Perovskite-based photovoltaic materials have been attracting attention for their strikingly improved performance at converting sunlight into electricity.The beneficial and unique optoelectronic characteristics of pero...Perovskite-based photovoltaic materials have been attracting attention for their strikingly improved performance at converting sunlight into electricity.The beneficial and unique optoelectronic characteristics of perovskite structures enable researchers to achieve an incredibly remarkable power conversion efficiency.Flexible hybrid perovskite photovoltaics promise emerging applications in a myriad of optoelectronic and wearable/portable device applications owing to their inherent intriguing physicochemical and photophysical properties which enabled researchers to take forward advanced research in this growing field.Flexible perovskite photovoltaics have attracted significant attention owing to their fascinating material properties with combined merits of high efficiency,light-weight,flexibility,semitransparency,compatibility towards roll-to-roll printing,and large-area mass-scale production.Flexible perovskite-based solar cells comprise of 4 key components that include a flexible substrate,semi-transparent bottom contact electrode,perovskite(light absorber layer)and charge transport(electron/hole)layers and top(usually metal)electrode.Among these components,interfacial layers and contact electrodes play a pivotal role in influencing the overall photovoltaic performance.In this comprehensive review article,we focus on the current developments and latest progress achieved in perovskite photovoltaics concerning the charge selective transport layers/electrodes toward the fabrication of highly stable,efficient flexible devices.As a concluding remark,we briefly summarize the highlights of the review article and make recommendations for future outlook and investigation with perspectives on the perovskite-based optoelectronic functional devices that can be potentially utilized in smart wearable and portable devices.展开更多
The relative motion of the electrodes is a typical feature of sliding electrical contact systems.The system fault caused by the arc is the key problem that restricts the service life of the sliding electrical contact ...The relative motion of the electrodes is a typical feature of sliding electrical contact systems.The system fault caused by the arc is the key problem that restricts the service life of the sliding electrical contact system.In this paper,an arcing experimental platform that can accurately control the relative speed and distance of electrodes is built,and the influence of different electrode speeds and electrode distances on arc motion characteristics is explored.It is found that there are three different modes of arc root motion:single arc root motion mode,single and double arc roots alternating motion mode,and multiple arc roots motion mode.The physical process and influence mechanism of different arc root motion modes are further studied,and the corresponding relationship between arc root motion modes and electrode speed is revealed.In addition,to further explore the distribution characteristics of arc temperature and its influencing factors,an arc magnetohydrodynamic model under the relative motion of electrodes is established,and the variation law of arc temperature under the effect of different electrode speeds and electrode distances is summarized.Finally,the influence mechanism of electrode speed and electrode distance on arc temperature,arc root distance,and arc root speed is clarified.The research results enrich the research system of arc dynamic characteristics in the field of sliding electrical contact,and provide theoretical support for restraining arc erosion and improving the service life of the sliding electrical contact system.展开更多
Metal–semiconductor contacts are crucial components in semiconductor devices.Ultrathin two-dimensional transition-metal dichalcogenide semiconductors can sustain transistor scaling for next-generation integrated circ...Metal–semiconductor contacts are crucial components in semiconductor devices.Ultrathin two-dimensional transition-metal dichalcogenide semiconductors can sustain transistor scaling for next-generation integrated circuits.However,their performance is often degraded by conventional metal deposition,which results in a high barrier due to chemical disorder and Fermi-level pinning(FLP).Although,transferring electrodes can address these issues,they are limited in achieving universal transfer of full-class metals due to strong adhesion between pre-deposited metals and substrates.Here,we propose a nanobelt-assisted transfer strategy that can avoid the adhesion limitation and enables the universal transfer of over 20 different types of electrodes.Our contacts obey the Schottky–Mott rule and exhibit a FLP of S=0.99.Both the electron and hole contacts show record-low Schottky barriers of 4.2 and 11.2 meV,respectively.As a demonstration,we construct a doping-free WSe_(2) inverter with these high-performance contacts,which exhibits a static power consumption of only 58 pW.This strategy provides a universal method of electrode preparation for building high-performance post-Moore electronic devices.展开更多
