With the prosperous development of artificial intelligence,medical diagnosis and electronic skins,wearable electronic devices have drawn much attention in our daily life.Flexible pressure sensors based on carbon mater...With the prosperous development of artificial intelligence,medical diagnosis and electronic skins,wearable electronic devices have drawn much attention in our daily life.Flexible pressure sensors based on carbon materials with ultrahigh sensitivity,especially in a large pressure range regime are highly required in wearable applications.In this work,graphene membrane with a layer-by-layer structure has been successfully fabricated via a facile self-assembly and air-drying(SAAD)method.In the SAAD process,air-drying the self-assembled graphene hydrogels contributes to the uniform and compact layer structure in the obtained membranes.Owing to the excellent mechanical and electrical properties of graphene,the pressure sensor constructed by several layers of membranes exhibits high sensitivity(52.36 kPa……-1)and repeatability(short response and recovery time)in the loading pressure range of 0–50 kPa.Compared with most reported graphene-related pressure sensors,our device shows better sensitivity and wider applied pressure range.What’s more,we demonstrate it shows desired results in wearable applications for pulse monitoring,breathing detection as well as different intense motion recording such as walk,run and squat.It’s hoped that the facilely prepared layer-by-layer graphene membrane-based pressure sensors will have more potential to be used for smart wearable devices in the future.展开更多
Considered in this paper are the factors influencing sensitivity of analytical devices based on surface plasmon resonance phenomenon. The decrease in temperature influence on sensitivity of these devices can be reache...Considered in this paper are the factors influencing sensitivity of analytical devices based on surface plasmon resonance phenomenon. The decrease in temperature influence on sensitivity of these devices can be reached using thermo stabilization of the whole device with flow cells for studied substances. Adduced here are some results concerning the influence of deposition geometry for nano-dimensional gold layer covering the surface of operating element on sensitivity of these devices.展开更多
Hydrazine hydrate(DH)is an important fine chemical intermediate and as fuel for rockets,however,it also has serious toxic for humans and environment.Developing novel materials and methods for sensitive detection of DH...Hydrazine hydrate(DH)is an important fine chemical intermediate and as fuel for rockets,however,it also has serious toxic for humans and environment.Developing novel materials and methods for sensitive detection of DH in water and air is an important task.In order to effectively detect DH,a novel conductive supramolecular polymer metallogel(PQ-Ag)has been constructed by the coordination of bis-5-hydroxyquinoline functionalized pillar[5]arene(PQ5)with Ag+.The metallogel PQ-Ag could realize the multi-channel sensitive detection of DH through naked-eye,fluorescence,and electrochemical methods.The lowest limit of detection(LOD)is 0.1 mg/m^(3)in air and 2.68×10^(−8)mol/L in water,which is lower than the standard of the US Environmental Protection Agency(EPA)for DH of maximum allowable concentration in drinking water.More importantly,an electronic device for DH detection based on the metallogel PQ-Ag was designed and prepared,which can realize conveniently and efficiently multi-channel detection and alert of DH through sound and light alarms not only in water but also in air.展开更多
