The future intelligent era that will be brought about by 5G technology can be well predicted.For example,the connection between humans and smart wearable devices will become increasingly more intimate.Flexible wearabl...The future intelligent era that will be brought about by 5G technology can be well predicted.For example,the connection between humans and smart wearable devices will become increasingly more intimate.Flexible wearable pressure sensors have received much attention as a part of this process.Nevertheless,there is a lack of complete and detailed discussion on the recent research status of capacitive pressure sensors composed of polymer composites.Therefore,this article will mainly discuss the key concepts,preparation methods and main performance of flexible wearable capacitive sensors.The concept of a processing“toolbox”is used to review the developmental status of the dielectric layer as revealed in highly cited literature from the past five years.The preparation methods are categorized into types of processing:primary and secondary.Using these categories,the preparation methods and structure of the dielectric layer are discussed.Their influence on the final capacitive sensing behavior is also addressed.Recent developments in the electrode layer are also systematically reviewed.Finally,the results of the above discussion are summarized and future development trends are discussed.展开更多
In recent decades,capacitive pressure sensors(CPSs)with high sensitivity have demonstrated significant potential in applications such as medical monitoring,artificial intelligence,and soft robotics.Efforts to enhance ...In recent decades,capacitive pressure sensors(CPSs)with high sensitivity have demonstrated significant potential in applications such as medical monitoring,artificial intelligence,and soft robotics.Efforts to enhance this sensitivity have predominantly focused on material design and structural optimization,with surface microstructures such as wrinkles,pyramids,and micro-pillars proving effective.Although finite element modeling(FEM)has guided enhancements in CPS sensitivity across various surface designs,a theoretical understanding of sensitivity improvements remains underexplored.This paper employs sinusoidal wavy surfaces as a representative model to analytically elucidate the underlying mechanisms of sensitivity enhancement through contact mechanics.These theoretical insights are corroborated by FEM and experimental validations.Our findings underscore that optimizing material properties,such as Young’s modulus and relative permittivity,alongside adjustments in surface roughness and substrate thickness,can significantly elevate the sensitivity.The optimal performance is achieved when the amplitude-to-wavelength ratio(H/)is about 0.2.These results offer critical insights for designing ultrasensitive CPS devices,paving the way for advancements in sensor technology.展开更多
Bio-inspired near-sensor computing,which integrates sensing and processing functions,presents a promising strategy to enhance efficiency and reduce latency in such applications.Here,we introduce tactile sensory nerve ...Bio-inspired near-sensor computing,which integrates sensing and processing functions,presents a promising strategy to enhance efficiency and reduce latency in such applications.Here,we introduce tactile sensory nerve systems with biologically realistic energy efficiency,utilizing starfish-inspired capacitive pressure sensors integrated with flexible memristors.These starfish-inspired sensors,with their high aspect ratio(~3)and stress-focusing,hourglass-shaped dielectric microstructures,enable highly sensitive tactile detection across a broad pressure range,effectively mimicking the properties of human skin.Artificial tactile sensory nerves,which integrate the capacitive sensor with a flexible memristor exhibiting synaptic plasticity,function reliably as energy-efficient near-sensor computing systems by bio-realistically transducing mechanical stimuli into transient electrical signals.The developed system operates as both an artificial nociceptor and a tactile near-sensor computing unit,with energy consumption approaching biological levels at approximately 140 pJ and 2.2 fJ,respectively.This neuro-inspired localized computing strategy offers a physical platform for advanced smart user interface applications.展开更多
Electronic skin(e-skin) and flexible wearable devices are currently being developed with broad application prospects. Transforming electronic skin(e-skin) into true ¨skin¨is the ultimate goal. Tactile sensin...Electronic skin(e-skin) and flexible wearable devices are currently being developed with broad application prospects. Transforming electronic skin(e-skin) into true ¨skin¨is the ultimate goal. Tactile sensing is a fundamental function of skin and the development of high-performance flexible pressure sensors is necessary to realize thus. Many reports on flexible pressure sensors have been published in recent years,including numerous studies on improving sensor performance, and in particular, sensitivity. In addition,a number of studies have investigated self-healing materials, multifunctional sensing, and so on. Here,we review recent developments in flexible pressure sensors. First, working principles of flexible pressure sensors, including piezoresistivity, capacitance, and piezoelectricity, are introduced, as well as working mechanisms such as triboelectricity. Then studies on improving the performance of piezoresistive and capacitive flexible pressure sensors are discussed, in addition to other important aspects of this intriguing research field. Finally, we summarize future challenges in developing novel flexible pressure sensors.展开更多
Calcium copper titanate(CCTO)/polystyrenepolyethylene-polybutylene-poly styrene(SEBS)dielectric elastomers were prepared via blending method.A capacitive strain sensor using CCTO/SEBS as dielectric layer and polyanili...Calcium copper titanate(CCTO)/polystyrenepolyethylene-polybutylene-poly styrene(SEBS)dielectric elastomers were prepared via blending method.A capacitive strain sensor using CCTO/SEBS as dielectric layer and polyaniline-dodecylbenzensulfonic acid(PANI-DB S A)/SEBS as electrodes was designed and manufactured by thermoforming process.X-ray diffractometer(XRD),scanning electron microscopy(SEM)and Raman spectra analyses were carried out;no impurities were found in the composite and CCTO particles were well dispersed.The dielectric tests showed that the samples filled with 20 wt%CCTO have their permittivity improved by 70%.The capacitive strain sensors have a stabilized capacitance variety range at different strain ranges or stretch speeds,and could remain synchronized after 500-time-stretching,showing high reproducibility.展开更多
