In recent years, target tracking has been considered one of the most important applications of wireless sensornetwork (WSN). Optimizing target tracking performance and prolonging network lifetime are two equally criti...In recent years, target tracking has been considered one of the most important applications of wireless sensornetwork (WSN). Optimizing target tracking performance and prolonging network lifetime are two equally criticalobjectives in this scenario. The existing mechanisms still have weaknesses in balancing the two demands. Theproposed heuristic multi-node collaborative scheduling mechanism (HMNCS) comprises cluster head (CH)election, pre-selection, and task set selectionmechanisms, where the latter two kinds of selections forma two-layerselection mechanism. The CH election innovatively introduces the movement trend of the target and establishesa scoring mechanism to determine the optimal CH, which can delay the CH rotation and thus reduce energyconsumption. The pre-selection mechanism adaptively filters out suitable nodes as the candidate task set to applyfor tracking tasks, which can reduce the application consumption and the overhead of the following task setselection. Finally, the task node selection is mathematically transformed into an optimization problem and thegenetic algorithm is adopted to form a final task set in the task set selection mechanism. Simulation results showthat HMNCS outperforms other compared mechanisms in the tracking accuracy and the network lifetime.展开更多
Beetle wings are very specialized flight organs consisting of the veins and membranes.Therefore it is necessary from a bionic view to investigate the material properties of a beetle wing experimentally.In the present ...Beetle wings are very specialized flight organs consisting of the veins and membranes.Therefore it is necessary from a bionic view to investigate the material properties of a beetle wing experimentally.In the present study,we have used a Digital Image Correlation (DIC) technique to measure the elastic modulus of a beetle wing membrane.Specimens were prepared by carefully cutting a beetle hind wing into 3.0 mm by 7.0 mm segments (the gage length was 5 mm).We used a scanning electron microscope for a precise measurement of the thickness of the beetle wing membrane.The specimen was attached to a designed fixture to induce a uniform displacement by means of a micromanipulator.We used an ARAMISTM system based on the digital image correlation technique to measure the corresponding displacement of a specimen.The thickness of the beetle wing varied at different points of the membrane.The elastic modulus differed in relation to the membrane arrangement showing a structural anisotropy;the elastic modulus in the chordwise direction is approximately 2.65 GPa,which is three times larger than the elastic modulus in the spanwise direction of 0.84 GPa.As a result,the digital image correlation-based ARAMIS system was suc- cessfully used to measure the elastic modulus of a beetle wing.In addition to membrane's elastic modulus,we considered the Poisson's ratio of the membrane and measured the elastic modulus of a vein using an Instron universal tensile machine.The result reveals the Poisson's ratio is nearly zero and the elastic modulus of a vein is about 11 GPa.展开更多
In this work, a three-dimensional （3D） Computational Fluid Dynamics （CFD） model was built to simulate the tail fin motion of a fish robot actuated by a piezoceramic composite actuator, and to determine the maximum...In this work, a three-dimensional （3D） Computational Fluid Dynamics （CFD） model was built to simulate the tail fin motion of a fish robot actuated by a piezoceramic composite actuator, and to determine the maximum thrust tail-beat frequency. A simulation of the tail fin at a tail-beat frequency was performed to confirm measured thrust data from a previous study. The computed and measured thrusts were in good agreement. A series of thrust simulations were conducted for various tail-beat frequencies to confirm the maximum thrust frequency that was obtained from thrust measurements in the previous study. The largest thrust was calculated at a tail-beat frequency of 3.7 Hz and vortices around the tail were fully separated. The calculated maximum thrust tail-beat frequency was in good agreement with the measured frequency. Flow characteristics during tail fin motion were examined to explain why the largest thrust occurred at this particular tail-beat frequency.展开更多