To optimize the performance of a thermoelectric device for a specific application, the device should be uniquely designed for the application. Achieving an optimum design requires accurate measurements and credible an...To optimize the performance of a thermoelectric device for a specific application, the device should be uniquely designed for the application. Achieving an optimum design requires accurate measurements and credible analysis to evaluate the performance of the device and its relationship with the device parameters. To do that, we designed, fabricated, and tested four devices based on Bi2Te3 and Sb2Te3. To evaluate the accuracy of our analysis, experimental measurements were compared with the numerical simulation performed using COMSOLTM. The two sets of results were found to be in full agreement. This is a proof of the accuracy of our experimental measurements and the credibility of our simulation. The study shows that testing or simulating the devices without heat sink will lead to skewed results. This is because the junction will not hold its temperatures value, but will, instead, automatically change its value to the direction of thermal equilibrium. The study shows also that there is no reciprocity between the input and the output characteristics of the devices. Therefore, a device optimized for cooling and heating may not be automatically optimized for energy harvesting. For heating and cooling, temperature sensitivity should be optimized;while for energy harvesting, voltage sensitivity should be optimized. Using heat sink, our devices achieved a voltage sensitivity of 187.77 μV/K and a temperature sensitivity of 6.12 K/mV.展开更多
Micro thermoelectric device(μ-TED)emerges with great attention in energy generation,thermal management,and heat sensing applications.However,the large sensitive area is necessary to accommodate enough thermoelectric ...Micro thermoelectric device(μ-TED)emerges with great attention in energy generation,thermal management,and heat sensing applications.However,the large sensitive area is necessary to accommodate enough thermoelectric couples(TCs)for a high thermoelectric performance.This limits the potential in micro energy harvesting and ultrasensitive sensing applications.Here,we adopted an optimized MEMS-based process to fabricate the ultra-sensitive micro-thermoelectric device(μ-TED).With the help of MEMS-compatible electrochemical deposition,the small size(25μm),high aspect ratio(1:1.25),and alternating distributed P/N structures are achieved.As a result,theμ-TED realizes an ultra-high integration density of 19,900 thermoelectric couples per cm2.Moreover,it shows a great thermoelectric sensitivity of 212 mV/(K·cm2)and a competitive power factor of 0.51μW/(K2·cm2),which means theμ-TED is competent for miniaturized applications.Additionally,theμ-TED shows an ultra-low detection limit of 5 mm/s and a short response time of 100 ms,revealing great potential in fast detections of the ultra-low airflow.Furthermore,the ultra-sensitiveμ-TED is utilized as a flexible breath sensor,due to its compact size.The breath signal of different motion states is successfully detected.These results confirm that the ultra-sensitiveμ-TED holds outstanding potential for ultra-sensitive airflow sensing and energy harvesting devices.展开更多
玄武岩纤维增强复合材料(basalt fiber-reinforced polymer,BFRP)具有优异的力学性能和可熔融再生特性,在汽车轻量化领域的应用前景广阔。针对某车型的铝制防撞装置,开展BFRP/铝混合防撞装置的多目标优化设计。首先,对BFRP层合板开展力...玄武岩纤维增强复合材料(basalt fiber-reinforced polymer,BFRP)具有优异的力学性能和可熔融再生特性,在汽车轻量化领域的应用前景广阔。针对某车型的铝制防撞装置,开展BFRP/铝混合防撞装置的多目标优化设计。首先,对BFRP层合板开展力学性能测试,并利用HyperMesh软件建立防撞装置有限元模型;其次,采用拉丁超立方抽样生成代理模型的训练样本,结合敏感度分析识别关键设计参数,并通过基于加权欧式距离的空间填充采样法来提升代理模型对响应指标的预测精度;最后,以防撞装置峰值载荷、总质量及横梁最大位移最小为优化目标,运用MOPSO(multi-objective particle swarm optimization,多目标粒子群优化)算法求解Pareto前沿,并基于熵权-TOPSIS(technique for order preference by similarity to an ideal solution,逼近理想解排序法)确定最优设计参数组合。结果显示:优化后防撞装置的峰值载荷降低了36.15%,总质量减小了12.23%,显著提升了耐撞性能并实现了轻量化目标。所提出的方法可为BFRP/铝混合防撞装置的轻量化设计提供一套系统性的解决方案。展开更多
