Heating,ventilation,and air conditioning(HVAC)systems account for one-third of the total energy consumption in office buildings.The use of airflow measurements to control the operation of HVAC systems can reduce energ...Heating,ventilation,and air conditioning(HVAC)systems account for one-third of the total energy consumption in office buildings.The use of airflow measurements to control the operation of HVAC systems can reduce energy consumption;thus,a sensor capable of monitoring airflow in a duct system is critical.Triboelectric nanogenerators(TENGs)can be utilized as self-powered sensors in airflow-driven TENGs(ATENGs)as self-powered sensors.By employing ferroelectric materials and surface modifications,the surface charges of TENGs can be increased.In this study,fibrous-mat TENGs were prepared using ferroelectric materials consisting of poly(vinylidene fluoride-co-trifluoroethylene)(PVDF-TrFE)and polyamide 11(nylon-11).And these materials were subsequently investigated.Poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate)was added to PVDF-TrFE to enhance the ferroelectric crystalline phase.X-ray diffraction analysis revealed that this incorporation affects theβphase.In addition,the surface of nylon-11 was modified using the electrospray technique for post-treatment,thereby improving the interfacial adhesion between the fibers.These materials were then utilized in fibrous-mat ATENGs(FM-ATENGs)to demonstrate their practical application.The FM-ATENGs can be effectively used in an Arduino airflowcheck sensor,showcasing their potential for application in HVAC systems,to enhance airflow control and energy efficiency.展开更多
Crickets, similar to some other insects, have highly sensitive filiform hairs on their cerci that can detect miniscule changes in airflow. This study imitates the perception mechanism of these filiform sensory hairs o...Crickets, similar to some other insects, have highly sensitive filiform hairs on their cerci that can detect miniscule changes in airflow. This study imitates the perception mechanism of these filiform sensory hairs of crickets by designing and fabricating a Multi-electrode Metal Core Piezoelectric Fiber （MMPF）-based airflow sensor. Four longitudinal conductive sheets were coated symmetrically on their surfaces with Metal-core Piezoceramic Fibers （MPF）. The four fan-shaped piezoelectric ceramics with surface electrode covers were polarized. After successful polarization, the cantilevered MMPF could be used as an airflow sensor. The four electrodes on the surface were symmetrically divided into two groups. Therefore, two signals can be produced by a single fiber sensor. The theoretical model of an MMPF airflow sensor has been established. The model indicates that the ratio of the two signals is equivalent to the tangent of the airflow angle. Furthermore, the sum of the squares of the two signals is not dependent on the angle, but reflects the velocity of the airflow. Therefore, a single MMPF can be used to measure both the direction and amplitude for a given airflow. The theoretical model has been confirmed via experimental measurements.展开更多
This paper presents a novel flexible airflow sensor based on four curved microcantilevers arranged in a cross-form configuration.A self-bending method based on MEMS technology has been used to fabricate the curved mic...This paper presents a novel flexible airflow sensor based on four curved microcantilevers arranged in a cross-form configuration.A self-bending method based on MEMS technology has been used to fabricate the curved microcantilevers structure,and this method can transfer a 2D plane structure into a 3D structure with good consistency in the morphology.The curved microcantilever consists of a polyimide(PI)top layer,silicon(Si)bottom layer,and platinum(Pt)piezoresistor at the root of the cantilever.The difference in the in-plane residual stress between the PI and Si layers bent the microcantilever upward.The curved-up microcantilever transfers the fluidic momentum that acts on it to drag force,which deflects the curved-up microcantilever and changes the resistance of the piezoresistor.To realize temperature compensation and decrease the noise,a reference resistor and an ambient temperature detector were integrated for the Wheatstone half-bridge measurement and temperature monitoring,respectively.The cross-form configuration of the curved-up cantilevers has high sensitivity advantages and possesses direction-sensing ability.Experimental results show that the sensitivity of the sensors increased as a function of the airflow velocity,and the sensors exhibited a maximum resolution of 4 mm⋅s^(−1) and a maximum sensitivity of 60.35 mV⋅(ms^(−1))^(−1) when the airflow velocity was larger than 38.5 m⋅s^(−1).展开更多