Peripheral nerve injuries with a poor prognosis are common.Evening primrose oil（EPO） has beneficial biological effects and immunomodulatory properties.Since electrical activity plays a major role in neural regenerat...Peripheral nerve injuries with a poor prognosis are common.Evening primrose oil（EPO） has beneficial biological effects and immunomodulatory properties.Since electrical activity plays a major role in neural regeneration,the present study investigated the effects of electrical stimulation（ES）,combined with evening primrose oil（EPO）,on sciatic nerve function after a crush injury in rats.In anesthetized rats,the sciatic nerve was crushed using small haemostatic forceps followed by ES and/or EPO treatment for 4 weeks.Functional recovery of the sciatic nerve was assessed using the sciatic functional index.Histopathological changes of gastrocnemius muscle atrophy were investigated by light microscopy.Electrophysiological changes were assessed by the nerve conduction velocity of sciatic nerves.Immunohistochemistry was used to determine the remyelination of the sciatic nerve following the interventions.EPO ＋ ES,EPO,and ES obviously improved sciatic nerve function assessed by the sciatic functional index and nerve conduction velocity of the sciatic nerve at 28 days after operation.Expression of the peripheral nerve remyelination marker,protein zero（P0）,was increased in the treatment groups at 28 days after operation.Muscle atrophy severity was decreased significantly while the nerve conduction velocity was increased significantly in rats with sciatic nerve injury in the injury ＋ EPO ＋ ES group than in the EPO or ES group.Totally speaking,the combined use of EPO and ES may produce an improving effect on the function of sciatic nerves injured by a crush.The increased expression of P0 may have contributed to improving the functional effects of combination therapy with EPO and ES as well as the electrophysiological and histopathological features of the injured peripheral nerve.展开更多
Ionization efficiency is an important factor for ion sources in mass spectrometry and ion mobility spectrometry.Using helium as the discharge gas,acetone as the sample,and high-field asymmetric ion mobility spectrome...Ionization efficiency is an important factor for ion sources in mass spectrometry and ion mobility spectrometry.Using helium as the discharge gas,acetone as the sample,and high-field asymmetric ion mobility spectrometry（FAIMS） as the ion detection method,this work investigates in detail the effects of discharge parameters on the efficiency of ambient metastableinduced desorption ionization（AMDI） at atmospheric pressure.The results indicate that the discharge power and gas flow rate are both significantly correlated with the ionization efficiency.Specifically,an increase in the applied discharge power leads to a rapid increase in the ionization efficiency,which gradually reaches equilibrium due to ion saturation.Moreover,when the discharge voltage is fixed at 2.1 kV,a maximum efficiency can be achieved at the flow rate of 9.0 m/s.This study provides a foundation for the design and application of AMDI for on-line detection with mass spectrometry and ion mobility spectrometry.展开更多
Electroplated Cu,which can be compatible with integrated circuit technology and large-scale silicon wafers,is explored as a substrate to synthesize graphene domains by ambient-pressure chemical vapor deposition.Hexago...Electroplated Cu,which can be compatible with integrated circuit technology and large-scale silicon wafers,is explored as a substrate to synthesize graphene domains by ambient-pressure chemical vapor deposition.Hexagonal single crystal domains of graphene are synthesized on electroplated Cu under dilute methane gas flow.Scanning electron microscopy images of graphene domains grown on electroplated Cu indicate that the domain size is time-dependent,and the domains can cross Cu grain boundaries and are distributed more uniformly on electroplated Cu surface than those grown on Cu foil.展开更多
Amyloid beta oligomers(AβO)are pivotal in Alzheimer’s Disease(AD),cleared by microglia cells,as immune cells in the brain.Microglia cells exposed to AβO are involved with migration,apoptosis,phagocytosis,and activa...Amyloid beta oligomers(AβO)are pivotal in Alzheimer’s Disease(AD),cleared by microglia cells,as immune cells in the brain.Microglia cells exposed to AβO are involved with migration,apoptosis,phagocytosis,and activated microglial receptors through AβO,impacting cellular mechanobiological characteristics such as microglial adhesion strength to the underlying substrate.Herein,a label-free microfluidic device was used to detect advancing AD conditions with increasing AβO concentrations on microglia BV2 cells by quantitatively comparing the cell-substrate adhesion.The microfluidic device,acting as an AD model,comprises a single channel,which functions as a cell adhesion assay.To assess cell-substrate adhesion under