High proportion of renewable energies and the installation of power electronic devices(PEDs)pose tough challenges to the operation of power systems.In this paper,the remote coordination adjustment(RCA)of PEDs in stoch...High proportion of renewable energies and the installation of power electronic devices(PEDs)pose tough challenges to the operation of power systems.In this paper,the remote coordination adjustment(RCA)of PEDs in stochastic scenarios is studied.The steady-state model for the AC/DC system with PEDs is first established,and the alternate iteration method based on linearization(AIML)is adopted,especially for efficient deterministic power flow calculation.Then,the RCA is proposed using a modular local sensitivity method combined with AIML,which can adjust the electrical variables by diverse PEDs with high efficiency.Additionally,the probabilistic power flow calculation using the quasi-Monte Carlo method with the adaptive sampling number(ASN-QMC)is introduced to keep the balance between the computational efficiency and accuracy,as well as demonstrating the positive impact of RCA by the PEDs in stochastic scenarios.The effectiveness of the proposed RCA is validated by a series of modified IEEE test systems.展开更多
An automatic cooling device has been developed by using a temperature-sensitive magnetic fluid as the coolant. A particle image velocimetry (PIV) system was used to measure the flow velocity of the fluid inside the lo...An automatic cooling device has been developed by using a temperature-sensitive magnetic fluid as the coolant. A particle image velocimetry (PIV) system was used to measure the flow velocity of the fluid inside the loop. The efficiency of the device under varying conditions such as the heat load and the power of cooling were ex- perimentally investigated. The effect of cooperation between external magnetic field and thermal field on the performance of the device was studied. As expected, a continuous flow induced by the thermal and magnetic field was observed in the loop, where heat was transferred by the circulating magnetic fluid. The synergic effect between the magnetic field and the temperature gradient has impact on the performance of the device.展开更多
通过超薄层插入与掺杂相结合的方式,分别以激光染料DCM(4-(Dicyanomethylene)-2-methyl-6-(4-dimet-hyl-aminostyryl)-4H-pyran)、铱配合物Ir(ppy)3(tris(2-phenylpyridine)iridium)和联苯乙烯衍生物BCzVB(1,4-bis[2-(3-N-ethylcarbazor...通过超薄层插入与掺杂相结合的方式,分别以激光染料DCM(4-(Dicyanomethylene)-2-methyl-6-(4-dimet-hyl-aminostyryl)-4H-pyran)、铱配合物Ir(ppy)3(tris(2-phenylpyridine)iridium)和联苯乙烯衍生物BCzVB(1,4-bis[2-(3-N-ethylcarbazoryl)vinyl]benzene)为红色、绿色和蓝色发射体,制备了磷光敏化荧光白色有机电致发光器件(OLED).通过改变DCM超薄层在CBP:Ir(ppy)3掺杂层中的插入位置实现了白色发光,最高外量子效率为2.5%(电流效率为5.1 cd/A),最高亮度为12400 cd/m^(2),且其中一种器件在1 mA/cm^(2)的电流密度下,国际照明委员会(Commission Internationale de L'Eclairage,CIE)坐标达到了理想白光平衡点(0.33,0.33).白光的获得归因于Ir(ppy)3适合的掺杂比例和DCM适合的插入位置,较好地均衡了红、绿、蓝三基色发光比例.结果表明,通过磷光敏化荧光实现三线态激子将部分能量传递给单线态激子,可望实现高效率白色有机电致发光器件,从而降低能耗并为促进OLED的应用提供更多空间.展开更多
Efficient red organic light-emitting device consisted of a compound fluorescent-phosphor-sensitized emission layer was fabricated. A novel red fluorescent dye, 3-(dicyanomethylene)-5,5-dimethyl-1-(4-dimethylamino-styr...Efficient red organic light-emitting device consisted of a compound fluorescent-phosphor-sensitized emission layer was fabricated. A novel red fluorescent dye, 3-(dicyanomethylene)-5,5-dimethyl-1-(4-dimethylamino-styryl) cyclohexene (DCDDC), and a green phosphorescent dye, fac tris(2-phenylpyridine) iridium [Ir(ppy)3] were codoped into a host material 4,4'-N,N'-dicarbazolebiphe-nyl (CBP). By adjusting the component ratio of doping system, a series of devices with different concentration proportion of Ir(ppy)3:DCDDC were constructed. The results demonstrated that the device with 0.2 wt% DCDDC had a maximum power effi-ciency (ηp) of 2.12 lm/W at a current density of 0.1 mA/cm2, which was about 38% higher than that of conventional fluorescent device. When at a current density of 4 mA/cm2 (100 cd/m2) and 52 mA/cm2 (1000 cd/m2), the ηp percentage was about 160% and 143% higher than that of conventional device, respectively. A stable red light emission at a peak of 615 nm with Commissions Internationale de l'Eclairage coordinates near the region of (0.56, 0.42) in a wide bias range was also obtained. The improved performances were attributed to the efficient multiple-stage energy transfer from the host to the vip and the suppression of loss mechanism.展开更多