The utilization of solid-state electrolytes(SSEs)presents a promising solution to the issues of safety concern and shuttle effect in Li–S batteries,which has garnered significant interest recently.However,the high in...The utilization of solid-state electrolytes(SSEs)presents a promising solution to the issues of safety concern and shuttle effect in Li–S batteries,which has garnered significant interest recently.However,the high interfacial impedances existing between the SSEs and the electrodes(both lithium anodes and sulfur cathodes)hinder the charge transfer and intensify the uneven deposition of lithium,which ultimately result in insufficient capacity utilization and poor cycling stability.Hence,the reduction of interfacial resistance between SSEs and electrodes is of paramount importance in the pursuit of efficacious solid-state batteries.In this review,we focus on the experimental strategies employed to enhance the interfacial contact between SSEs and electrodes,and summarize recent progresses of their applications in solidstate Li–S batteries.Moreover,the challenges and perspectives of rational interfacial design in practical solid-state Li–S batteries are outlined as well.We expect that this review will provide new insights into the further technique development and practical applications of solid-state lithium batteries.展开更多
Al electrodes are well known as ohmic contact electrodes for the PTC component , the influence of their thickness on final component properties was investigated by comparing their ohmic characteristics with the ones ...Al electrodes are well known as ohmic contact electrodes for the PTC component , the influence of their thickness on final component properties was investigated by comparing their ohmic characteristics with the ones of InGa electrodes . After observing the Al paste physical and chemical behaviors during rising temperature by thermal analysis (DTA), the firing operation of Al electrodes could be divided into three main subsections: the temperature rising time (t-r), the peak firing temperature (T-p) and the hold time at peak firing temperature (t-h). The effects of these three parameters on final component properties were discussed in detail.展开更多
Manganese is an essential micronutrient for all organisms;however at high concentrations it has a toxic effect. Manganese toxicity is a serious constraint to crop cultivation since it is taken-up by plants and can eas...Manganese is an essential micronutrient for all organisms;however at high concentrations it has a toxic effect. Manganese toxicity is a serious constraint to crop cultivation since it is taken-up by plants and can easily be passed into the food chain again causing symptoms of Parkinson’s disease. A fully validated square-wave adsorptive cathodic stripping voltammetry method has been developed for determination of Mn (II) as a complex with 2-(5’-bromo-2’-pyridylazo) 5-diethylaminophenol in aqueous solutions using a carbon paste electrode (CPE) modified with montmorillonite-Na clay. The results showed that the modified CPE (90% (w/w) graphite powder and 10% (w/w) montmorillonite-Na clay) exhibited excellent electrochemical activity towards the investigated Mn (II) complex in acetate buffer of pH = 5.0. Factors affecting the performance of the modified carbon paste electrode and the sensitivity of the described square- wave stripping voltammetry method, including the electrode composition, concentration of ligand, pulse parameters and preconcentration conditions were examined. A detection limit (S/N = 3) of 0.015μg·L-1 (2.73 × 10-10 mol·L-1) Mn (II) was achieved when a preconcentration time of 240 s was applied. Insignificant interferences from various inorganic and organic species were estimated. The described square-wave adsorptive cathodic stripping voltammetry method coupled with the modified carbon paste electrode has been successfully applied to Mn (II) analysis in different water samples.展开更多
Recent interest in mobile-based healthcare has driven significant demands on researching non-contact electrodes for electrocardiogram (ECG)measurement. While the conductive gel achieves the requirement in making a goo...Recent interest in mobile-based healthcare has driven significant demands on researching non-contact electrodes for electrocardiogram (ECG)measurement. While the conductive gel achieves the requirement in making a good contact between the electrodes and skin, several problems appear. A gel-free,non-contact electrode based on capacitive coupling theory was provided in this paper,which was integrated on the print circuit board (PCB). The experimental results showed that clear ECG signals could be acquired in the laboratory conditions by coupling the electrodes to the chest of patients through cotton belts.展开更多
The electrode material is an important aspect for the efficiency and costs in the microbial fuel cells (MFCs). Enhancing of current production and bacteria attachment to the electrode are essential goals for developin...The electrode material is an important aspect for the efficiency and costs in the microbial fuel cells (MFCs). Enhancing of current production and bacteria attachment to the electrode are essential goals for developing the performance of MFCs. In this study, the role of the structural iron present in clays in enhancing the electron transfer of Shewanella oneidensis MR-1 was investigated. Two types of clay containing different amounts of iron situated in the octahedral sites were used to modify ITO (indium tin oxide) electrodes, namely nontronite NAu-1, and montmorillonite (Wyoming) SWy-1. Synthetic montmorillonite SYn-1 which is iron-free clay was used for comparison. The interaction between the bacterial cells and the clays was studied by potential-step chronoamperometry, cyclic voltammetry, confocal microscopy, and scanning electron microscopy (SEM). The obtained results showed that the current densities generated upon ITO electrode modification using the NAu-1 and SWy-1 iron-containing clays were 19 and 3 times higher than that produced using the bare ITO electrode. No current density was obtained when utilizing the synthetic montmorillonite SYn-1 clay. SEM and confocal microscopy observations confirmed the increased coverage percentage of the bacterial cells attached to the clay-modified electrodes compared to the bare ITO.展开更多