different AβO concentrations of 1μM,2.5μM,and 5μM,the number of the cells attached to the substrate was counted by real-time microscopy when the cells were under the flow shear stress of 3 Pa and 7.5 Pa corresponding to Reynolds number(Re)of 10 and 25,respectively.The data showed that quantifying the cell-substrate adhesion using the microfluidic device could successfully identify conditions of advancing AβO concentrations.Our findings indicated that the increased incubation time with AβO caused reduced cell-substrate adhesion strength.Additionally,increased AβO concentration was another factor that weakened microglial interaction with the substrate.The quantification of cell-substrate adhesion using 3 Pa compared to 7.5 Pa clearly demonstrated advancing AβO in AD.This study using the chip provides an AD model for a deeper understanding mechanobiological behaviors of microglia exposed to AβO corresponding to diagnosed AD conditions under an in vitro microenvironment.展开更多
Grayscale structured surfaces with nanometer-scale features are used in a growing number of applications in optics and fluidics.Thermal scanning probe lithography achieves a lateral resolution below 10 nm and a vertic...Grayscale structured surfaces with nanometer-scale features are used in a growing number of applications in optics and fluidics.Thermal scanning probe lithography achieves a lateral resolution below 10 nm and a vertical resolution below 1 nm,but its maximum depth in polymers is limited.Here,we present an innovative combination of nanowriting in thermal resist and plasma dry etching with substrate cooling,which achieves up to 10-fold amplification of polymer nanopatterns into SiO_(2) without proportionally increasing surface roughness.Sinusoidal nanopatterns in SiO_(2) with 400 nm pitch and 150 nm depth are fabricated free of shape distortion after dry etching.To exemplify the possible applications of the proposed method,grayscale dielectric nanostructures are used for scalable manufacturing through nanoimprint lithography and for strain nanoengineering of 2D materials.Such a method for aspect ratio amplification and smooth grayscale nanopatterning has the potential to find application in the fabrication of photonic and nanoelectronic devices.展开更多
In the past decade, micro-electromechanical systems （MEMS）-based thermoelectric infrared （IR） sensors have received considerable attention because of the advances in micromachining technology. This paper presents ...In the past decade, micro-electromechanical systems （MEMS）-based thermoelectric infrared （IR） sensors have received considerable attention because of the advances in micromachining technology. This paper presents a review of MEMS-based thermoelectric IR sensors. The first part describes the physics of the device and discusses the figures of merit. The second part discusses the sensing materials, thermal isolation micro- structures, absorber designs, and packaging methods for these sensors and provides examples. Moreover, the status of sensor implementation technology is examined from a historical perspective by presenting findings from the early years to the most recent findings.展开更多
A moireis an interference pattern that appears when two different periodic structures are overlaid.The image created is extremely sensitive to small variations in the original layers and is thus very interesting for a...A moireis an interference pattern that appears when two different periodic structures are overlaid.The image created is extremely sensitive to small variations in the original layers and is thus very interesting for anti-counterfeit protection.We present a microfabricated 1D moire enabling complex high-resolution patterns as a significantly improved security feature that cannot be reproduced using standard printing methods.Furthermore,we demonstrate,theoretically and experimentally,that a microscopic deviation from the original design results in a macroscopic variation in the moire that is clearly visible to the naked eye.The record resolution achieved in the elements fabricated and the increased design freedom,make these high-resolution moires excellent candidates for a variety of visually appealing security applications.展开更多