基金Financial support from the grant from the City University of Hong Kong(SRG 7004918)South China University of Technology(National Key Research and Development Program of China,No.2016YFB0302000)Shenzhen University(Ten Thousand People’s Scheme,Project No.201,810,090,052)。
文摘With the prosperous development of artificial intelligence,medical diagnosis and electronic skins,wearable electronic devices have drawn much attention in our daily life.Flexible pressure sensors based on carbon materials with ultrahigh sensitivity,especially in a large pressure range regime are highly required in wearable applications.In this work,graphene membrane with a layer-by-layer structure has been successfully fabricated via a facile self-assembly and air-drying(SAAD)method.In the SAAD process,air-drying the self-assembled graphene hydrogels contributes to the uniform and compact layer structure in the obtained membranes.Owing to the excellent mechanical and electrical properties of graphene,the pressure sensor constructed by several layers of membranes exhibits high sensitivity(52.36 kPa……-1)and repeatability(short response and recovery time)in the loading pressure range of 0–50 kPa.Compared with most reported graphene-related pressure sensors,our device shows better sensitivity and wider applied pressure range.What’s more,we demonstrate it shows desired results in wearable applications for pulse monitoring,breathing detection as well as different intense motion recording such as walk,run and squat.It’s hoped that the facilely prepared layer-by-layer graphene membrane-based pressure sensors will have more potential to be used for smart wearable devices in the future.
文摘Considered in this paper are the factors influencing sensitivity of analytical devices based on surface plasmon resonance phenomenon. The decrease in temperature influence on sensitivity of these devices can be reached using thermo stabilization of the whole device with flow cells for studied substances. Adduced here are some results concerning the influence of deposition geometry for nano-dimensional gold layer covering the surface of operating element on sensitivity of these devices.
基金supported by the National Natural Science Foundation of China(NSFC,Nos.22065031,22061039)the Top Leading Talents Project of Gansu Province,the Key R&D program of Gansu Province(No.21YF5GA066)+1 种基金Gansu Province College Industry Support Plan Project(No.2022CYZC-18)Natural Science Foundation of Gansu Province(Nos.2020-0405-JCC-630,20JR10RA088).
文摘Hydrazine hydrate(DH)is an important fine chemical intermediate and as fuel for rockets,however,it also has serious toxic for humans and environment.Developing novel materials and methods for sensitive detection of DH in water and air is an important task.In order to effectively detect DH,a novel conductive supramolecular polymer metallogel(PQ-Ag)has been constructed by the coordination of bis-5-hydroxyquinoline functionalized pillar[5]arene(PQ5)with Ag+.The metallogel PQ-Ag could realize the multi-channel sensitive detection of DH through naked-eye,fluorescence,and electrochemical methods.The lowest limit of detection(LOD)is 0.1 mg/m^(3)in air and 2.68×10^(−8)mol/L in water,which is lower than the standard of the US Environmental Protection Agency(EPA)for DH of maximum allowable concentration in drinking water.More importantly,an electronic device for DH detection based on the metallogel PQ-Ag was designed and prepared,which can realize conveniently and efficiently multi-channel detection and alert of DH through sound and light alarms not only in water but also in air.