An integrated sensor system is implemented using inter-integrated circuit mode (I2C) software, utilizing the PIC182585 MPLAB embedded control system utilizing hardware. The hardware implementation features high level ...An integrated sensor system is implemented using inter-integrated circuit mode (I2C) software, utilizing the PIC182585 MPLAB embedded control system utilizing hardware. The hardware implementation features high level of integration, reliability, high precision, and high speed communications. The system was demonstrated by temperature and CO2 sensors. An extension for Zigbee system is proposed to enhance the security of the integrated system. A bi-directional air/liquid flow sensor is also added to detect the flow magnitude and direction that can be applied to heating, ventilating, and air-conditioning (HVAC), local and national security within subway systems, and medical equipment. The hardware design of the flow sensor included one heating element and two sensing elements to detect the bi-directional flow. Platinum sensors were found to be of high sensitivity and linear characteristics within 0℃ to 100℃ range, and their high temperature coefficient (0.00385 Ω/Ω/℃). Polyimide thin film heater was used as the heating element due to its high throughput and good thermal efficiency. Two bridge circuits were also designed to sense the temperature distribution in the vicinity of the sensing elements. Three high precision instrumentation low power amplifiers with offset voltage ~2.5 μV (50 μV max) were used for the overall design. The system security is also enhanced with the detection of poison gas using Carbon Nanotube devices (CNT). An antenna system was designed, and a frequency shift was detected to designate the type of poison gas used for a general threat.展开更多
模仿昆虫感觉毛的结构,设计制备了表面对称电极含金属芯PVDF气流传感器SMPF(Symmetric Metal core PVDF Fiber)。利用自制的拉制纤维设备,制备了SMPF胚体。在表面涂镀对称电极后,经过高温极化、电极封装等工艺后,成功制备了SMPF气流传...模仿昆虫感觉毛的结构,设计制备了表面对称电极含金属芯PVDF气流传感器SMPF(Symmetric Metal core PVDF Fiber)。利用自制的拉制纤维设备,制备了SMPF胚体。在表面涂镀对称电极后,经过高温极化、电极封装等工艺后,成功制备了SMPF气流传感器。基于第1类压电方程和流体力学理论,建立了悬臂梁结构的SMPF气流传感模型,分析了传感器输出信号与纤维长度、气流速度以及气流作用方向之间的关系。将悬臂梁结构的SMPF安置在气流流场中,进行冲击气流测试实验。实验结果表明,SMPF气流传感器的输出信号与纤维长度成非线性关系,与气流速度成平方关系,与气流作用方向成"8"字形关系。实验结果验证了理论模型,表明SMPF传感器能够感知气流的速度和作用方向,具有较广泛的工程应用前景。展开更多
基金supported by the Korea Institute of Energy Technology Evaluation and Planning(KETEP)grant funded by the Korean government(MOTIE)(grant number:20202020800030).
文摘Heating,ventilation,and air conditioning(HVAC)systems account for one-third of the total energy consumption in office buildings.The use of airflow measurements to control the operation of HVAC systems can reduce energy consumption;thus,a sensor capable of monitoring airflow in a duct system is critical.Triboelectric nanogenerators(TENGs)can be utilized as self-powered sensors in airflow-driven TENGs(ATENGs)as self-powered sensors.By employing ferroelectric materials and surface modifications,the surface charges of TENGs can be increased.In this study,fibrous-mat TENGs were prepared using ferroelectric materials consisting of poly(vinylidene fluoride-co-trifluoroethylene)(PVDF-TrFE)and polyamide 11(nylon-11).And these materials were subsequently investigated.Poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate)was added to PVDF-TrFE to enhance the ferroelectric crystalline phase.X-ray diffraction analysis revealed that this incorporation affects theβphase.In addition,the surface of nylon-11 was modified using the electrospray technique for post-treatment,thereby improving the interfacial adhesion between the fibers.These materials were then utilized in fibrous-mat ATENGs(FM-ATENGs)to demonstrate their practical application.The FM-ATENGs can be effectively used in an Arduino airflowcheck sensor,showcasing their potential for application in HVAC systems,to enhance airflow control and energy efficiency.
基金This research was supported by the Nationa Natural Science Foundation of China （Grant No 51275447）.