Fundamental aspects and state-of-the-art results of thermal scanning probe lithography(t-SPL)are reviewed here.t-SPL is an emerging direct-write nanolithography method with many unique properties which enable original...Fundamental aspects and state-of-the-art results of thermal scanning probe lithography(t-SPL)are reviewed here.t-SPL is an emerging direct-write nanolithography method with many unique properties which enable original or improved nano-patterning in application fields ranging from quantum technologies to material science.In particular,ultrafast and highly localized thermal processing of surfaces can be achieved through the sharp heated tip in t-SPL to generate high-resolution patterns.We investigate t-SPL as a means of generating three types of material interaction:removal,conversion,and addition.Each of these categories is illustrated with process parameters and application examples,as well as their respective opportunities and challenges.Our intention is to provide a knowledge base of t-SPL capabilities and current limitations and to guide nanoengineers to the best-fitting approach of t-SPL for their challenges in nanofabrication or material science.Many potential applications of nanoscale modifications with thermal probes still wait to be explored,in particular when one can utilize the inherently ultrahigh heating and cooling rates.展开更多
With the rapid development of the Internet of Things(loT)and the emergence of 5G,traditional silicon-based electronics no Ion ger fully meet market dema nds such as nonplanar application scenarios due to mechanical mi...With the rapid development of the Internet of Things(loT)and the emergence of 5G,traditional silicon-based electronics no Ion ger fully meet market dema nds such as nonplanar application scenarios due to mechanical mismatch.This provides unprecedented opportunities for flexible electronics that bypass the physical rigidity through the introduction of flexible materials.In recent decades,biological materials with outstanding biocompatibility and biodegradability,which are considered some of the most promising candidates for next-generation flexible electronics,have received increasing attention,e.g.,silk fibroin,cellulose,pectin,chitosan,and melanin.Among them,silk fibroin presents greater superiorities in biocompatibility and biodegradability,and moreover,it also possesses a variety of attractive properties,such as adjustable water solubility,remarkable optical transmittance,high mechanical robustness,light weight,and ease of processing,which are partially or even completely lacking in other biological materials.Therefore,silk fibroin has been widely used as fundamental components for the construction of biocompatible flexible electronics,particularly for wearable and implantable devices.Furthermore,in recent years,more attention has been paid to the investigation of the functional characteristics of silk fibroin;such as the dielectric properties,piezoelectric properties,strong ability to lose electrons,and sensitivity to environmental variables.Here,this paper not only reviews the preparation technologies for various forms of silk fibroin and the recent progress in the use of silk fibroin as a fundamental material but also focuses on the recent advaneed works in which silk fibroin serves as functional components.Additi on ally,the challenges and future development of silk fibroin-based flexible electronics are summarized.展开更多
The heat conduction and infrared absorption properties of the dielectric film have a great influence on the thermopile performance.Thinning the dielectric film,reducing its contact area with the silicon substrate,or a...The heat conduction and infrared absorption properties of the dielectric film have a great influence on the thermopile performance.Thinning the dielectric film,reducing its contact area with the silicon substrate,or adding high-absorptivity nano materials has been proven to be effective in improving thermopiles.However,these methods may result in a decrease in the structural mechanical strength and in creases in the fabrication complexity and cost.In this work,a new performa nce-enha ncement strategy for thermopiles by simultaneously con trolling the heat conduction and infrared absorption with a TExtured Dielectric(TEDI)film is developed and presented.The TEDI film is formed in situ by a simple hard-molding process that is compatible with the fabrication of traditional thermopiles.Compared to the control FLat Dielectric(FLDI)film,the intrinsic thermal conductance of the TEDI film can be reduced by〜18-30%,while the in fra red absorptio n can be increased by-7-13%.Corresp on dingly,the responsivity and detectivity of the fabricated TEDI film-based thermopile can be significantly enhanced by〜38-64%.An optimized TEDI film-based thermopile has achieved a responsivity of 156.89 V-W_1 and a detectivity of 2.16×10^(8)cm-Hz^(1/2)·W^(-1),while the response time constant can remain<12 ms.These results exhibit the great potential of using this strategy to develop high-performance thermopiles and enhance other sensors with heat transfer and/or infrared absorption mechanisms.展开更多
基金the Project Program of Science and Technology on Micro-System Laboratory,No.6142804220101.
