Flexible pressure sensors show great promise for applications in such fields as electronic skin,healthcare,and intelligent robotics.Traditional capacitive pressure sensors,however,face the problem of low sensitivity,w...Flexible pressure sensors show great promise for applications in such fields as electronic skin,healthcare,and intelligent robotics.Traditional capacitive pressure sensors,however,face the problem of low sensitivity,which limits their wider application.In this paper,a flexible capacitive pressure sensor with microstructured ionization layer is fabricated by a sandwich-type process,with a low-cost and simple process of inverted molding with sandpapers being used to form a thermoplastic polyurethane elastomer ionic film with double-sided microstructure as the dielectric layer of the sensor,with silver nanowires as electrodes.The operating mechanism of this iontronic pressure sensor is analyzed using a graphical method,and the sensor is tested on a pressure platform.The test results show that the sensor has ultrahigh pressure sensitivities of 3.744 and 1.689 kPa^(−1) at low(0-20 kPa)and high(20-800 kPa)pressures,respectively,as well as a rapid response time(100 ms),and it exhibits good stability and repeatability.The sensor can be used for sensitive monitoring of activities such as finger bending,and for facial expression(smile,frown)recognition,as well as speech recognition.展开更多
The fexible strain sensor has found widespread application due to its excellent fexibility,extensibility,and adaptability to various scenarios.This type of sensors face challenges in direction identification owing to ...The fexible strain sensor has found widespread application due to its excellent fexibility,extensibility,and adaptability to various scenarios.This type of sensors face challenges in direction identification owing to strong coupling between the principal strain and transverse resistance.In this study,a silver nanowires(Ag-NWs)/polydimethylsiloxane(PDMS)strain sensor was developed,using a filtration method for preparing the AgNWs film which was then combined with PDMS to create a unidirectional,highly sensitive,fast-responsive,and linear fexible strain sensor.When the grid width is 0.25 mm,the AgNWs/PDMS strain sensor demonstrates an outstanding unidirectional sensitivity,with a strain response solely along the parallel direction of the grid lines(noise ratioα≈8%),and a fast reaction time of roughly 106.99 ms.In the end,this sensor's ability to detect curvature was also demonstrated through LEDs,demonstrating its potential applications in various fields,including automotive,medical,and wearable devices.展开更多
A rectangular finite element for laminated plate with bonded and/or embedded piezoelectric sensors and actuators is developed based on the variational principle and the first order shear deformation theory. The elemen...A rectangular finite element for laminated plate with bonded and/or embedded piezoelectric sensors and actuators is developed based on the variational principle and the first order shear deformation theory. The element has four-node, 20-degrees-of-freedom with one potential degree of freedom for each piezoelectric layer to represent the piezoelectric behavior. The higher order derivation of deflection is obtained by using the normal rotation expressions to take the effects of transverse shear deformation into considerations. The finite element can accurately simulate the deformation of both thin and moderately thick plates. A Fortran program is written and a number of benchmark tests are exercised to verify its effectiveness. Results are compared well with the existing data. The unbalanced composite with piezoelectric layers is then analyzed by using the model. Results show that the changes of the ratio between the thickness of positive angle layers and the negative angle layers have an effect on the deformation of the structure under the same electric loading.展开更多
Aim to detect the characteristic weak magnetic field signal against the strong noises background. Methods In combination with a low-pass-filter, the correlation output of magne-* tic sensors between the magnetic field...Aim to detect the characteristic weak magnetic field signal against the strong noises background. Methods In combination with a low-pass-filter, the correlation output of magne-* tic sensors between the magnetic field and reference current was utilized to provide a DC output voltage proportional to the applied magnetic induction, computer simulation was* done to investigate the correlation output of the Hall-effect sensors. Results Some analysis results concerning the noise property, harmonic supppression and the sensitivity were given. Conclsion The minimum detection signal of the equipment evolved from the mentioned cor-* relation theory can be 10-6 T. In addition to the DC output, such sensors can also measure the phase of the detected magnetic induction and has good harmonic suppression as well as* noise elimination.展开更多
We propose a novel high-performance digital optical sensor based on the Mach-Zehnder interferential effect and the dual-microring resonators with the waveguide-coupled feedback. The simulation results show that the se...We propose a novel high-performance digital optical sensor based on the Mach-Zehnder interferential effect and the dual-microring resonators with the waveguide-coupled feedback. The simulation results show that the sensitivity of the sensor can be orders of magnitude higher than that of aconventional sensor, and high quality factor is not critical in it. Moreover, by optimizing the length of the feedback waveguide to be equal to the perimeter of the ring, the measurement range of the proposed sensor is twice as much as that of the conventional sensor in the weak coupling case.展开更多
A multi-coating technique of reduced graphene oxide(RGO)was proposed to increase the sensitivity of paper-based pressure sensors.The maximum sensitivity of 17.6 kPa^-1 under the 1.4 kPa was achieved.The electrical sen...A multi-coating technique of reduced graphene oxide(RGO)was proposed to increase the sensitivity of paper-based pressure sensors.The maximum sensitivity of 17.6 kPa^-1 under the 1.4 kPa was achieved.The electrical sensing mechanism is attributed to the percolation effect.Such paper pressure sensors were applied to monitor the motor vibration,which indicates the potential of mechanical flaw detection by analyzing the waveform difference.展开更多