Robust and easy-to-handle solid-contact ion-selective electrodes (SC-ISEs) based on graphite paste have been developed for the potentiometric detection of NO-3 and NH+4 in environmental samples. Polypyrrole (PPy) has ...Robust and easy-to-handle solid-contact ion-selective electrodes (SC-ISEs) based on graphite paste have been developed for the potentiometric detection of NO-3 and NH+4 in environmental samples. Polypyrrole (PPy) has been used as intermediate layer and solid contact between the electron-conducting graphite paste substrate and the ion-conducting polyvinylchloride (PVC)-containing membrane with the immobilized ionophore. For the nitrate- and ammonium-selective electrodes, tridodecylmethylammonium nitrate (TDMA-NO3) and nonactin have been used as ion-complexing compounds, respectively. Both ISEs show nearly Nernstian response in the linear range from 10-5 mol/L to 10-1 mol/L with average slopes of >58 mV/decade. The ISEs possess short response times (<20 s).展开更多
Microneedle array(MNA)electrodes are an effective solution to achieve high-quality surface biopotential recording without the coordination of conductive gel and are thus very suitable for long-term wearable applicatio...Microneedle array(MNA)electrodes are an effective solution to achieve high-quality surface biopotential recording without the coordination of conductive gel and are thus very suitable for long-term wearable applications.Existing schemes are limited by flexibility,biosafety,and manufacturing costs,which create large barriers for wider applications.Here,we present a novel flexible MNA electrode that can simultaneously achieve flexibility of the substrate to fit a curved body surface,robustness of microneedles to penetrate the skin without fracture,and a simplified process to allow mass production.The compatibility with wearable wireless systems and the short preparation time of the electrodes significantly improves the comfort and convenience of electrophysiological recording.The normalized electrode–skin contact impedance reaches 0.98 kΩcm^(2)at 1 kHz and 1.50 kΩcm^(2)at 10 Hz,a record low value compared to previous reports and approximately 1/250 of the standard electrodes.The morphology,biosafety,and electrical/mechanical properties are fully characterized,and wearable recordings with a high signal-to-noise ratio and low motion artifacts are realized.The first reported clinical study of microneedle electrodes for surface electrophysiological monitoring was conducted in tens of healthy and sleep-disordered subjects with 44 nights of recording(over 8 h per night),providing substantial evidence that the electrodes can be leveraged to substitute for clinical standard electrodes.展开更多
The application of transparent conducting indium-tin-oxide (ITO) film as full front electrode replacing the conven- tional bus-bar metal electrode in III-V compound GalnP solar cell was proposed. A high-quality, non...The application of transparent conducting indium-tin-oxide (ITO) film as full front electrode replacing the conven- tional bus-bar metal electrode in III-V compound GalnP solar cell was proposed. A high-quality, non-rectifying contact between ITO and 10 nm N+-GaAs contact layer was formed, which is benefiting from a high carrier concentration of the terrilium-doped N+-GaAs layer, up to 2×10^19 cm^-3. A good device performance of the GalnP solar cell with the ITO electrode was observed. This result indicates a great potential of transparent conducting films in the future fabrication of larger area flexible III-V solar cell.展开更多
The objective of this work is to develop a novel methodology for determining real resistivity of conductive asphalt concrete based on two-electrode method.Due to an influence of contact resistance,the measured resisti...The objective of this work is to develop a novel methodology for determining real resistivity of conductive asphalt concrete based on two-electrode method.Due to an influence of contact resistance,the measured resistivity is always not equal to the real resistivity.To determine the real resistivity,a linear relationship of the measured resistivity,contact resistance and the real resistivity was established.Then experiments for six specimens with varying graphite contents were designed and performed to validate the formulation.Results of experiments demonstrate that the slope of the line represents contact resistance,and the intercept indicates the real resistivity.The effects of graphite content on contact resistance and real resistivity are also revealed.Finally,results show that the influence of contact resistance on accuracy of resisitvity measurement becomes more serious if graphite content is beyond 3%.Hence,it is the time to choose this novel methodology to determine the real resistivity of asphalt concrete by taking account of contact resistance.展开更多