文摘In recent years, target tracking has been considered one of the most important applications of wireless sensornetwork (WSN). Optimizing target tracking performance and prolonging network lifetime are two equally criticalobjectives in this scenario. The existing mechanisms still have weaknesses in balancing the two demands. Theproposed heuristic multi-node collaborative scheduling mechanism (HMNCS) comprises cluster head (CH)election, pre-selection, and task set selectionmechanisms, where the latter two kinds of selections forma two-layerselection mechanism. The CH election innovatively introduces the movement trend of the target and establishesa scoring mechanism to determine the optimal CH, which can delay the CH rotation and thus reduce energyconsumption. The pre-selection mechanism adaptively filters out suitable nodes as the candidate task set to applyfor tracking tasks, which can reduce the application consumption and the overhead of the following task setselection. Finally, the task node selection is mathematically transformed into an optimization problem and thegenetic algorithm is adopted to form a final task set in the task set selection mechanism. Simulation results showthat HMNCS outperforms other compared mechanisms in the tracking accuracy and the network lifetime.
基金supported by the Basic Science Research Program through the National Research Foundation of Korea (NRF)the Ministry of Education, Science and Technology (Grant number: 2009-0083068)
文摘Beetle wings are very specialized flight organs consisting of the veins and membranes.Therefore it is necessary from a bionic view to investigate the material properties of a beetle wing experimentally.In the present study,we have used a Digital Image Correlation (DIC) technique to measure the elastic modulus of a beetle wing membrane.Specimens were prepared by carefully cutting a beetle hind wing into 3.0 mm by 7.0 mm segments (the gage length was 5 mm).We used a scanning electron microscope for a precise measurement of the thickness of the beetle wing membrane.The specimen was attached to a designed fixture to induce a uniform displacement by means of a micromanipulator.We used an ARAMISTM system based on the digital image correlation technique to measure the corresponding displacement of a specimen.The thickness of the beetle wing varied at different points of the membrane.The elastic modulus differed in relation to the membrane arrangement showing a structural anisotropy;the elastic modulus in the chordwise direction is approximately 2.65 GPa,which is three times larger than the elastic modulus in the spanwise direction of 0.84 GPa.As a result,the digital image correlation-based ARAMIS system was suc- cessfully used to measure the elastic modulus of a beetle wing.In addition to membrane's elastic modulus,we considered the Poisson's ratio of the membrane and measured the elastic modulus of a vein using an Instron universal tensile machine.The result reveals the Poisson's ratio is nearly zero and the elastic modulus of a vein is about 11 GPa.
文摘In this work, a three-dimensional （3D） Computational Fluid Dynamics （CFD） model was built to simulate the tail fin motion of a fish robot actuated by a piezoceramic composite actuator, and to determine the maximum thrust tail-beat frequency. A simulation of the tail fin at a tail-beat frequency was performed to confirm measured thrust data from a previous study. The computed and measured thrusts were in good agreement. A series of thrust simulations were conducted for various tail-beat frequencies to confirm the maximum thrust frequency that was obtained from thrust measurements in the previous study. The largest thrust was calculated at a tail-beat frequency of 3.7 Hz and vortices around the tail were fully separated. The calculated maximum thrust tail-beat frequency was in good agreement with the measured frequency. Flow characteristics during tail fin motion were examined to explain why the largest thrust occurred at this particular tail-beat frequency.