文摘To optimize the performance of a thermoelectric device for a specific application, the device should be uniquely designed for the application. Achieving an optimum design requires accurate measurements and credible analysis to evaluate the performance of the device and its relationship with the device parameters. To do that, we designed, fabricated, and tested four devices based on Bi2Te3 and Sb2Te3. To evaluate the accuracy of our analysis, experimental measurements were compared with the numerical simulation performed using COMSOLTM. The two sets of results were found to be in full agreement. This is a proof of the accuracy of our experimental measurements and the credibility of our simulation. The study shows that testing or simulating the devices without heat sink will lead to skewed results. This is because the junction will not hold its temperatures value, but will, instead, automatically change its value to the direction of thermal equilibrium. The study shows also that there is no reciprocity between the input and the output characteristics of the devices. Therefore, a device optimized for cooling and heating may not be automatically optimized for energy harvesting. For heating and cooling, temperature sensitivity should be optimized;while for energy harvesting, voltage sensitivity should be optimized. Using heat sink, our devices achieved a voltage sensitivity of 187.77 μV/K and a temperature sensitivity of 6.12 K/mV.
基金supported by the Project(NO.62502010320)the National Key Research and Development Program of China(2020YFB2009102).
文摘Micro thermoelectric device(μ-TED)emerges with great attention in energy generation,thermal management,and heat sensing applications.However,the large sensitive area is necessary to accommodate enough thermoelectric couples(TCs)for a high thermoelectric performance.This limits the potential in micro energy harvesting and ultrasensitive sensing applications.Here,we adopted an optimized MEMS-based process to fabricate the ultra-sensitive micro-thermoelectric device(μ-TED).With the help of MEMS-compatible electrochemical deposition,the small size(25μm),high aspect ratio(1:1.25),and alternating distributed P/N structures are achieved.As a result,theμ-TED realizes an ultra-high integration density of 19,900 thermoelectric couples per cm2.Moreover,it shows a great thermoelectric sensitivity of 212 mV/(K·cm2)and a competitive power factor of 0.51μW/(K2·cm2),which means theμ-TED is competent for miniaturized applications.Additionally,theμ-TED shows an ultra-low detection limit of 5 mm/s and a short response time of 100 ms,revealing great potential in fast detections of the ultra-low airflow.Furthermore,the ultra-sensitiveμ-TED is utilized as a flexible breath sensor,due to its compact size.The breath signal of different motion states is successfully detected.These results confirm that the ultra-sensitiveμ-TED holds outstanding potential for ultra-sensitive airflow sensing and energy harvesting devices.
文摘玄武岩纤维增强复合材料(basalt fiber-reinforced polymer,BFRP)具有优异的力学性能和可熔融再生特性,在汽车轻量化领域的应用前景广阔。针对某车型的铝制防撞装置,开展BFRP/铝混合防撞装置的多目标优化设计。首先,对BFRP层合板开展力学性能测试,并利用HyperMesh软件建立防撞装置有限元模型;其次,采用拉丁超立方抽样生成代理模型的训练样本,结合敏感度分析识别关键设计参数,并通过基于加权欧式距离的空间填充采样法来提升代理模型对响应指标的预测精度;最后,以防撞装置峰值载荷、总质量及横梁最大位移最小为优化目标,运用MOPSO(multi-objective particle swarm optimization,多目标粒子群优化)算法求解Pareto前沿,并基于熵权-TOPSIS(technique for order preference by similarity to an ideal solution,逼近理想解排序法)确定最优设计参数组合。结果显示:优化后防撞装置的峰值载荷降低了36.15%,总质量减小了12.23%,显著提升了耐撞性能并实现了轻量化目标。所提出的方法可为BFRP/铝混合防撞装置的轻量化设计提供一套系统性的解决方案。
基金supported by the National Natural Science Foundation of China(No.52177071).
文摘High proportion of renewable energies and the installation of power electronic devices(PEDs)pose tough challenges to the operation of power systems.In this paper,the remote coordination adjustment(RCA)of PEDs in stochastic scenarios is studied.The steady-state model for the AC/DC system with PEDs is first established,and the alternate iteration method based on linearization(AIML)is adopted,especially for efficient deterministic power flow calculation.Then,the RCA is proposed using a modular local sensitivity method combined with AIML,which can adjust the electrical variables by diverse PEDs with high efficiency.Additionally,the probabilistic power flow calculation using the quasi-Monte Carlo method with the adaptive sampling number(ASN-QMC)is introduced to keep the balance between the computational efficiency and accuracy,as well as demonstrating the positive impact of RCA by the PEDs in stochastic scenarios.The effectiveness of the proposed RCA is validated by a series of modified IEEE test systems.