In situ welding of a single ZnSe nanowire(NW)to an Au electrode has been successfully achieved by means of current-induced Joule heating.The parameter governing the welding of semiconductor NW to the metal electrode i...In situ welding of a single ZnSe nanowire(NW)to an Au electrode has been successfully achieved by means of current-induced Joule heating.The parameter governing the welding of semiconductor NW to the metal electrode is highly dominated by the current density at the Au-ZnSe NW(M-S)contact because current density at the M-S contact can change the temperature profile along the NW.The self-heating behaviors of the Au-ZnSe NW-Au(M-S-M)nanostructure can be changed from the electrical failure of the ZnSe NW to the melting of the Au electrode localized at the M-S contact when the current density at the M-S junction was adjusted to be larger than in the NW.Consequently,the self-welding is the current density-sensitive and controllable since the current density at the M-S contact can be controlled by adjusting the contact area between the NW and metal electrode.This controlled self-welding may have potential applications in the construction of a complex nanostructure and improvement of the thermal stability of the M-S contact as well as the enhanced performance of the nanodevices based on the M-S-M nanostructure.展开更多
The emerging field of neuroprosthetics is focused on design and implementation of neural prostheses to restore some of the lost neural functions. Remarkable progress has been reported at most bioelectronic levels—par...The emerging field of neuroprosthetics is focused on design and implementation of neural prostheses to restore some of the lost neural functions. Remarkable progress has been reported at most bioelectronic levels—particularly the various brain-machine interfaces (BMIs)—but the electrode-tissue contacts (ETCs) remain one of the major obstacles. The success of these BMIs relies on electrodes which are in contact with the neural tissue. Biological response to chronic implantation of Microelectrode arrays (MEAs) is an essential factor in determining a successful electrode design. By altering the material compositions and geometries of the arrays, fabrication techniques of MEAs insuring these ETCs try to obtain consistent recording signals from small groups of neurons without losing microstimulation capabilities, while maintaining low-impedance pathways for charge injection, high-charge transfer, and high-spatial resolution in recent years. So far, none of these attempts have led to a major breakthrough. Clearly, much work still needs to be done to accept a standard model of MEAs for clinical purposes. In this paper, we review different microfabrication techniques of MEAs with their advantages and drawbacks, and comment on various coating materials to enhance electrode performance. Then, we propose high-density, three-dimensional (3D), silicon-based MEAs using micromachining methods. The geometries that will be used include arrays of penetrating variable-height probes.展开更多
在轨道交通中,接触式验电器用于接触网停电作业中检测接触网是否停电,以确保作业地线的正确操作和检修工作安全进行。接触电极作为接触式验电器的重要组成部分,直接影响验电信号的采集。为研究接触式验电器的接触电极结构对验电结果的影...在轨道交通中,接触式验电器用于接触网停电作业中检测接触网是否停电,以确保作业地线的正确操作和检修工作安全进行。接触电极作为接触式验电器的重要组成部分,直接影响验电信号的采集。为研究接触式验电器的接触电极结构对验电结果的影响,以GSY-II型27.5 k V交流验电器和ZGD型1 500 V直流验电器为例,分析了其工作原理,并仿真研究了接触电极形状和长度的改变对验电结果的影响。仿真结果表明:对于交流验电器,改变接触电极形状为圆钩型和V型,内部电路的感应信号电压分别变化了3.1%和2.3%,该变化对验电结果影响较小;增加接触电极长度会提高感应信号电压,从而提高验电灵敏度。对于直流验电器,其接触电极形状和长度改变后,内部电路的信号电压保持不变,因此接触电极的形状和长度不影响验电结果。仿真结果为设计和优化验电器结构提供了参考依据。展开更多
The bearing behavior of suction caissons supporting offshore wind turbines under two-way cyclic lateral loading and dead load in clay was investigated with consideration of soil strength degradation and adhesive inter...The bearing behavior of suction caissons supporting offshore wind turbines under two-way cyclic lateral loading and dead load in clay was investigated with consideration of soil strength degradation and adhesive interface friction between caisson walls and heterogeneous clay using the finite-element package ABAQUS.An ABAQUS built-in user subroutine was programmed to calculate the adhesive interface friction between clay and caisson walls.The results of parametric studies showed that the degradation of bearing capacity could be aggravated by the decrease of the aspect ratio.The offset between the rotation point of the soil inside the caisson and the central axis of the caisson increased with the increasing vertical load and number of cycles.The linearly increasing strength profile and adhesive interface led to the formation of an inverted spoon failure zone inside the caisson.The settlement-rotation curves in each cycle moved downwards with increasing number of cycles due to the soil strength degradation.展开更多
基金the CSIRO Low Emissions Technologies Program for the support of this studythe financial support from the Australian Research Council(ARC)for the Future Fellowship(FT130101337)+4 种基金QUT core funding(QUT/322120-0301/07)supported by NSF MRI(1428992)U.S.-Egypt Science and Technology(S&T)Joint FundSDBoR R&D ProgramEDA University Center Program(ED18DEN3030025)。