The development of intelligent electronic power systems necessitates advanced flexible pressure sensors.Despite improved compressibility through surface micro-structures or bulk pores,conventional capacitive pressure ...The development of intelligent electronic power systems necessitates advanced flexible pressure sensors.Despite improved compressibility through surface micro-structures or bulk pores,conventional capacitive pressure sensors face limitations due to their low dielectric constant and poor temperature tolerance of most elastomers.Herein,we constructed oriented polyimide-based aerogels with mechanical robustness and notable changes in dielectric constant under compression.The enhancement is attributed to the doping of surface-modified dielectric nanoparticles and graphene oxide sheets,which interact with polymer molecular chains.The resulting aerogels,with their excellent temperature resistance,were used to assemble high-performance capacitive pressure sensors.The sensor exhibits a maximum sensitivity of 1.41 kPa^(−1)over a wide working range of 0-200 kPa.Meanwhile,the sensor can operate in environments up to 150℃during 2000 compression/release cycles.Furthermore,the aerogel-based sensor demonstrates proximity sensing capabilities,showing great potential for applications in non-contact sensing and extreme environment detection.展开更多
In this paper, first a circular diaphragm is modeled using the classical plate theory. An analytical solution based on differential transformation method （DTM） and Runge-Kutta method is employed for solving the gove...In this paper, first a circular diaphragm is modeled using the classical plate theory. An analytical solution based on differential transformation method （DTM） and Runge-Kutta method is employed for solving the governing differential equation for the first time. Then the influences of various parameters on central deflection of the diaphragm, stress distribution and capacitance of pressure sensor with a time-dependent pressure are examined. Several case studies are compared with simulations to confirm the proposed method. The analytical results compared with ABAQUS simulation show excellent agreement with the simulation results. This method is very promising for time saving in calculating micro-device characteristics.展开更多
Soil properties and water content vary from place to place. The calibration method based on capacitive soil moisture and humidity sensor is carried out. The sensor readings are compared with the mass water content mea...Soil properties and water content vary from place to place. The calibration method based on capacitive soil moisture and humidity sensor is carried out. The sensor readings are compared with the mass water content measured by the oven dried method,and the calibration formula of sensor reading and mass moisture content is established.Results show that the sensor reading has a good linear relationship with the mass water content measured by the oven dried method,and has high precision. It can calibrate the mass moisture content of the data obtained from the moisture migration test in the soil column.展开更多
In this research paper,we have presented variable area type capacitive sensor signal conditioning system for angular displacement measurement and for this purpose we have used timer LM555 based astable multivibrator a...In this research paper,we have presented variable area type capacitive sensor signal conditioning system for angular displacement measurement and for this purpose we have used timer LM555 based astable multivibrator and universal frequency to digital converter (UFDC). Due to variation in angular displacement in the variable area type capacitor which is connected in the timer based astable circuit,capacitance changes which in turn changes the time period of the timer circuit output. The time period of the timer output waveform is linear with the capacitance and hence linear with angular displacement. The timer output is further processed with UFDC for the measurement. The experimental results show that the time period is linear with the angular displacement in the range of 0- 180° and the uncertainty we should associate it with this average time period value is the standard deviation of the mean,often called the standard error (SE),which is ± 0.023 μs. Because of the simplicity,this measurement system can be used in both electronic and industrial instrumentation.展开更多
A uniplanar capacitive sensor with 5-electrodes on one plane substrate and a large reflector electrode,was designed to get the corresponding capacitance information for weathering damage detection of non-metallic mate...A uniplanar capacitive sensor with 5-electrodes on one plane substrate and a large reflector electrode,was designed to get the corresponding capacitance information for weathering damage detection of non-metallic materials exposed to a service environment.A 2-D finite-element method was employed to simulate the electric potential distribution and capacitance measurements for the sensor.2 marble slabs,one was healthy and the other was notched,were experimentally detected.Both the simulation and the preliminary experimental results show that the measured capacitances decrease after weathering damage occurs in nonmetallic material.The reflector can enlarge the sensitive depth.The weathering assessment of nonmetallic materials can be done by processing the measured capacitances.The proposed approach can effectively detect the weathering damage of nonmetallic material and can be practically used for in-situ weathering damage evaluation.展开更多