基金Supported by the National Natural Science Foundation of China (Grant No. 50436020)
文摘An automatic cooling device has been developed by using a temperature-sensitive magnetic fluid as the coolant. A particle image velocimetry (PIV) system was used to measure the flow velocity of the fluid inside the loop. The efficiency of the device under varying conditions such as the heat load and the power of cooling were ex- perimentally investigated. The effect of cooperation between external magnetic field and thermal field on the performance of the device was studied. As expected, a continuous flow induced by the thermal and magnetic field was observed in the loop, where heat was transferred by the circulating magnetic fluid. The synergic effect between the magnetic field and the temperature gradient has impact on the performance of the device.
文摘通过超薄层插入与掺杂相结合的方式,分别以激光染料DCM(4-(Dicyanomethylene)-2-methyl-6-(4-dimet-hyl-aminostyryl)-4H-pyran)、铱配合物Ir(ppy)3(tris(2-phenylpyridine)iridium)和联苯乙烯衍生物BCzVB(1,4-bis[2-(3-N-ethylcarbazoryl)vinyl]benzene)为红色、绿色和蓝色发射体,制备了磷光敏化荧光白色有机电致发光器件(OLED).通过改变DCM超薄层在CBP:Ir(ppy)3掺杂层中的插入位置实现了白色发光,最高外量子效率为2.5%(电流效率为5.1 cd/A),最高亮度为12400 cd/m^(2),且其中一种器件在1 mA/cm^(2)的电流密度下,国际照明委员会(Commission Internationale de L'Eclairage,CIE)坐标达到了理想白光平衡点(0.33,0.33).白光的获得归因于Ir(ppy)3适合的掺杂比例和DCM适合的插入位置,较好地均衡了红、绿、蓝三基色发光比例.结果表明,通过磷光敏化荧光实现三线态激子将部分能量传递给单线态激子,可望实现高效率白色有机电致发光器件,从而降低能耗并为促进OLED的应用提供更多空间.
基金supported by the National Natural Science Foundation of China (NSFC) (60736005)Foundation for Innovative Research Groups of the NSFC (60721001)+2 种基金National High-Tech Research and Development Program of China (2007AA03Z424)Program for New Century Excellent Talents in University through(NCET-06-0812)Young Excellence Project of UESTC (060206)
文摘Efficient red organic light-emitting device consisted of a compound fluorescent-phosphor-sensitized emission layer was fabricated. A novel red fluorescent dye, 3-(dicyanomethylene)-5,5-dimethyl-1-(4-dimethylamino-styryl) cyclohexene (DCDDC), and a green phosphorescent dye, fac tris(2-phenylpyridine) iridium [Ir(ppy)3] were codoped into a host material 4,4'-N,N'-dicarbazolebiphe-nyl (CBP). By adjusting the component ratio of doping system, a series of devices with different concentration proportion of Ir(ppy)3:DCDDC were constructed. The results demonstrated that the device with 0.2 wt% DCDDC had a maximum power effi-ciency (ηp) of 2.12 lm/W at a current density of 0.1 mA/cm2, which was about 38% higher than that of conventional fluorescent device. When at a current density of 4 mA/cm2 (100 cd/m2) and 52 mA/cm2 (1000 cd/m2), the ηp percentage was about 160% and 143% higher than that of conventional device, respectively. A stable red light emission at a peak of 615 nm with Commissions Internationale de l'Eclairage coordinates near the region of (0.56, 0.42) in a wide bias range was also obtained. The improved performances were attributed to the efficient multiple-stage energy transfer from the host to the vip and the suppression of loss mechanism.
