The research on flexible pressure sensors has drawn widespread attention in recent years,especially in the fields of health care and intelligent robots.In practical applications,the sensitivity of sensors directly aff...The research on flexible pressure sensors has drawn widespread attention in recent years,especially in the fields of health care and intelligent robots.In practical applications,the sensitivity of sensors directly affects the precision and integrity of weak pressure signals.Here,a pressure sensor with high sensitivity and a wide measurement range composed of porous fiber paper and 3D patterned electrodes is proposed.Multi-walled carbon nanotubes with excellent conductivity were evenly sprayed on the fiber paper to form the natural spatial conducting networks,while the copper-deposited polydimethylsiloxane films with micropyramids array were used as electrodes and flexible substrates.Increased conducting paths between electrodes and fibers can be obtained when high-density micro-pyramids fall into the porous structures of the fiber paper under external pressure,thereby promoting the pressure sensor to show an ultra-high sensitivity of 17.65 kPa^(-1)in the pressure range of 0–2 kPa,16 times that of the device without patterned electrodes.Besides,the sensor retains a high sensitivity of 2.06 kPa^(-1)in an ultra-wide measurement range of 150 kPa.Moreover,the sensor can detect various physiological signals,including pulse and voice,while attached to the human skin.This work provides a novel strategy to significantly improve the sensitivity and measurement range of flexible pressure sensors,as well as demonstrates attractive applications in physiological signal monitoring.展开更多
The thermal-electrical characteristic of a GaN light-emitting diode （LED） with the hybrid transparent conductive layers （TCLs） of graphene （Gr） and NiOx is investigated by a finite element method. It is indicate...The thermal-electrical characteristic of a GaN light-emitting diode （LED） with the hybrid transparent conductive layers （TCLs） of graphene （Gr） and NiOx is investigated by a finite element method. It is indicated that the LED with the compound TCL of 3-layer Gr and 1 nm NiOx has the best thermal-electrical performance from the view point of the maximum temperature and the current density deviation of multiple quantum wells, and the maximum temperature occurs near the n-electrode rather than p-electrode. Furthermore, to depress the current crowding on the LED, the electrode pattern parameters including p- and n-electrode length, p-electrode buried depth and the distance of n-electrode to active area are optimized. It is found that either increasing p- or n-electrode length and buried depth or decreasing the distance of n-electrode from the active area will decrease the temperature of the LED, while the increase of the n-electrode length has more prominent effect. Typically, when the n-electrode length increases to 0.8 times of the chip size, the temperature of the GaN LED with the inm NiOx/3-1ayer-Gr hybrid TCLs could drop about 7K and the current density uniformity could increase by 23.8%, compared to 0.4 times of the chip size. This new finding will be beneficial for improvement of the thermal- electrical performance of LEDs with various conductive TCLs such as NiOx/Gr or ITO/Gr as current spreading layers.展开更多
Zn anode-based electrochromic devices(ZECDs)stand out as a highly promising technology in the upcoming era of multifunctional electronic devices,offering a blend of electrochromic capabilities and energy storage funct...Zn anode-based electrochromic devices(ZECDs)stand out as a highly promising technology in the upcoming era of multifunctional electronic devices,offering a blend of electrochromic capabilities and energy storage functions within a single transparent platform.However,significant challenges persist in achieving efficient patterning,ensuring long-term stability,and fast color-switching kinetics for these devices.In this study,heterogeneous tungsten oxide nanowires(W_(17)O_(47)/Na_(0.1)WO_(3),WNOs)are formulated into inkjet printing ink to assemble patternable ZECDs.The heterogeneous electrode structure of WNO enables a highly capacitive-controlled mechanism that promotes fast electrochromic/electrochemical behavior.Notably,by utilizing a three-dimensional MXene mesh modified substrate,the inkjet-printed ZECDs exhibit a wide optical modulation range of 69.13%,rapid color-changing kinetics(t_(c)=4.1 s,t_(b)=5.4 s),and highly reversible capacities of 70 mAh cm^(-2)over 1000 cycles.This scalable strategy develops the patterned electrodes with a wide optical modulation range and substantial energy storage properties,offering promising prospects for their application in next-generation smart electronics.展开更多
Air-coupled ultrasonic transducers(ACUTs)have been applied in industrial non-destructive testing,structural health monitoring,and medical ultrasound.However,conventional passive focusing methods often result in undesi...Air-coupled ultrasonic transducers(ACUTs)have been applied in industrial non-destructive testing,structural health monitoring,and medical ultrasound.However,conventional passive focusing methods often result in undesired effects on sensitivity due to variations in acoustic impedance matching conditions,which are critical in ACUT design,where sensitivity is the top priority.Accordingly,a novel active focusing method for ACUTs is proposed in this study.The key idea is to create multiple concentric ring electrode patterns on a bulk planar piezoelectric plate so that a quarter-wavelength acoustic impedance matching layer of uniform thickness can be attached onto the plate.The initial structural parameters of the electrode patterns are determined based on the design methodology of a Fresnel zone plate(FZP).Those parameters are optimized through finite element simulation,with the transducer’s sensitivity as the objective function,while ensuring only slight variations to the focal length and lateral resolution.Single-sided multiple concentric ring electrode patterns are then fabricated on 1-3 piezoelectric fiber/epoxy resin composite plate by screen printing and combined with a high-performance acoustic impedance matching layer made from epoxy resin composite filled with hollow glass microspheres.The planar active focusing ACUT is developed,while two types of conventional passive focusing ACUTs using FZP and concave lens are fabricated with the same piezoelectric and acoustic matching materials.Comparative experimental testing is carried out.The developed planar active-focusing ACUT achieves significant sensitivity improvements of 7.1 and 17.4dB,respectively,while maintaining comparable radial and axial full-width at half maximum.The results of this study offer a novel approach for the design of high-performance ACUTs.展开更多