Flexible pressure sensors have many potential applications in the monitoring of physiological signals because of their good biocompatibil-ity and wearability.However,their relatively low sensitivity,linearity,and stab...Flexible pressure sensors have many potential applications in the monitoring of physiological signals because of their good biocompatibil-ity and wearability.However,their relatively low sensitivity,linearity,and stability have hindered their large-scale commercial application.Herein,aflexible capacitive pressure sensor based on an interdigital electrode structure with two porous microneedle arrays(MNAs)is pro-posed.The porous substrate that constitutes the MNA is a mixed product of polydimethylsiloxane and NaHCO3.Due to its porous and interdigital structure,the maximum sensitivity(0.07 kPa-1)of a porous MNA-based pressure sensor was found to be seven times higher than that of an imporous MNA pressure sensor,and it was much greater than that of aflat pressure sensor without a porous MNA structure.Finite-element analysis showed that the interdigital MNA structure can greatly increase the strain and improve the sensitivity of the sen-sor.In addition,the porous MNA-based pressure sensor was found to have good stability over 1500 loading cycles as a result of its bilayer parylene-enhanced conductive electrode structure.Most importantly,it was found that the sensor could accurately monitor the motion of afinger,wrist joint,arm,face,abdomen,eye,and Adam’s apple.Furthermore,preliminary semantic recognition was achieved by monitoring the movement of the Adam’s apple.Finally,multiple pressure sensors were integrated into a 33 array to detect a spatial pressure distribu-×tion.Compared to the sensors reported in previous works,the interdigital electrode structure presented in this work improves sensitivity and stability by modifying the electrode layer rather than the dielectric layer.展开更多
Recently,electronic skins and fl exible wearable devices have been developed for widespread applications in medical monitoring,artifi cial intelligence,human–machine interaction,and artifi cial prosthetics.Flexible p...Recently,electronic skins and fl exible wearable devices have been developed for widespread applications in medical monitoring,artifi cial intelligence,human–machine interaction,and artifi cial prosthetics.Flexible proximity sensors can accurately perceive external objects without contact,introducing a new way to achieve an ultrasensitive perception of objects.This article reviews the progress of fl exible capacitive proximity sensors,fl exible triboelectric proximity sensors,and fl exible gate-enhanced proximity sensors,focusing on their applications in the electronic skin fi eld.Herein,their working mechanism,materials,preparation methods,and research progress are discussed in detail.Finally,we summarize the future challenges in developing fl exible proximity sensors.展开更多
In this paper, a micro capacitive sensor with nanometer resolution is presented for ultra-precision measurement of micro components, which is fabricated by the MEMS （micro electromechanical systems） non-silicon tech...In this paper, a micro capacitive sensor with nanometer resolution is presented for ultra-precision measurement of micro components, which is fabricated by the MEMS （micro electromechanical systems） non-silicon technique. Based on the sensor, a micro capacitive tactile probe is constructed by stylus assembly and packaging design for dimension metrology on micro/nano scale, in which a data acquiring system is developed with AD7747. Some measurements of the micro capacitive tactile probe are performed on a nano positioning and measuring machine （NMM）. The measurement results show good linearity and hysteresis with a range of 11.6 μm and resolution of better than 5 nm. Hence, the micro capacitive tactile probe can be integrated on NMM to realize measurement of micro structures with nanometer accuracy.展开更多
Sensing structure of grid strip capacitors can be used in the design of capacitive micro-electromechanical system （MEMS） resonators, accelerometers etc. A grid strip structure consists of nonentirely overlap plates ...Sensing structure of grid strip capacitors can be used in the design of capacitive micro-electromechanical system （MEMS） resonators, accelerometers etc. A grid strip structure consists of nonentirely overlap plates so that the capacitor fringe effect cannot be neglected in the design. Electricmagnetic Finite Element Method （FEM） software ANSOFF-Maxwell is employed to analyze the fringe effect of a grid strip capacitor. The analysis includes capacitance changes with change of overlap length, overlap width, plate thickness, grid strip density etc. The results show that fringe effect leads to non-linear change of grid strip capacitance with the change of overlap length and width, that the capacitance increases with the increase of grid strip width and plate thickness, and that sensitivity can be improved through the increase of grid strip density in the condition of identical total overlap area, but linearity is reduced.展开更多
Flexible pressure monitoring device can help correct the sitting posture and prevent health problems(e.g.,deformity of spinal column and musculoskeletal disease).Currently,most measurement systems hinder their wide ap...Flexible pressure monitoring device can help correct the sitting posture and prevent health problems(e.g.,deformity of spinal column and musculoskeletal disease).Currently,most measurement systems hinder their wide applications owing to the high cost or low accuracy.In this study,a flexible sitting pressure measurement system was proposed based on a textile-based capacitive pressure sensor array in order to measure sitting pressure distribution simply and conveniently.The capacitive pressure sensor array is sandwich structure composed of a high-density sponge layer and two electrode array fabrics,which possesses high resolution(2.26 sensors/cm^(2)),high sensitivity(0.701 kPa^(-1))and fast response(≤35 ms).It is worth noting that the raw materials of the sensing fabric include commercialized copper sheets and polyester yarns.The as-prepared pressure measurement system can accurately measure the pressure distribution nephogram for sitting posture analysis.The sitting pressure of 10 volunteers was measured and six types of posture were distinguished clearly.展开更多
