A particular kind of triboelectrification occurs during the flow of liquids through tubes.Here,we used Faraday cups and Kelvin probes to investigate the charge of aqueous solutions and alcohols flowing through a polyt...A particular kind of triboelectrification occurs during the flow of liquids through tubes.Here,we used Faraday cups and Kelvin probes to investigate the charge of aqueous solutions and alcohols flowing through a polytetrafluorethylene tube.An excess of positive charges was observed in all liquids collected by the Faraday cup after the flow.While the tube displays a small potential during the flow,likely due to electrokinetic effects,a very high negative potential was observed after the completion of the flow.Aqueous solutions with varying pH showed significant differences in charge accumulation only at pH 2.93 and 4.99,while most of the charge accumulation can be suppressed using common surfactants.Alcohols displayed an inverse relationship between charge accumulation and carbon chain length,except for methanol.Thus,we used graphite-based nanocomposites as noncontact induction electrodes near the tube for flow sensing.A proof of concept was conducted using these induction electrodes to differentiate between water and ethanol flowing inside the tube,which was repeated thousands of times.Finally,the output voltage signal from the induction electrode was processed through an input signal filter and a microcontroller,where four lightemitting diodes(LEDs)were incorporated to indicate the flow and type of liquid.展开更多
We present a system-level model with an on-chip temperature compensation technique for a CMOS-MEMS monolithic calorimetric flow sensing SoC.The model encompasses mechanical,thermal,and electrical domains to facilitate...We present a system-level model with an on-chip temperature compensation technique for a CMOS-MEMS monolithic calorimetric flow sensing SoC.The model encompasses mechanical,thermal,and electrical domains to facilitate the co-design of a MEMS sensor and CMOS interface circuits on the EDA platform.The compensation strategy is implemented on-chip with a variable temperature difference heating circuit.Results show that the linear programming for the low-temperature drift in the SoC output is characterized by a compensation resistor Rc with a resistance value of 748.21Ωand a temperature coefficient of resistance of 3.037×10−3℃^(−1) at 25℃.Experimental validation demonstrates that within an ambient temperature range of 0–50℃ and a flow range of 0-10 m/s,the temperature drift of the sensor is reduced to±1.6%,as compared to±8.9%observed in a counterpart with the constant temperature difference circuit.Therefore,this on-chip temperature-compensated CMOS-MEMS flow sensing SoC is promising for low-cost sensing applications such as respiratory monitoring and smart energy-efficient buildings.展开更多
Single-walled carbon nanotubes(SWCNTs)present excellent electronic and mechanical properties desired in wearable and flexible devices.The preparation of SWCNT films is the first step for fabricating various devices.Th...Single-walled carbon nanotubes(SWCNTs)present excellent electronic and mechanical properties desired in wearable and flexible devices.The preparation of SWCNT films is the first step for fabricating various devices.This work developed a scalable and feasible method to assemble SWCNT thin films on water surfaces based on Marangoni flow induced by surface tension gradient.The films possess a large area of 40 cm×30 cm(extensible),a tunable thickness of 15∼150 nm,a high transparency of up to 96%,and a decent conductivity.They are ready to be directly transferred to various substrates,including flexible ones.Flexible strain sensors were fabricated with the films on flexible substrates.These sensors worked with high sensitivity and repeatability.By realizing multi-functional human motion sensing,including responding to voices,monitoring artery pulses,and detecting knuckle and muscle actions,the assembled SWCNT films demonstrated the potential for application in smart devices.展开更多
基金supported by the Brazilian agencies MCTIC/CNPq(465452/2014-0),FAPESP(2014/50906-9),and CAPES-Finance Code 001 through INCT/INOMAT(National Institute for Complex Functional Materials)and MCT/Finep/CT-Infra 02/2010.Yan Araujo Santos da Campo acknowledges CAPES(88887.674802/2022-00)for receiving a master’s degree fellowship.Authors have used large language models(ChatGTP)to improve readability and language.