Flexible wearable sensors are crucial for health monitoring and motion detection,but they are often hindered by inadequate breathability and comfort.Here,we present a breathable pressure sensor that combines MXene nan...Flexible wearable sensors are crucial for health monitoring and motion detection,but they are often hindered by inadequate breathability and comfort.Here,we present a breathable pressure sensor that combines MXene nanosheets with a porous polyester textile,achieving high sensitivity(652.1 kPa^(-1)),a broad detection range(0-60 kPa),and a fast response/recovery time(36 ms/20 ms).The serpentine electrode pattern enhances tensile strength and sensitivity,while electrospun TPU nanofiber membranes improve breathability and signal recovery.A 4×4 electrode array allows for precise pulse localization,while machine learning algorithms enable real-time blood pressure prediction.This innovative design demonstrates significant potential for wearable health monitoring and cardiovascular diagnostics.展开更多
基金supported by the National Key R&D Program of China(Grant Nos.2019YFE0120300,2019YFF0301802)National Natural Science Foundation of China(Grant Nos.52175554,62101513,51975542)+3 种基金Natural Science Foundation of Shanxi Province(Grant No.201801D121152)Shanxi“1331 Project”Key Subject Construction(Grant No.1331KSC)National Defense Fundamental Research ProjectResearch Project Supported by Shan Xi Scholarship Council of China(Grant No.2020-109)。
文摘The research on flexible pressure sensors has drawn widespread attention in recent years,especially in the fields of health care and intelligent robots.In practical applications,the sensitivity of sensors directly affects the precision and integrity of weak pressure signals.Here,a pressure sensor with high sensitivity and a wide measurement range composed of porous fiber paper and 3D patterned electrodes is proposed.Multi-walled carbon nanotubes with excellent conductivity were evenly sprayed on the fiber paper to form the natural spatial conducting networks,while the copper-deposited polydimethylsiloxane films with micropyramids array were used as electrodes and flexible substrates.Increased conducting paths between electrodes and fibers can be obtained when high-density micro-pyramids fall into the porous structures of the fiber paper under external pressure,thereby promoting the pressure sensor to show an ultra-high sensitivity of 17.65 kPa^(-1)in the pressure range of 0–2 kPa,16 times that of the device without patterned electrodes.Besides,the sensor retains a high sensitivity of 2.06 kPa^(-1)in an ultra-wide measurement range of 150 kPa.Moreover,the sensor can detect various physiological signals,including pulse and voice,while attached to the human skin.This work provides a novel strategy to significantly improve the sensitivity and measurement range of flexible pressure sensors,as well as demonstrates attractive applications in physiological signal monitoring.
基金Supported by the Foundation of the State Key Laboratory of Mechanical Transmission of Chongqing University under Grant Nos SKLMT-KFKT-201419 and SKLM-ZZKT-2015Z16the National High-Technology Research and Development Program of China under Grant No 2015AA034801+4 种基金the National Natural Science Foundation of China under Grant Nos 11374359,11304405,11544010 and 11547305the Chongqing Education Commission Scientific Project under Grant No KJ132209the Natural Science Foundation of Chongqing under Grant Nos cstc2013jcyjA50031,cstc2015jcyjA50035 and cstc2015jcyjA1660the Fundamental Research Funds for the Central Universities under Grant Nos CDJZR14135502,CDJZR14300050,106112016CDJZR288805 and 106112015CDJXY300002the Sharing Fund of Large-scale Equipment of Chongqing University under Grant Nos 201512150017,201512150029 and 201512150030
文摘The thermal-electrical characteristic of a GaN light-emitting diode （LED） with the hybrid transparent conductive layers （TCLs） of graphene （Gr） and NiOx is investigated by a finite element method. It is indicated that the LED with the compound TCL of 3-layer Gr and 1 nm NiOx has the best thermal-electrical performance from the view point of the maximum temperature and the current density deviation of multiple quantum wells, and the maximum temperature occurs near the n-electrode rather than p-electrode. Furthermore, to depress the current crowding on the LED, the electrode pattern parameters including p- and n-electrode length, p-electrode buried depth and the distance of n-electrode to active area are optimized. It is found that either increasing p- or n-electrode length and buried depth or decreasing the distance of n-electrode from the active area will decrease the temperature of the LED, while the increase of the n-electrode length has more prominent effect. Typically, when the n-electrode length increases to 0.8 times of the chip size, the temperature of the GaN LED with the inm NiOx/3-1ayer-Gr hybrid TCLs could drop about 7K and the current density uniformity could increase by 23.8%, compared to 0.4 times of the chip size. This new finding will be beneficial for improvement of the thermal- electrical performance of LEDs with various conductive TCLs such as NiOx/Gr or ITO/Gr as current spreading layers.