This review explores the current state and future prospects of tactile sensing technologies in space robotics,addressing the unique challenges posed by harsh space environments such as extreme temperatures,radiation,m...This review explores the current state and future prospects of tactile sensing technologies in space robotics,addressing the unique challenges posed by harsh space environments such as extreme temperatures,radiation,microgravity,and vacuum conditions,which necessitate specialized sensor designs.We provide a detailed analysis of four primary types of tactile sensors:resistive,capacitive,piezoelectric,and optical,evaluating their operating principles,advantages,limitations,and specific applications in space exploration.Recent advancements in materials science,including the development of radiation-hardened components and flexible sensor materials,are discussed alongside innovations in sensor design and integration techniques that enhance performance and durability under space conditions.Through case studies of various space robotic systems,such as Mars rovers,robotic arms like Canadarm,humanoid robots like Robonaut,and specialized robots like Astrobee and LEMUR 3,this review highlights the crucial role of tactile sensing in enabling precise manipulation,environmental interaction,and autonomous operations in space.Moreover,it synthesizes current research and applications to underscore the transformative impact of tactile sensing technologies on space robotics and highlights their pivotal role in expanding human presence and scientific understanding in space,offering strategic insights and recommendations to guide future research and development in this critical field.展开更多
This paper presents the characteristics of a double helix capacitance sensor for measurement of the liquid holdup in horizontal oil–water two-phase flow. The finite element method is used to calculate the sensitivity...This paper presents the characteristics of a double helix capacitance sensor for measurement of the liquid holdup in horizontal oil–water two-phase flow. The finite element method is used to calculate the sensitivity field of the sensor in a pipe with 20 mm inner diameter and the effect of sensor geometry on the distribution of sensitivity field is presented. Then, a horizontal oil–water two-phase flow experiment is carried out to measure the response of the double helix capacitance sensor, in which a novel method is proposed to calibrate the liquid holdup based on three pairs of parallel-wire capacitance probes. The performance of the sensor is analyzed in terms of the flow structures detected by mini-conductance array probes.展开更多
Liquid metal(LM)dielectric elastomers with high flexibility and excellent dielectric properties are ideal for flexible capacitive pressure sensors.However,the development of LM dielectric elastomers is hindered by the...Liquid metal(LM)dielectric elastomers with high flexibility and excellent dielectric properties are ideal for flexible capacitive pressure sensors.However,the development of LM dielectric elastomers is hindered by the challenge of unavoidable percolation at high LM fill ratios.Inhomogeneous distribution is an effective strategy to manipulate the percolation threshold.Herein,thermoplastic polyurethane(TPU)fiber mats featuring a unique rapeseed-shaped structure were designed for high LM content filling(up to 90 vol%)and prepared with the aid of an electrospinning technique,in which LM was locally concentrated in the TPU fibers of the composite mats to form isolated clusters,leading to an incredible improvement in the percolation threshold surpassing our calculated theoretical prediction(>90 vol%vs.83 vol%).The LM/TPU-Fiber mats are proven to be recyclable,temperature-insensitive,and waterproof,making them suitable for multiple usage environments.A flexible capacitive sensor prepared with LM/TPU-Fiber mats,capable of exceptional relative capacitance change(Max.ΔC/C_(0)=6.32),an impressive pressure range of 0-550 kPa with a sensitivity of 55 MPa^(−1),and high cyclic stability(>6000 cycles).With these outstanding attributes,the sensor holds great promise for applications in intelligent sorting,pressure distribution monitoring,and human-machine interaction.展开更多
The design of a maskless exposure system for fabricating the microstructured surface based on the grainy light illumination generated by laser speckle is reported. Upon combining with soft lithography, we obtained mic...The design of a maskless exposure system for fabricating the microstructured surface based on the grainy light illumination generated by laser speckle is reported. Upon combining with soft lithography, we obtained microstructured polydimethylsiloxane electrodes with microstructure sizes of 20 μm and 40 μm and microstructure fill factors ranging from 10% to 90%. The feasibility of using this method in fabricating high-sensitivity capacitive pressure sensors was demonstrated. The sensor shows the highest sensitivity of 2.14 k Pa-1under 0–100 Pa pressures, the low detection limit of 4.9 Pa, and the excellent stability and durability of 10000 cycles. The method of employing laser speckle in fabricating microstructures with different morphologies is simple and robust, which is superior to other methods such as traditional photolithography.展开更多
For our research, a new hybrid experimental-computational method is presented. We applied a least squares fitting method （LSFM） to reconstruct the wood moisture content （WMC） from the data measured with a planar c...For our research, a new hybrid experimental-computational method is presented. We applied a least squares fitting method （LSFM） to reconstruct the wood moisture content （WMC） from the data measured with a planar capacitance sensor. A boundary element method （BEM） was used to compute the relationship between capacitance and the dielectric constant. A functional relationship between MC and the dielectric constant was identified by LSFM. The agreement of this final computation result with the experimental data indicates that this method can be used to estimate the WMC quickly and effectively with engineering analysis. Compared with popular statistical methods, a large number of experiments are avoided, some costs of testing are reduced and the efficiency of testing is enhanced.展开更多
基金The authors gratefully acknowledge the financial support of this work by National Natural Science Foundation of China(51773139,51922071).