文摘Perovskite-based photovoltaic materials have been attracting attention for their strikingly improved performance at converting sunlight into electricity.The beneficial and unique optoelectronic characteristics of perovskite structures enable researchers to achieve an incredibly remarkable power conversion efficiency.Flexible hybrid perovskite photovoltaics promise emerging applications in a myriad of optoelectronic and wearable/portable device applications owing to their inherent intriguing physicochemical and photophysical properties which enabled researchers to take forward advanced research in this growing field.Flexible perovskite photovoltaics have attracted significant attention owing to their fascinating material properties with combined merits of high efficiency,light-weight,flexibility,semitransparency,compatibility towards roll-to-roll printing,and large-area mass-scale production.Flexible perovskite-based solar cells comprise of 4 key components that include a flexible substrate,semi-transparent bottom contact electrode,perovskite(light absorber layer)and charge transport(electron/hole)layers and top(usually metal)electrode.Among these components,interfacial layers and contact electrodes play a pivotal role in influencing the overall photovoltaic performance.In this comprehensive review article,we focus on the current developments and latest progress achieved in perovskite photovoltaics concerning the charge selective transport layers/electrodes toward the fabrication of highly stable,efficient flexible devices.As a concluding remark,we briefly summarize the highlights of the review article and make recommendations for future outlook and investigation with perspectives on the perovskite-based optoelectronic functional devices that can be potentially utilized in smart wearable and portable devices.
基金supported by National Natural Science Foundation of China(Nos.U19A20105 and 52077182)。
文摘The relative motion of the electrodes is a typical feature of sliding electrical contact systems.The system fault caused by the arc is the key problem that restricts the service life of the sliding electrical contact system.In this paper,an arcing experimental platform that can accurately control the relative speed and distance of electrodes is built,and the influence of different electrode speeds and electrode distances on arc motion characteristics is explored.It is found that there are three different modes of arc root motion:single arc root motion mode,single and double arc roots alternating motion mode,and multiple arc roots motion mode.The physical process and influence mechanism of different arc root motion modes are further studied,and the corresponding relationship between arc root motion modes and electrode speed is revealed.In addition,to further explore the distribution characteristics of arc temperature and its influencing factors,an arc magnetohydrodynamic model under the relative motion of electrodes is established,and the variation law of arc temperature under the effect of different electrode speeds and electrode distances is summarized.Finally,the influence mechanism of electrode speed and electrode distance on arc temperature,arc root distance,and arc root speed is clarified.The research results enrich the research system of arc dynamic characteristics in the field of sliding electrical contact,and provide theoretical support for restraining arc erosion and improving the service life of the sliding electrical contact system.
基金National Natural Science Foundation ofChina,Grant/Award Numbers:51991340,51991342,52225206,92163205,52188101,62322402,62204012,52250398,51972022,52303362,62304019the National KeyResearch and Development Program of China,Grant/Award Numbers:2022YFA1203800,2022YFA1203803,2018YFA0703503,2023YFF1500400,2023YFF1500401+7 种基金the Overseas ExpertiseIntroduction Projects for DisciplineInnovation,Grant/Award Number:B14003the Frontier Cross ResearchProject of the Department of Chinese Academy of Sciences,Grant/AwardNumber:XK2023JSA001the Beijing NovaProgram,Grant/Award Numbers:20220484145,20230484478the YoungElite Scientists sponsorship program,Grant/Award Number:2022QNRC001the Fundamental Research Funds for the Central Universities,Grant/Award Number:FRF-06500207the Interdisciplinary Research Project forYoung Teachers of USTB,Grant/Award Numbers:FRF-TP-22-004C2,FRF-IDRY-21-008,FRF-TP-22-004A1,FRF-IDRY-22-016the State Key Lab for Advanced Metals and Materials,Grant/Award Number:2023-Z05the Special supportfrom the Postdoctoral Science Foundation,Grant/Award Number:8206400173。
文摘Metal–semiconductor contacts are crucial components in semiconductor devices.Ultrathin two-dimensional transition-metal dichalcogenide semiconductors can sustain transistor scaling for next-generation integrated circuits.However,their performance is often degraded by conventional metal deposition,which results in a high barrier due to chemical disorder and Fermi-level pinning(FLP).Although,transferring electrodes can address these issues,they are limited in achieving universal transfer of full-class metals due to strong adhesion between pre-deposited metals and substrates.Here,we propose a nanobelt-assisted transfer strategy that can avoid the adhesion limitation and enables the universal transfer of over 20 different types of electrodes.Our contacts obey the Schottky–Mott rule and exhibit a FLP of S=0.99.Both the electron and hole contacts show record-low Schottky barriers of 4.2 and 11.2 meV,respectively.As a demonstration,we construct a doping-free WSe_(2) inverter with these high-performance contacts,which exhibits a static power consumption of only 58 pW.This strategy provides a universal method of electrode preparation for building high-performance post-Moore electronic devices.