基金funding from the Natural Science Foundation of Jiangsu Province(BK20210480)the grant from National Innovation Center of Advanced Dyeing&Finishing Technology(2022GCJJ08).
文摘Zn anode-based electrochromic devices(ZECDs)stand out as a highly promising technology in the upcoming era of multifunctional electronic devices,offering a blend of electrochromic capabilities and energy storage functions within a single transparent platform.However,significant challenges persist in achieving efficient patterning,ensuring long-term stability,and fast color-switching kinetics for these devices.In this study,heterogeneous tungsten oxide nanowires(W_(17)O_(47)/Na_(0.1)WO_(3),WNOs)are formulated into inkjet printing ink to assemble patternable ZECDs.The heterogeneous electrode structure of WNO enables a highly capacitive-controlled mechanism that promotes fast electrochromic/electrochemical behavior.Notably,by utilizing a three-dimensional MXene mesh modified substrate,the inkjet-printed ZECDs exhibit a wide optical modulation range of 69.13%,rapid color-changing kinetics(t_(c)=4.1 s,t_(b)=5.4 s),and highly reversible capacities of 70 mAh cm^(-2)over 1000 cycles.This scalable strategy develops the patterned electrodes with a wide optical modulation range and substantial energy storage properties,offering promising prospects for their application in next-generation smart electronics.
基金supported by the National Natural Science Foundation of China(Grant No.52205564)the Foundation of Natural Science Foundation of Hubei Province,China(Grant No.2022CFB898).
文摘Air-coupled ultrasonic transducers(ACUTs)have been applied in industrial non-destructive testing,structural health monitoring,and medical ultrasound.However,conventional passive focusing methods often result in undesired effects on sensitivity due to variations in acoustic impedance matching conditions,which are critical in ACUT design,where sensitivity is the top priority.Accordingly,a novel active focusing method for ACUTs is proposed in this study.The key idea is to create multiple concentric ring electrode patterns on a bulk planar piezoelectric plate so that a quarter-wavelength acoustic impedance matching layer of uniform thickness can be attached onto the plate.The initial structural parameters of the electrode patterns are determined based on the design methodology of a Fresnel zone plate(FZP).Those parameters are optimized through finite element simulation,with the transducer’s sensitivity as the objective function,while ensuring only slight variations to the focal length and lateral resolution.Single-sided multiple concentric ring electrode patterns are then fabricated on 1-3 piezoelectric fiber/epoxy resin composite plate by screen printing and combined with a high-performance acoustic impedance matching layer made from epoxy resin composite filled with hollow glass microspheres.The planar active focusing ACUT is developed,while two types of conventional passive focusing ACUTs using FZP and concave lens are fabricated with the same piezoelectric and acoustic matching materials.Comparative experimental testing is carried out.The developed planar active-focusing ACUT achieves significant sensitivity improvements of 7.1 and 17.4dB,respectively,while maintaining comparable radial and axial full-width at half maximum.The results of this study offer a novel approach for the design of high-performance ACUTs.
基金supported by the Natural Science Foundation of Shandong Province(No.ZR2022QF120)Qingdao Postdoctoral Fund(No.QDBSH20230101005).
文摘Flexible wearable sensors are crucial for health monitoring and motion detection,but they are often hindered by inadequate breathability and comfort.Here,we present a breathable pressure sensor that combines MXene nanosheets with a porous polyester textile,achieving high sensitivity(652.1 kPa^(-1)),a broad detection range(0-60 kPa),and a fast response/recovery time(36 ms/20 ms).The serpentine electrode pattern enhances tensile strength and sensitivity,while electrospun TPU nanofiber membranes improve breathability and signal recovery.A 4×4 electrode array allows for precise pulse localization,while machine learning algorithms enable real-time blood pressure prediction.This innovative design demonstrates significant potential for wearable health monitoring and cardiovascular diagnostics.