文摘The future intelligent era that will be brought about by 5G technology can be well predicted.For example,the connection between humans and smart wearable devices will become increasingly more intimate.Flexible wearable pressure sensors have received much attention as a part of this process.Nevertheless,there is a lack of complete and detailed discussion on the recent research status of capacitive pressure sensors composed of polymer composites.Therefore,this article will mainly discuss the key concepts,preparation methods and main performance of flexible wearable capacitive sensors.The concept of a processing“toolbox”is used to review the developmental status of the dielectric layer as revealed in highly cited literature from the past five years.The preparation methods are categorized into types of processing:primary and secondary.Using these categories,the preparation methods and structure of the dielectric layer are discussed.Their influence on the final capacitive sensing behavior is also addressed.Recent developments in the electrode layer are also systematically reviewed.Finally,the results of the above discussion are summarized and future development trends are discussed.
基金supported by the National Natural Science Foundation of China(Grant No.12272369)the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDB0620101).
文摘In recent decades,capacitive pressure sensors(CPSs)with high sensitivity have demonstrated significant potential in applications such as medical monitoring,artificial intelligence,and soft robotics.Efforts to enhance this sensitivity have predominantly focused on material design and structural optimization,with surface microstructures such as wrinkles,pyramids,and micro-pillars proving effective.Although finite element modeling(FEM)has guided enhancements in CPS sensitivity across various surface designs,a theoretical understanding of sensitivity improvements remains underexplored.This paper employs sinusoidal wavy surfaces as a representative model to analytically elucidate the underlying mechanisms of sensitivity enhancement through contact mechanics.These theoretical insights are corroborated by FEM and experimental validations.Our findings underscore that optimizing material properties,such as Young’s modulus and relative permittivity,alongside adjustments in surface roughness and substrate thickness,can significantly elevate the sensitivity.The optimal performance is achieved when the amplitude-to-wavelength ratio(H/)is about 0.2.These results offer critical insights for designing ultrasensitive CPS devices,paving the way for advancements in sensor technology.
基金supported by the National R&D Program through the National Research Foundation of Korea(NRF),funded by the Ministry of Science and ICT(No.RS-2023-00277635)supported by the National Research Foundation of Korea(NRF)grant funded by the Korea government(MSIT)(No.RS-2024-00411764)+1 种基金supported by a grant of the Basic Research Program funded by the Korea Institute of Machinery and Materials(grant number:NK254H)the Technology Innovation Program(RS-2024-00443121)funded By the Ministry of Trade Industry&Energy(MOTIE,Korea).
文摘Bio-inspired near-sensor computing,which integrates sensing and processing functions,presents a promising strategy to enhance efficiency and reduce latency in such applications.Here,we introduce tactile sensory nerve systems with biologically realistic energy efficiency,utilizing starfish-inspired capacitive pressure sensors integrated with flexible memristors.These starfish-inspired sensors,with their high aspect ratio(~3)and stress-focusing,hourglass-shaped dielectric microstructures,enable highly sensitive tactile detection across a broad pressure range,effectively mimicking the properties of human skin.Artificial tactile sensory nerves,which integrate the capacitive sensor with a flexible memristor exhibiting synaptic plasticity,function reliably as energy-efficient near-sensor computing systems by bio-realistically transducing mechanical stimuli into transient electrical signals.The developed system operates as both an artificial nociceptor and a tactile near-sensor computing unit,with energy consumption approaching biological levels at approximately 140 pJ and 2.2 fJ,respectively.This neuro-inspired localized computing strategy offers a physical platform for advanced smart user interface applications.
基金supported by the National Natural Science Foundation of China(Nos.61775032,61475134 and 11604042)the Fundamental Research Funds for the Central Universities(N170405007,N180406002,N180408018 and N160404009)the 111 Project(B16009)。
文摘Electronic skin(e-skin) and flexible wearable devices are currently being developed with broad application prospects. Transforming electronic skin(e-skin) into true ¨skin¨is the ultimate goal. Tactile sensing is a fundamental function of skin and the development of high-performance flexible pressure sensors is necessary to realize thus. Many reports on flexible pressure sensors have been published in recent years,including numerous studies on improving sensor performance, and in particular, sensitivity. In addition,a number of studies have investigated self-healing materials, multifunctional sensing, and so on. Here,we review recent developments in flexible pressure sensors. First, working principles of flexible pressure sensors, including piezoresistivity, capacitance, and piezoelectricity, are introduced, as well as working mechanisms such as triboelectricity. Then studies on improving the performance of piezoresistive and capacitive flexible pressure sensors are discussed, in addition to other important aspects of this intriguing research field. Finally, we summarize future challenges in developing novel flexible pressure sensors.
基金financially supported by the National Natural Science Foundation of China(No.51403181)。
文摘Calcium copper titanate(CCTO)/polystyrenepolyethylene-polybutylene-poly styrene(SEBS)dielectric elastomers were prepared via blending method.A capacitive strain sensor using CCTO/SEBS as dielectric layer and polyaniline-dodecylbenzensulfonic acid(PANI-DB S A)/SEBS as electrodes was designed and manufactured by thermoforming process.X-ray diffractometer(XRD),scanning electron microscopy(SEM)and Raman spectra analyses were carried out;no impurities were found in the composite and CCTO particles were well dispersed.The dielectric tests showed that the samples filled with 20 wt%CCTO have their permittivity improved by 70%.The capacitive strain sensors have a stabilized capacitance variety range at different strain ranges or stretch speeds,and could remain synchronized after 500-time-stretching,showing high reproducibility.