基金financially supported by the Neuroscience Research Center of the Tabriz University of Medical Sciences,Tabriz,Iran
文摘Peripheral nerve injuries with a poor prognosis are common.Evening primrose oil（EPO） has beneficial biological effects and immunomodulatory properties.Since electrical activity plays a major role in neural regeneration,the present study investigated the effects of electrical stimulation（ES）,combined with evening primrose oil（EPO）,on sciatic nerve function after a crush injury in rats.In anesthetized rats,the sciatic nerve was crushed using small haemostatic forceps followed by ES and/or EPO treatment for 4 weeks.Functional recovery of the sciatic nerve was assessed using the sciatic functional index.Histopathological changes of gastrocnemius muscle atrophy were investigated by light microscopy.Electrophysiological changes were assessed by the nerve conduction velocity of sciatic nerves.Immunohistochemistry was used to determine the remyelination of the sciatic nerve following the interventions.EPO ＋ ES,EPO,and ES obviously improved sciatic nerve function assessed by the sciatic functional index and nerve conduction velocity of the sciatic nerve at 28 days after operation.Expression of the peripheral nerve remyelination marker,protein zero（P0）,was increased in the treatment groups at 28 days after operation.Muscle atrophy severity was decreased significantly while the nerve conduction velocity was increased significantly in rats with sciatic nerve injury in the injury ＋ EPO ＋ ES group than in the EPO or ES group.Totally speaking,the combined use of EPO and ES may produce an improving effect on the function of sciatic nerves injured by a crush.The increased expression of P0 may have contributed to improving the functional effects of combination therapy with EPO and ES as well as the electrophysiological and histopathological features of the injured peripheral nerve.
基金supported by National Natural Science Foundation of China(No.61374016)the Changzhou Science and Technology Support Program,China(No.CE20120081)the External Cooperation Program of Chinese Academy of Sciences(No.GJHZ1218)
文摘Ionization efficiency is an important factor for ion sources in mass spectrometry and ion mobility spectrometry.Using helium as the discharge gas,acetone as the sample,and high-field asymmetric ion mobility spectrometry（FAIMS） as the ion detection method,this work investigates in detail the effects of discharge parameters on the efficiency of ambient metastableinduced desorption ionization（AMDI） at atmospheric pressure.The results indicate that the discharge power and gas flow rate are both significantly correlated with the ionization efficiency.Specifically,an increase in the applied discharge power leads to a rapid increase in the ionization efficiency,which gradually reaches equilibrium due to ion saturation.Moreover,when the discharge voltage is fixed at 2.1 kV,a maximum efficiency can be achieved at the flow rate of 9.0 m/s.This study provides a foundation for the design and application of AMDI for on-line detection with mass spectrometry and ion mobility spectrometry.
基金Supported by the National Science and Technology Specific Projects(No 2011ZX02707)the National Basic Research Program of China(No 2011CB309501)+1 种基金the Foundation for Innovative Research Groups of the National Natural Science Foundation of China under Grant(No 61021064)the National Natural Science Foundation of China(Nos 60936001,81201358 and 91123037).
文摘Electroplated Cu,which can be compatible with integrated circuit technology and large-scale silicon wafers,is explored as a substrate to synthesize graphene domains by ambient-pressure chemical vapor deposition.Hexagonal single crystal domains of graphene are synthesized on electroplated Cu under dilute methane gas flow.Scanning electron microscopy images of graphene domains grown on electroplated Cu indicate that the domain size is time-dependent,and the domains can cross Cu grain boundaries and are distributed more uniformly on electroplated Cu surface than those grown on Cu foil.
文摘Amyloid beta oligomers(AβO)are pivotal in Alzheimer’s Disease(AD),cleared by microglia cells,as immune cells in the brain.Microglia cells exposed to AβO are involved with migration,apoptosis,phagocytosis,and activated microglial receptors through AβO,impacting cellular mechanobiological characteristics such as microglial adhesion strength to the underlying substrate.Herein,a label-free microfluidic device was used to detect advancing AD conditions with increasing AβO concentrations on microglia BV2 cells by quantitatively comparing the cell-substrate adhesion.The microfluidic device,acting as an AD model,comprises a single channel,which functions as a cell adhesion assay.To assess cell-substrate adhesion under different AβO concentrations of 1μM,2.5μM,and 5μM,the number of the cells attached to the substrate was counted by real-time microscopy when the cells were under the flow shear stress of 3 Pa and 7.5 Pa corresponding to Reynolds number(Re)of 10 and 25,respectively.The data showed that quantifying the cell-substrate adhesion using the microfluidic device could successfully identify conditions of advancing AβO concentrations.Our findings indicated that the increased incubation time with AβO caused reduced cell-substrate adhesion strength.Additionally,increased AβO concentration was another factor that weakened microglial interaction with the substrate.The quantification of cell-substrate adhesion using 3 Pa compared to 7.5 Pa clearly demonstrated advancing AβO in AD.This study using the chip provides an AD model for a deeper understanding mechanobiological behaviors of microglia exposed to AβO corresponding to diagnosed AD conditions under an in vitro microenvironment.