文摘A particular kind of triboelectrification occurs during the flow of liquids through tubes.Here,we used Faraday cups and Kelvin probes to investigate the charge of aqueous solutions and alcohols flowing through a polytetrafluorethylene tube.An excess of positive charges was observed in all liquids collected by the Faraday cup after the flow.While the tube displays a small potential during the flow,likely due to electrokinetic effects,a very high negative potential was observed after the completion of the flow.Aqueous solutions with varying pH showed significant differences in charge accumulation only at pH 2.93 and 4.99,while most of the charge accumulation can be suppressed using common surfactants.Alcohols displayed an inverse relationship between charge accumulation and carbon chain length,except for methanol.Thus,we used graphite-based nanocomposites as noncontact induction electrodes near the tube for flow sensing.A proof of concept was conducted using these induction electrodes to differentiate between water and ethanol flowing inside the tube,which was repeated thousands of times.Finally,the output voltage signal from the induction electrode was processed through an input signal filter and a microcontroller,where four lightemitting diodes(LEDs)were incorporated to indicate the flow and type of liquid.
基金supported by the National Natural Science Foundation of China(62474115,52105582)Natural Science Foundation of Guangdong Province(2024A1515030026,2022A1515010894)+1 种基金Fundamental Research Foundation of Shenzhen(JCYJ20210324095210030,JCYJ20220818095810023,ZDSYS20220527171402005)the State Key Laboratory of Radio Frequency Heterogeneous Integration(Independent Scientific Research Program No.2024013)for Linze Hong,Ke Xiao,Xiangyu Song,and Wei Xu.
文摘We present a system-level model with an on-chip temperature compensation technique for a CMOS-MEMS monolithic calorimetric flow sensing SoC.The model encompasses mechanical,thermal,and electrical domains to facilitate the co-design of a MEMS sensor and CMOS interface circuits on the EDA platform.The compensation strategy is implemented on-chip with a variable temperature difference heating circuit.Results show that the linear programming for the low-temperature drift in the SoC output is characterized by a compensation resistor Rc with a resistance value of 748.21Ωand a temperature coefficient of resistance of 3.037×10−3℃^(−1) at 25℃.Experimental validation demonstrates that within an ambient temperature range of 0–50℃ and a flow range of 0-10 m/s,the temperature drift of the sensor is reduced to±1.6%,as compared to±8.9%observed in a counterpart with the constant temperature difference circuit.Therefore,this on-chip temperature-compensated CMOS-MEMS flow sensing SoC is promising for low-cost sensing applications such as respiratory monitoring and smart energy-efficient buildings.
基金supported by National Natural Science Foundation of China(22120102004,21631002)Ministry of Science and Technology of China(2016YFA0201904)+3 种基金Shenzhen KQTD Project(KQTD20180411143400981)Beijing National Laboratory for Molecular Sciences(BNLMS-CXTD-202001)JSPS KAKENHI(JP20H00220)and by JST,CREST(JPMJCR20B5),Japan,。
文摘Single-walled carbon nanotubes(SWCNTs)present excellent electronic and mechanical properties desired in wearable and flexible devices.The preparation of SWCNT films is the first step for fabricating various devices.This work developed a scalable and feasible method to assemble SWCNT thin films on water surfaces based on Marangoni flow induced by surface tension gradient.The films possess a large area of 40 cm×30 cm(extensible),a tunable thickness of 15∼150 nm,a high transparency of up to 96%,and a decent conductivity.They are ready to be directly transferred to various substrates,including flexible ones.Flexible strain sensors were fabricated with the films on flexible substrates.These sensors worked with high sensitivity and repeatability.By realizing multi-functional human motion sensing,including responding to voices,monitoring artery pulses,and detecting knuckle and muscle actions,the assembled SWCNT films demonstrated the potential for application in smart devices.