基金financially supported by the National Key Research&Development Program of China(No.2022YFA1205200).
文摘The development of intelligent electronic power systems necessitates advanced flexible pressure sensors.Despite improved compressibility through surface micro-structures or bulk pores,conventional capacitive pressure sensors face limitations due to their low dielectric constant and poor temperature tolerance of most elastomers.Herein,we constructed oriented polyimide-based aerogels with mechanical robustness and notable changes in dielectric constant under compression.The enhancement is attributed to the doping of surface-modified dielectric nanoparticles and graphene oxide sheets,which interact with polymer molecular chains.The resulting aerogels,with their excellent temperature resistance,were used to assemble high-performance capacitive pressure sensors.The sensor exhibits a maximum sensitivity of 1.41 kPa^(−1)over a wide working range of 0-200 kPa.Meanwhile,the sensor can operate in environments up to 150℃during 2000 compression/release cycles.Furthermore,the aerogel-based sensor demonstrates proximity sensing capabilities,showing great potential for applications in non-contact sensing and extreme environment detection.
文摘In this paper, first a circular diaphragm is modeled using the classical plate theory. An analytical solution based on differential transformation method （DTM） and Runge-Kutta method is employed for solving the governing differential equation for the first time. Then the influences of various parameters on central deflection of the diaphragm, stress distribution and capacitance of pressure sensor with a time-dependent pressure are examined. Several case studies are compared with simulations to confirm the proposed method. The analytical results compared with ABAQUS simulation show excellent agreement with the simulation results. This method is very promising for time saving in calculating micro-device characteristics.
文摘Soil properties and water content vary from place to place. The calibration method based on capacitive soil moisture and humidity sensor is carried out. The sensor readings are compared with the mass water content measured by the oven dried method,and the calibration formula of sensor reading and mass moisture content is established.Results show that the sensor reading has a good linear relationship with the mass water content measured by the oven dried method,and has high precision. It can calibrate the mass moisture content of the data obtained from the moisture migration test in the soil column.
文摘In this research paper,we have presented variable area type capacitive sensor signal conditioning system for angular displacement measurement and for this purpose we have used timer LM555 based astable multivibrator and universal frequency to digital converter (UFDC). Due to variation in angular displacement in the variable area type capacitor which is connected in the timer based astable circuit,capacitance changes which in turn changes the time period of the timer circuit output. The time period of the timer output waveform is linear with the capacitance and hence linear with angular displacement. The timer output is further processed with UFDC for the measurement. The experimental results show that the time period is linear with the angular displacement in the range of 0- 180° and the uncertainty we should associate it with this average time period value is the standard deviation of the mean,often called the standard error (SE),which is ± 0.023 μs. Because of the simplicity,this measurement system can be used in both electronic and industrial instrumentation.
基金supported by the National Natural Science Foundation of China(60575015)
文摘A uniplanar capacitive sensor with 5-electrodes on one plane substrate and a large reflector electrode,was designed to get the corresponding capacitance information for weathering damage detection of non-metallic materials exposed to a service environment.A 2-D finite-element method was employed to simulate the electric potential distribution and capacitance measurements for the sensor.2 marble slabs,one was healthy and the other was notched,were experimentally detected.Both the simulation and the preliminary experimental results show that the measured capacitances decrease after weathering damage occurs in nonmetallic material.The reflector can enlarge the sensitive depth.The weathering assessment of nonmetallic materials can be done by processing the measured capacitances.The proposed approach can effectively detect the weathering damage of nonmetallic material and can be practically used for in-situ weathering damage evaluation.
基金supported in part by the National Natural Science Foundation of China(Grant No.62104056)the Zhejiang Provincial Natural Science Foundation of China(Grant No.LQ21F010010)+4 种基金the National Natural Science Foundation of China(Grant Nos.62141409 and 62204204)the National Key R&D Program of China(Grant No.2022ZD0208602)the Zhejiang Provincial Key Research&Development Fund(Grant Nos.2019C04003 and 2021C01041)the Shanghai Sailing Program(Grant No.21YF1451000)the Key Research and Development Program of Shaanxi(Grant No.2022GY-001).
文摘Flexible pressure sensors have many potential applications in the monitoring of physiological signals because of their good biocompatibil-ity and wearability.However,their relatively low sensitivity,linearity,and stability have hindered their large-scale commercial application.Herein,aflexible capacitive pressure sensor based on an interdigital electrode structure with two porous microneedle arrays(MNAs)is pro-posed.The porous substrate that constitutes the MNA is a mixed product of polydimethylsiloxane and NaHCO3.Due to its porous and interdigital structure,the maximum sensitivity(0.07 kPa-1)of a porous MNA-based pressure sensor was found to be seven times higher than that of an imporous MNA pressure sensor,and it was much greater than that of aflat pressure sensor without a porous MNA structure.Finite-element analysis showed that the interdigital MNA structure can greatly increase the strain and improve the sensitivity of the sen-sor.In addition,the porous MNA-based pressure sensor was found to have good stability over 1500 loading cycles as a result of its bilayer parylene-enhanced conductive electrode structure.Most importantly,it was found that the sensor could accurately monitor the motion of afinger,wrist joint,arm,face,abdomen,eye,and Adam’s apple.Furthermore,preliminary semantic recognition was achieved by monitoring the movement of the Adam’s apple.Finally,multiple pressure sensors were integrated into a 33 array to detect a spatial pressure distribu-×tion.Compared to the sensors reported in previous works,the interdigital electrode structure presented in this work improves sensitivity and stability by modifying the electrode layer rather than the dielectric layer.