基金funding from the European Research Council(ERC)under the European Union’s Horizon 2020 research and innovation program(Project MEMS4.0,ERC-2016-ADG,grant agreement No.742685)the EU’s H2020 framework program for research and innovation under grant agreement n.101007417,NFFA-Europe Pilot Project.M.B.acknowledges the support of SNSF Eccellenza grant No.PCEGP2_194528+4 种基金support from the QuantERA II Programme that has received funding from the European Union’s Horizon 2020 research and innovation program under Grant Agreement No 101017733G.F.and M.P.received funding through the European research council H2020-UE Framework Programme for Research&Innovation(2014-2020)ERC-2017-CoGInCellProject number 773091,and the Swiss National Science Foundation through grant 200021_182562.
文摘Grayscale structured surfaces with nanometer-scale features are used in a growing number of applications in optics and fluidics.Thermal scanning probe lithography achieves a lateral resolution below 10 nm and a vertical resolution below 1 nm,but its maximum depth in polymers is limited.Here,we present an innovative combination of nanowriting in thermal resist and plasma dry etching with substrate cooling,which achieves up to 10-fold amplification of polymer nanopatterns into SiO_(2) without proportionally increasing surface roughness.Sinusoidal nanopatterns in SiO_(2) with 400 nm pitch and 150 nm depth are fabricated free of shape distortion after dry etching.To exemplify the possible applications of the proposed method,grayscale dielectric nanostructures are used for scalable manufacturing through nanoimprint lithography and for strain nanoengineering of 2D materials.Such a method for aspect ratio amplification and smooth grayscale nanopatterning has the potential to find application in the fabrication of photonic and nanoelectronic devices.
文摘In the past decade, micro-electromechanical systems （MEMS）-based thermoelectric infrared （IR） sensors have received considerable attention because of the advances in micromachining technology. This paper presents a review of MEMS-based thermoelectric IR sensors. The first part describes the physics of the device and discusses the figures of merit. The second part discusses the sensing materials, thermal isolation micro- structures, absorber designs, and packaging methods for these sensors and provides examples. Moreover, the status of sensor implementation technology is examined from a historical perspective by presenting findings from the early years to the most recent findings.
基金This work was partially funded by projects 200020-105119/1 and 200021_143501/1 of the Swiss National Science Foundation.
文摘A moireis an interference pattern that appears when two different periodic structures are overlaid.The image created is extremely sensitive to small variations in the original layers and is thus very interesting for anti-counterfeit protection.We present a microfabricated 1D moire enabling complex high-resolution patterns as a significantly improved security feature that cannot be reproduced using standard printing methods.Furthermore,we demonstrate,theoretically and experimentally,that a microscopic deviation from the original design results in a macroscopic variation in the moire that is clearly visible to the naked eye.The record resolution achieved in the elements fabricated and the increased design freedom,make these high-resolution moires excellent candidates for a variety of visually appealing security applications.
基金This review paper is part of a project that has received funding from the European Research Council(ERC)under the European Union’s Horizon 2020 research and innovation program(Project“MEMS 4.0”,ERC-2016-ADG,grant agreement No.742685).