文摘Crickets, similar to some other insects, have highly sensitive filiform hairs on their cerci that can detect miniscule changes in airflow. This study imitates the perception mechanism of these filiform sensory hairs of crickets by designing and fabricating a Multi-electrode Metal Core Piezoelectric Fiber （MMPF）-based airflow sensor. Four longitudinal conductive sheets were coated symmetrically on their surfaces with Metal-core Piezoceramic Fibers （MPF）. The four fan-shaped piezoelectric ceramics with surface electrode covers were polarized. After successful polarization, the cantilevered MMPF could be used as an airflow sensor. The four electrodes on the surface were symmetrically divided into two groups. Therefore, two signals can be produced by a single fiber sensor. The theoretical model of an MMPF airflow sensor has been established. The model indicates that the ratio of the two signals is equivalent to the tangent of the airflow angle. Furthermore, the sum of the squares of the two signals is not dependent on the angle, but reflects the velocity of the airflow. Therefore, a single MMPF can be used to measure both the direction and amplitude for a given airflow. The theoretical model has been confirmed via experimental measurements.
基金supported financially by the National Natural Science Foundation of China under contract No.51975030 and No.52022008.
文摘This paper presents a novel flexible airflow sensor based on four curved microcantilevers arranged in a cross-form configuration.A self-bending method based on MEMS technology has been used to fabricate the curved microcantilevers structure,and this method can transfer a 2D plane structure into a 3D structure with good consistency in the morphology.The curved microcantilever consists of a polyimide(PI)top layer,silicon(Si)bottom layer,and platinum(Pt)piezoresistor at the root of the cantilever.The difference in the in-plane residual stress between the PI and Si layers bent the microcantilever upward.The curved-up microcantilever transfers the fluidic momentum that acts on it to drag force,which deflects the curved-up microcantilever and changes the resistance of the piezoresistor.To realize temperature compensation and decrease the noise,a reference resistor and an ambient temperature detector were integrated for the Wheatstone half-bridge measurement and temperature monitoring,respectively.The cross-form configuration of the curved-up cantilevers has high sensitivity advantages and possesses direction-sensing ability.Experimental results show that the sensitivity of the sensors increased as a function of the airflow velocity,and the sensors exhibited a maximum resolution of 4 mm⋅s^(−1) and a maximum sensitivity of 60.35 mV⋅(ms^(−1))^(−1) when the airflow velocity was larger than 38.5 m⋅s^(−1).
文摘An integrated sensor system is implemented using inter-integrated circuit mode (I2C) software, utilizing the PIC182585 MPLAB embedded control system utilizing hardware. The hardware implementation features high level of integration, reliability, high precision, and high speed communications. The system was demonstrated by temperature and CO2 sensors. An extension for Zigbee system is proposed to enhance the security of the integrated system. A bi-directional air/liquid flow sensor is also added to detect the flow magnitude and direction that can be applied to heating, ventilating, and air-conditioning (HVAC), local and national security within subway systems, and medical equipment. The hardware design of the flow sensor included one heating element and two sensing elements to detect the bi-directional flow. Platinum sensors were found to be of high sensitivity and linear characteristics within 0℃ to 100℃ range, and their high temperature coefficient (0.00385 Ω/Ω/℃). Polyimide thin film heater was used as the heating element due to its high throughput and good thermal efficiency. Two bridge circuits were also designed to sense the temperature distribution in the vicinity of the sensing elements. Three high precision instrumentation low power amplifiers with offset voltage ~2.5 μV (50 μV max) were used for the overall design. The system security is also enhanced with the detection of poison gas using Carbon Nanotube devices (CNT). An antenna system was designed, and a frequency shift was detected to designate the type of poison gas used for a general threat.
文摘模仿昆虫感觉毛的结构,设计制备了表面对称电极含金属芯PVDF气流传感器SMPF(Symmetric Metal core PVDF Fiber)。利用自制的拉制纤维设备,制备了SMPF胚体。在表面涂镀对称电极后,经过高温极化、电极封装等工艺后,成功制备了SMPF气流传感器。基于第1类压电方程和流体力学理论,建立了悬臂梁结构的SMPF气流传感模型,分析了传感器输出信号与纤维长度、气流速度以及气流作用方向之间的关系。将悬臂梁结构的SMPF安置在气流流场中,进行冲击气流测试实验。实验结果表明,SMPF气流传感器的输出信号与纤维长度成非线性关系,与气流速度成平方关系,与气流作用方向成"8"字形关系。实验结果验证了理论模型,表明SMPF传感器能够感知气流的速度和作用方向,具有较广泛的工程应用前景。