基金supported by the National Key R&D Program of China(Nos.2022 YFF 1202700 and 2022YFB3203500)National Natural Science Foundation of China(Nos.62225403,62375046,51973024,an d U19A2091)+2 种基金“111”Project(No.B13013)Natur al Sci ence Foundation of Jilin Pro vin ce(No.20230101113JC)the Funding from Jilin Pr ovince(No.20220502002GH).
文摘Recently,electronic skins and fl exible wearable devices have been developed for widespread applications in medical monitoring,artifi cial intelligence,human–machine interaction,and artifi cial prosthetics.Flexible proximity sensors can accurately perceive external objects without contact,introducing a new way to achieve an ultrasensitive perception of objects.This article reviews the progress of fl exible capacitive proximity sensors,fl exible triboelectric proximity sensors,and fl exible gate-enhanced proximity sensors,focusing on their applications in the electronic skin fi eld.Herein,their working mechanism,materials,preparation methods,and research progress are discussed in detail.Finally,we summarize the future challenges in developing fl exible proximity sensors.
基金supported by the Nano Special Projects of Shanghai Science and Technology Commission of China(Grant No.11nm0560800)the Young Scientists Fund of the National Natural Science Foundation of China(Grant No.11104284)
文摘In this paper, a micro capacitive sensor with nanometer resolution is presented for ultra-precision measurement of micro components, which is fabricated by the MEMS （micro electromechanical systems） non-silicon technique. Based on the sensor, a micro capacitive tactile probe is constructed by stylus assembly and packaging design for dimension metrology on micro/nano scale, in which a data acquiring system is developed with AD7747. Some measurements of the micro capacitive tactile probe are performed on a nano positioning and measuring machine （NMM）. The measurement results show good linearity and hysteresis with a range of 11.6 μm and resolution of better than 5 nm. Hence, the micro capacitive tactile probe can be integrated on NMM to realize measurement of micro structures with nanometer accuracy.
基金Supported by the National Natural Science Foundation of China （ No. 60903195 ） and the Key Technological Problems Tackling Project of Wuhan （No. 200750499172）.
文摘Sensing structure of grid strip capacitors can be used in the design of capacitive micro-electromechanical system （MEMS） resonators, accelerometers etc. A grid strip structure consists of nonentirely overlap plates so that the capacitor fringe effect cannot be neglected in the design. Electricmagnetic Finite Element Method （FEM） software ANSOFF-Maxwell is employed to analyze the fringe effect of a grid strip capacitor. The analysis includes capacitance changes with change of overlap length, overlap width, plate thickness, grid strip density etc. The results show that fringe effect leads to non-linear change of grid strip capacitance with the change of overlap length and width, that the capacitance increases with the increase of grid strip width and plate thickness, and that sensitivity can be improved through the increase of grid strip density in the condition of identical total overlap area, but linearity is reduced.
基金Fundamental Research Fund for the Central Universities,China(Nos.2232020G-01 and 19D110106)Young Elite Scientists Sponsorship Program by China Association for Science and Technology,China(No.2017QNRC001)Graduate Student Innovation Fund of Donghua University,China(No.20D310111)。
文摘Flexible pressure monitoring device can help correct the sitting posture and prevent health problems(e.g.,deformity of spinal column and musculoskeletal disease).Currently,most measurement systems hinder their wide applications owing to the high cost or low accuracy.In this study,a flexible sitting pressure measurement system was proposed based on a textile-based capacitive pressure sensor array in order to measure sitting pressure distribution simply and conveniently.The capacitive pressure sensor array is sandwich structure composed of a high-density sponge layer and two electrode array fabrics,which possesses high resolution(2.26 sensors/cm^(2)),high sensitivity(0.701 kPa^(-1))and fast response(≤35 ms).It is worth noting that the raw materials of the sensing fabric include commercialized copper sheets and polyester yarns.The as-prepared pressure measurement system can accurately measure the pressure distribution nephogram for sitting posture analysis.The sitting pressure of 10 volunteers was measured and six types of posture were distinguished clearly.
基金supported by FAST(19FAYORA14)of the Canadian Space Agency,Discovery Grant(RGPIN2024-06290)supported by CREATE grant(555425-2021)&Discovery grant(RGPIN-2024-06290)of the Natural Sciences and Engineering Research Council of Canada.