文摘Fundamental aspects and state-of-the-art results of thermal scanning probe lithography(t-SPL)are reviewed here.t-SPL is an emerging direct-write nanolithography method with many unique properties which enable original or improved nano-patterning in application fields ranging from quantum technologies to material science.In particular,ultrafast and highly localized thermal processing of surfaces can be achieved through the sharp heated tip in t-SPL to generate high-resolution patterns.We investigate t-SPL as a means of generating three types of material interaction:removal,conversion,and addition.Each of these categories is illustrated with process parameters and application examples,as well as their respective opportunities and challenges.Our intention is to provide a knowledge base of t-SPL capabilities and current limitations and to guide nanoengineers to the best-fitting approach of t-SPL for their challenges in nanofabrication or material science.Many potential applications of nanoscale modifications with thermal probes still wait to be explored,in particular when one can utilize the inherently ultrahigh heating and cooling rates.
基金This work is financially supported by the National Natural Science Foundation of China(Nos.61804023,61971108)the Key R&D Program of Sichuan Province(No.2018GZ0527)+1 种基金the Sichuan Science and Technology Program(Nos.2019YJ0198,2020YJ0015)the Fundamental Research Funds for the Central Universities(No.ZYGX2019Z002).
文摘With the rapid development of the Internet of Things(loT)and the emergence of 5G,traditional silicon-based electronics no Ion ger fully meet market dema nds such as nonplanar application scenarios due to mechanical mismatch.This provides unprecedented opportunities for flexible electronics that bypass the physical rigidity through the introduction of flexible materials.In recent decades,biological materials with outstanding biocompatibility and biodegradability,which are considered some of the most promising candidates for next-generation flexible electronics,have received increasing attention,e.g.,silk fibroin,cellulose,pectin,chitosan,and melanin.Among them,silk fibroin presents greater superiorities in biocompatibility and biodegradability,and moreover,it also possesses a variety of attractive properties,such as adjustable water solubility,remarkable optical transmittance,high mechanical robustness,light weight,and ease of processing,which are partially or even completely lacking in other biological materials.Therefore,silk fibroin has been widely used as fundamental components for the construction of biocompatible flexible electronics,particularly for wearable and implantable devices.Furthermore,in recent years,more attention has been paid to the investigation of the functional characteristics of silk fibroin;such as the dielectric properties,piezoelectric properties,strong ability to lose electrons,and sensitivity to environmental variables.Here,this paper not only reviews the preparation technologies for various forms of silk fibroin and the recent progress in the use of silk fibroin as a fundamental material but also focuses on the recent advaneed works in which silk fibroin serves as functional components.Additi on ally,the challenges and future development of silk fibroin-based flexible electronics are summarized.
基金This work was supported by the National Key Research and Development Program of China under Grants 2019YFB2005702 and 2018YFB2003001。
文摘The heat conduction and infrared absorption properties of the dielectric film have a great influence on the thermopile performance.Thinning the dielectric film,reducing its contact area with the silicon substrate,or adding high-absorptivity nano materials has been proven to be effective in improving thermopiles.However,these methods may result in a decrease in the structural mechanical strength and in creases in the fabrication complexity and cost.In this work,a new performa nce-enha ncement strategy for thermopiles by simultaneously con trolling the heat conduction and infrared absorption with a TExtured Dielectric(TEDI)film is developed and presented.The TEDI film is formed in situ by a simple hard-molding process that is compatible with the fabrication of traditional thermopiles.Compared to the control FLat Dielectric(FLDI)film,the intrinsic thermal conductance of the TEDI film can be reduced by〜18-30%,while the in fra red absorptio n can be increased by-7-13%.Corresp on dingly,the responsivity and detectivity of the fabricated TEDI film-based thermopile can be significantly enhanced by〜38-64%.An optimized TEDI film-based thermopile has achieved a responsivity of 156.89 V-W_1 and a detectivity of 2.16×10^(8)cm-Hz^(1/2)·W^(-1),while the response time constant can remain<12 ms.These results exhibit the great potential of using this strategy to develop high-performance thermopiles and enhance other sensors with heat transfer and/or infrared absorption mechanisms.