基金the funding support from the National Natural Science Foundation of China(22222902,22209062)the Natural Science Foundation of Jiangsu Province(BK20200047)+2 种基金the Natural Science Foundation of the Jiangsu Higher Education Institutions of China(22KJB150004)the Youth Talent Promotion Project of Jiangsu Association for Science and Technology of China(JSTJ-2022-023)Undergraduate Innovation and Entrepreneurship Training Program(202310320066Z)。
文摘The utilization of solid-state electrolytes(SSEs)presents a promising solution to the issues of safety concern and shuttle effect in Li–S batteries,which has garnered significant interest recently.However,the high interfacial impedances existing between the SSEs and the electrodes(both lithium anodes and sulfur cathodes)hinder the charge transfer and intensify the uneven deposition of lithium,which ultimately result in insufficient capacity utilization and poor cycling stability.Hence,the reduction of interfacial resistance between SSEs and electrodes is of paramount importance in the pursuit of efficacious solid-state batteries.In this review,we focus on the experimental strategies employed to enhance the interfacial contact between SSEs and electrodes,and summarize recent progresses of their applications in solidstate Li–S batteries.Moreover,the challenges and perspectives of rational interfacial design in practical solid-state Li–S batteries are outlined as well.We expect that this review will provide new insights into the further technique development and practical applications of solid-state lithium batteries.
文摘Al electrodes are well known as ohmic contact electrodes for the PTC component , the influence of their thickness on final component properties was investigated by comparing their ohmic characteristics with the ones of InGa electrodes . After observing the Al paste physical and chemical behaviors during rising temperature by thermal analysis (DTA), the firing operation of Al electrodes could be divided into three main subsections: the temperature rising time (t-r), the peak firing temperature (T-p) and the hold time at peak firing temperature (t-h). The effects of these three parameters on final component properties were discussed in detail.
文摘Manganese is an essential micronutrient for all organisms;however at high concentrations it has a toxic effect. Manganese toxicity is a serious constraint to crop cultivation since it is taken-up by plants and can easily be passed into the food chain again causing symptoms of Parkinson’s disease. A fully validated square-wave adsorptive cathodic stripping voltammetry method has been developed for determination of Mn (II) as a complex with 2-(5’-bromo-2’-pyridylazo) 5-diethylaminophenol in aqueous solutions using a carbon paste electrode (CPE) modified with montmorillonite-Na clay. The results showed that the modified CPE (90% (w/w) graphite powder and 10% (w/w) montmorillonite-Na clay) exhibited excellent electrochemical activity towards the investigated Mn (II) complex in acetate buffer of pH = 5.0. Factors affecting the performance of the modified carbon paste electrode and the sensitivity of the described square- wave stripping voltammetry method, including the electrode composition, concentration of ligand, pulse parameters and preconcentration conditions were examined. A detection limit (S/N = 3) of 0.015μg·L-1 (2.73 × 10-10 mol·L-1) Mn (II) was achieved when a preconcentration time of 240 s was applied. Insignificant interferences from various inorganic and organic species were estimated. The described square-wave adsorptive cathodic stripping voltammetry method coupled with the modified carbon paste electrode has been successfully applied to Mn (II) analysis in different water samples.
文摘Recent interest in mobile-based healthcare has driven significant demands on researching non-contact electrodes for electrocardiogram (ECG)measurement. While the conductive gel achieves the requirement in making a good contact between the electrodes and skin, several problems appear. A gel-free,non-contact electrode based on capacitive coupling theory was provided in this paper,which was integrated on the print circuit board (PCB). The experimental results showed that clear ECG signals could be acquired in the laboratory conditions by coupling the electrodes to the chest of patients through cotton belts.