文摘This review explores the current state and future prospects of tactile sensing technologies in space robotics,addressing the unique challenges posed by harsh space environments such as extreme temperatures,radiation,microgravity,and vacuum conditions,which necessitate specialized sensor designs.We provide a detailed analysis of four primary types of tactile sensors:resistive,capacitive,piezoelectric,and optical,evaluating their operating principles,advantages,limitations,and specific applications in space exploration.Recent advancements in materials science,including the development of radiation-hardened components and flexible sensor materials,are discussed alongside innovations in sensor design and integration techniques that enhance performance and durability under space conditions.Through case studies of various space robotic systems,such as Mars rovers,robotic arms like Canadarm,humanoid robots like Robonaut,and specialized robots like Astrobee and LEMUR 3,this review highlights the crucial role of tactile sensing in enabling precise manipulation,environmental interaction,and autonomous operations in space.Moreover,it synthesizes current research and applications to underscore the transformative impact of tactile sensing technologies on space robotics and highlights their pivotal role in expanding human presence and scientific understanding in space,offering strategic insights and recommendations to guide future research and development in this critical field.
基金Supported by the National Natural Science Foundation of China(50974095,41174109,61104148)the National Science and Technology Major Projects(2011ZX05020-006)
文摘This paper presents the characteristics of a double helix capacitance sensor for measurement of the liquid holdup in horizontal oil–water two-phase flow. The finite element method is used to calculate the sensitivity field of the sensor in a pipe with 20 mm inner diameter and the effect of sensor geometry on the distribution of sensitivity field is presented. Then, a horizontal oil–water two-phase flow experiment is carried out to measure the response of the double helix capacitance sensor, in which a novel method is proposed to calibrate the liquid holdup based on three pairs of parallel-wire capacitance probes. The performance of the sensor is analyzed in terms of the flow structures detected by mini-conductance array probes.
基金supported by NSFC No.52473267 and No.52401249National Key Research and Development Program of China No.2021YFB3501504 and Zhejiang Provincial Key Research and Development Program(2024C01157)Zhejiang University Ningbo“Five in One”Campus Project(K-20213539).
文摘Liquid metal(LM)dielectric elastomers with high flexibility and excellent dielectric properties are ideal for flexible capacitive pressure sensors.However,the development of LM dielectric elastomers is hindered by the challenge of unavoidable percolation at high LM fill ratios.Inhomogeneous distribution is an effective strategy to manipulate the percolation threshold.Herein,thermoplastic polyurethane(TPU)fiber mats featuring a unique rapeseed-shaped structure were designed for high LM content filling(up to 90 vol%)and prepared with the aid of an electrospinning technique,in which LM was locally concentrated in the TPU fibers of the composite mats to form isolated clusters,leading to an incredible improvement in the percolation threshold surpassing our calculated theoretical prediction(>90 vol%vs.83 vol%).The LM/TPU-Fiber mats are proven to be recyclable,temperature-insensitive,and waterproof,making them suitable for multiple usage environments.A flexible capacitive sensor prepared with LM/TPU-Fiber mats,capable of exceptional relative capacitance change(Max.ΔC/C_(0)=6.32),an impressive pressure range of 0-550 kPa with a sensitivity of 55 MPa^(−1),and high cyclic stability(>6000 cycles).With these outstanding attributes,the sensor holds great promise for applications in intelligent sorting,pressure distribution monitoring,and human-machine interaction.
基金supported by the National Key Research and Development Program of China (Grant No. 2017YFA0304203)the Key Research and Development Program of Shanxi Province (Grant No. 202102030201002)+3 种基金the Changjiang Scholars and Innovative Research Team in University of Ministry of Education of China (Grant No. IRT_17R70)the State Key Program of National Natural Science of China (Grant No. 11434007)the111 Project (Grant No. D18001)the Fund for Shanxi “1331 Project”。
文摘The design of a maskless exposure system for fabricating the microstructured surface based on the grainy light illumination generated by laser speckle is reported. Upon combining with soft lithography, we obtained microstructured polydimethylsiloxane electrodes with microstructure sizes of 20 μm and 40 μm and microstructure fill factors ranging from 10% to 90%. The feasibility of using this method in fabricating high-sensitivity capacitive pressure sensors was demonstrated. The sensor shows the highest sensitivity of 2.14 k Pa-1under 0–100 Pa pressures, the low detection limit of 4.9 Pa, and the excellent stability and durability of 10000 cycles. The method of employing laser speckle in fabricating microstructures with different morphologies is simple and robust, which is superior to other methods such as traditional photolithography.
基金supported by the Central University Basic Research Professional Expenses Special Foundation of Harbin Engineering University (Grant No. HEUCFL10101109)
文摘For our research, a new hybrid experimental-computational method is presented. We applied a least squares fitting method （LSFM） to reconstruct the wood moisture content （WMC） from the data measured with a planar capacitance sensor. A boundary element method （BEM） was used to compute the relationship between capacitance and the dielectric constant. A functional relationship between MC and the dielectric constant was identified by LSFM. The agreement of this final computation result with the experimental data indicates that this method can be used to estimate the WMC quickly and effectively with engineering analysis. Compared with popular statistical methods, a large number of experiments are avoided, some costs of testing are reduced and the efficiency of testing is enhanced.
