降低至0.301Ω/cm2;继续升高温度,表面电阻率小幅升高;在90℃时,施镀单板的电磁屏蔽效能在9 k Hz^1.5 GHz频段达到55~60 d B。SEM观察发现镀层连续、致密且具有金属光泽;EDS分析可知镀层中存在Ni、Cu和P元素,XPS分析可知镀层组成为Ni、Cu、P,其质量分数分别为79.84%、11.82%和8.34%;XRD分析表明镀层为微晶态结构;镀层与木材表面结合牢固。展开更多
基金supported by the National Natural Science Foundation of China(No.51877132).
文摘Ultrathin and flexible electromagnetic shielding materials hold great potential in civil and military applications.Despite tremendous research efforts,the development of advanced shielding materials is still needed to provide additional functionalities for various artificial-intelligence-driven systems,such as tactile sensing ability.Herein,a layering design strategy is proposed to fabricate ultrathin Ti_(3)C_(2)T_(x)MXene-aramid nanofiber(MA)films by a layer-by-layer assembling process.Compared to that of randomly mixed films,the designed MA films exhibited a higher EMI shielding efficiency at an ultrathin thickness of 9 pm,which increased from 26.4 to 40.7 dB,owing to the additional multiple-interface scattering mechanism.Importantly,the novel MA films displayed strong EMI shielding ability even after heating/cooling treatments within a wide temperature range of-196 to 300℃.Moreover,the same material displayed a tensile strength of 124.1±2.7 MPa and a toughness of 6.3±1.1 MJ·m^(-3),which are approximately 9.1 times and 45 times higher than those of pure MXene films,respectively.The MA film is also capable of detecting tactile signals via the triboelectric effect.A 2×4 tactile sensor array was developed to achieve an accurate signal catching capability.Therefore,in addition to the shielding performance,the manifestation of tactile perception by the MA films offers exciting opportunities in the fields of soft robotics and human-machine interactions.
基金supported by the National Natural Science Foundation of China(Nos.11574026 and 11274037)the Program for New Century Excellent Talents in University,MOE of China(No.NCET-12-0765)the Foundation for the Author of National Excellent Doctoral Dissertation,China(No.201236)
文摘We demonstrate an ultralow-noise single-photon detection system based on a sensitive photomultiplier tube（PMT） with precise temperature control, which can capture fast single photons with intervals around 10 ns.By improvement of the electromagnetic shielding and introduction of the self-differencing method, the dark counts（DCs） are cut down to ~1%. We further develop an ultra-stable PMT cooling subsystem and observe that the DC goes down by a factor of 3.9 each time the temperature drops 10°C. At -20°C it is reduced 400 times with respect to the room temperature（25°C）, that is, it becomes only 2 counts per second, which is on par with the superconducting nanowire detectors. Meanwhile, despite a 50% loss, the detection efficiency is still 13%. Our detector is available for ultra-precise single-photon detection in environments with strong electromagnetic disturbances.
文摘利用化学镀方法在桦木单板表面沉积Ni—Cu—P三元合金,考查施镀温度对镀后单板表面电阻率和电磁屏蔽效能的影响,采用扫描电镜(SEM)观察镀后单板的表面形貌,利用EDS和XPS分析镀层成分,利用X射线衍射(XRD)分析镀层的组织结构,采用直拉法测定镀层与木材表面的结合强度。结果表明:当温度从80℃升高到90℃时,镀层平均表面电阻率从0.451Ω/cm2降低至0.301Ω/cm2;继续升高温度,表面电阻率小幅升高;在90℃时,施镀单板的电磁屏蔽效能在9 k Hz^1.5 GHz频段达到55~60 d B。SEM观察发现镀层连续、致密且具有金属光泽;EDS分析可知镀层中存在Ni、Cu和P元素,XPS分析可知镀层组成为Ni、Cu、P,其质量分数分别为79.84%、11.82%和8.34%;XRD分析表明镀层为微晶态结构;镀层与木材表面结合牢固。