文摘The electrode material is an important aspect for the efficiency and costs in the microbial fuel cells (MFCs). Enhancing of current production and bacteria attachment to the electrode are essential goals for developing the performance of MFCs. In this study, the role of the structural iron present in clays in enhancing the electron transfer of Shewanella oneidensis MR-1 was investigated. Two types of clay containing different amounts of iron situated in the octahedral sites were used to modify ITO (indium tin oxide) electrodes, namely nontronite NAu-1, and montmorillonite (Wyoming) SWy-1. Synthetic montmorillonite SYn-1 which is iron-free clay was used for comparison. The interaction between the bacterial cells and the clays was studied by potential-step chronoamperometry, cyclic voltammetry, confocal microscopy, and scanning electron microscopy (SEM). The obtained results showed that the current densities generated upon ITO electrode modification using the NAu-1 and SWy-1 iron-containing clays were 19 and 3 times higher than that produced using the bare ITO electrode. No current density was obtained when utilizing the synthetic montmorillonite SYn-1 clay. SEM and confocal microscopy observations confirmed the increased coverage percentage of the bacterial cells attached to the clay-modified electrodes compared to the bare ITO.
文摘Robust and easy-to-handle solid-contact ion-selective electrodes (SC-ISEs) based on graphite paste have been developed for the potentiometric detection of NO-3 and NH+4 in environmental samples. Polypyrrole (PPy) has been used as intermediate layer and solid contact between the electron-conducting graphite paste substrate and the ion-conducting polyvinylchloride (PVC)-containing membrane with the immobilized ionophore. For the nitrate- and ammonium-selective electrodes, tridodecylmethylammonium nitrate (TDMA-NO3) and nonactin have been used as ion-complexing compounds, respectively. Both ISEs show nearly Nernstian response in the linear range from 10-5 mol/L to 10-1 mol/L with average slopes of >58 mV/decade. The ISEs possess short response times (<20 s).
基金supported by the China Capital Health Research and Development of Special (No. 2018-14111)the National Natural Science Foundation of China (grant No. 62004007 and No. 82027805)the China Postdoctoral Science Foundation Grant (No. 2021M700258)
文摘Microneedle array(MNA)electrodes are an effective solution to achieve high-quality surface biopotential recording without the coordination of conductive gel and are thus very suitable for long-term wearable applications.Existing schemes are limited by flexibility,biosafety,and manufacturing costs,which create large barriers for wider applications.Here,we present a novel flexible MNA electrode that can simultaneously achieve flexibility of the substrate to fit a curved body surface,robustness of microneedles to penetrate the skin without fracture,and a simplified process to allow mass production.The compatibility with wearable wireless systems and the short preparation time of the electrodes significantly improves the comfort and convenience of electrophysiological recording.The normalized electrode–skin contact impedance reaches 0.98 kΩcm^(2)at 1 kHz and 1.50 kΩcm^(2)at 10 Hz,a record low value compared to previous reports and approximately 1/250 of the standard electrodes.The morphology,biosafety,and electrical/mechanical properties are fully characterized,and wearable recordings with a high signal-to-noise ratio and low motion artifacts are realized.The first reported clinical study of microneedle electrodes for surface electrophysiological monitoring was conducted in tens of healthy and sleep-disordered subjects with 44 nights of recording(over 8 h per night),providing substantial evidence that the electrodes can be leveraged to substitute for clinical standard electrodes.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61534008,61376081,and 61404157)the Application Foundation of Suzhou,China(Grant No.SYG201437)
文摘The application of transparent conducting indium-tin-oxide (ITO) film as full front electrode replacing the conven- tional bus-bar metal electrode in III-V compound GalnP solar cell was proposed. A high-quality, non-rectifying contact between ITO and 10 nm N+-GaAs contact layer was formed, which is benefiting from a high carrier concentration of the terrilium-doped N+-GaAs layer, up to 2×10^19 cm^-3. A good device performance of the GalnP solar cell with the ITO electrode was observed. This result indicates a great potential of transparent conducting films in the future fabrication of larger area flexible III-V solar cell.
基金Project(51178348)supported by the National Natural Science Foundation of China
文摘The objective of this work is to develop a novel methodology for determining real resistivity of conductive asphalt concrete based on two-electrode method.Due to an influence of contact resistance,the measured resistivity is always not equal to the real resistivity.To determine the real resistivity,a linear relationship of the measured resistivity,contact resistance and the real resistivity was established.Then experiments for six specimens with varying graphite contents were designed and performed to validate the formulation.Results of experiments demonstrate that the slope of the line represents contact resistance,and the intercept indicates the real resistivity.The effects of graphite content on contact resistance and real resistivity are also revealed.Finally,results show that the influence of contact resistance on accuracy of resisitvity measurement becomes more serious if graphite content is beyond 3%.Hence,it is the time to choose this novel methodology to determine the real resistivity of asphalt concrete by taking account of contact resistance.
基金Supported by the National Natural Science Foundation of China under Grant Nos 60976078 and 11274365Young Scholar Program of Hunan Agricultural University under Grant No 12QN05.
文摘In situ welding of a single ZnSe nanowire(NW)to an Au electrode has been successfully achieved by means of current-induced Joule heating.The parameter governing the welding of semiconductor NW to the metal electrode is highly dominated by the current density at the Au-ZnSe NW(M-S)contact because current density at the M-S contact can change the temperature profile along the NW.The self-heating behaviors of the Au-ZnSe NW-Au(M-S-M)nanostructure can be changed from the electrical failure of the ZnSe NW to the melting of the Au electrode localized at the M-S contact when the current density at the M-S junction was adjusted to be larger than in the NW.Consequently,the self-welding is the current density-sensitive and controllable since the current density at the M-S contact can be controlled by adjusting the contact area between the NW and metal electrode.This controlled self-welding may have potential applications in the construction of a complex nanostructure and improvement of the thermal stability of the M-S contact as well as the enhanced performance of the nanodevices based on the M-S-M nanostructure.
文摘The emerging field of neuroprosthetics is focused on design and implementation of neural prostheses to restore some of the lost neural functions. Remarkable progress has been reported at most bioelectronic levels—particularly the various brain-machine interfaces (BMIs)—but the electrode-tissue contacts (ETCs) remain one of the major obstacles. The success of these BMIs relies on electrodes which are in contact with the neural tissue. Biological response to chronic implantation of Microelectrode arrays (MEAs) is an essential factor in determining a successful electrode design. By altering the material compositions and geometries of the arrays, fabrication techniques of MEAs insuring these ETCs try to obtain consistent recording signals from small groups of neurons without losing microstimulation capabilities, while maintaining low-impedance pathways for charge injection, high-charge transfer, and high-spatial resolution in recent years. So far, none of these attempts have led to a major breakthrough. Clearly, much work still needs to be done to accept a standard model of MEAs for clinical purposes. In this paper, we review different microfabrication techniques of MEAs with their advantages and drawbacks, and comment on various coating materials to enhance electrode performance. Then, we propose high-density, three-dimensional (3D), silicon-based MEAs using micromachining methods. The geometries that will be used include arrays of penetrating variable-height probes.
文摘在轨道交通中,接触式验电器用于接触网停电作业中检测接触网是否停电,以确保作业地线的正确操作和检修工作安全进行。接触电极作为接触式验电器的重要组成部分,直接影响验电信号的采集。为研究接触式验电器的接触电极结构对验电结果的影响,以GSY-II型27.5 k V交流验电器和ZGD型1 500 V直流验电器为例,分析了其工作原理,并仿真研究了接触电极形状和长度的改变对验电结果的影响。仿真结果表明:对于交流验电器,改变接触电极形状为圆钩型和V型,内部电路的感应信号电压分别变化了3.1%和2.3%,该变化对验电结果影响较小;增加接触电极长度会提高感应信号电压,从而提高验电灵敏度。对于直流验电器,其接触电极形状和长度改变后,内部电路的信号电压保持不变,因此接触电极的形状和长度不影响验电结果。仿真结果为设计和优化验电器结构提供了参考依据。
基金supported by the National Natural Science Foundation of China(Grant No.52078483).
文摘The bearing behavior of suction caissons supporting offshore wind turbines under two-way cyclic lateral loading and dead load in clay was investigated with consideration of soil strength degradation and adhesive interface friction between caisson walls and heterogeneous clay using the finite-element package ABAQUS.An ABAQUS built-in user subroutine was programmed to calculate the adhesive interface friction between clay and caisson walls.The results of parametric studies showed that the degradation of bearing capacity could be aggravated by the decrease of the aspect ratio.The offset between the rotation point of the soil inside the caisson and the central axis of the caisson increased with the increasing vertical load and number of cycles.The linearly increasing strength profile and adhesive interface led to the formation of an inverted spoon failure zone inside the caisson.The settlement-rotation curves in each cycle moved downwards with increasing number of cycles due to the soil strength degradation.