In vibration active control of composite structures, piezoelectricsensors/actuators are usually bonded to the surface of a host structure. Debonding of piezoelectricsensors/actuators can result in significant changes ...In vibration active control of composite structures, piezoelectricsensors/actuators are usually bonded to the surface of a host structure. Debonding of piezoelectricsensors/actuators can result in significant changes to the static and dynamic response. In thepresent paper, an novel Enhanced Assumed Strain(EAS) piezoelectric solid element formulation isdeveloped for vibration active control of laminated structures bonded with piezoelectric sensors andactuators. Unlike the conventional brick elements, the present formulation is very reliable, moreaccurate, and computationally efficient and can be used to model the response of shell structuresbesides thin plates. Delaminations are modeled by pairs of nodes with the same coordinates butdifferent node numbers, and numerical results demonstrate the performance of the element and theglobal and local effects of debonding sensors/actuators on the dynamics of the adaptive laminates.展开更多
Flexible hydrogels have shown promise as strain sensors in medical monitoring,human motion detection and intelligent robotics.For a hydrogel strain sensor,certain challenges need to be urgently addressed for practical...Flexible hydrogels have shown promise as strain sensors in medical monitoring,human motion detection and intelligent robotics.For a hydrogel strain sensor,certain challenges need to be urgently addressed for practical applications,such as the damage caused by external effects,leading to equipment failure,and the inability to perceive ambient temperature,resulting in single functionality.Herein,a stretchable,self-healing and dual temperature-strain sensitive hydrogel,with a physically-crosslinked network,is designed by constructing multiple dynamic reversible bonds.Graphene oxide(GO)and iron ions(Fe^(3+))act as dynamic bridges in the cross-linked network and are mediated by the covalent and hydrogen bonding,rendering excellent stretchability to the hydrogel.The reversible features of coordination interactions and hydrogen interactions endow excellent recoverability and self-healing properties.Moreover,the incorporated N-isopropyl acrylamide(NIPAM)provides excellent temperature responsiveness to the hydrogel,facilitating the detection of external temperature changes.Meanwhile,the hydrogels exhibited strain-sensitivity,with a wide working range of 1%-300%,fast response and electrical stability,which can be used as flexible sensors to monitor body motions,e.g.,speaking and the bending of finger,wrist,elbow and knee.Overall,the hydrogel possesses dual sensory capabilities,combining external temperature and strain,for potential applications in wearable multifunctional sensing devices.展开更多
Highly sensitive pressure sensors are often deployed in human-machine interaction area,touch screen and human motion detection.However,there are still great challenges to fabricating with high sensitivity pressure sen...Highly sensitive pressure sensors are often deployed in human-machine interaction area,touch screen and human motion detection.However,there are still great challenges to fabricating with high sensitivity pressure sensor with wide-range detection.Herein,we developed a new strategy to fabricate a highly sensitive pressure sensor using sandpaper and improve its detection range using a sacrificial template.It was the fthatirst time to combine microstructure processing with the sacrificial template method to fabricate pressure sensor.The microstructure of sandpaper endowed the sensor with high sensitivity,and the elastic substrate enhanced the sensor ability to resist high pressure without being damaged.The fabricated sensor device exhibits a superior sensitivity of 39.077 kPa-1in the range from 50 kPa to 110 kPa with a broad linear response.Remarkably,high pressure ceiling(<160 kPa) ensures that the sponge could be applied in different practical conditions to monitor a range of subtle human motions including finger,wrist bending,and pulse.For applications,the sensor device can not only detect the foot stepping behavior(0.7 MPa) but also produce an obvious response to an extremely slight paper(9 mg,~0.9 Pa).The successful preparation of this micro-structured elastic sponge material provided new ideas for exploring its potential applications in pressure sensors and flexible wearable electronic devices.展开更多
The flourishing development in flexible electronics has provoked intensive research in flexible strain sensors to realize accurate perception acquisition under different external stimuli.However,building hydrogel-base...The flourishing development in flexible electronics has provoked intensive research in flexible strain sensors to realize accurate perception acquisition under different external stimuli.However,building hydrogel-based strain sensors with high stretchability and sensitivity remains a great challenge.Herein,MXene nanosheets were composited into polyacrylamide-sodium alginate matrix to construct mechanical robust and sensitive double networked hydrogel strain sensor.The hydrophilic MXene nanosheets formed strong interactions with the polymer matrix and endowed the hydrogel with excellent tensile properties(3150%),compliant mechanical strength(2.03 kPa^(-1)in Young’s Module)and long-lasting stability and fatigue resistance(1000 dynamic cycles under 1,600%strain).Due to the highly oriented MXene-based three dimensional conductive networks,the hydrogel sensor achieved extremely high tensile sensitivity(18.15 in gauge factor)and compression sensitivity(0.38 kPa^(-1)below 3 kPa).MXene hydrogel-based strain sensors also displayed negligible hysteresis in electromechanical performance,typical frequent-independent feature and rapid response time to external stimuli.Moreover,the sensor exhibited accurate response to different scales of human movements,providing potential application in speech recognition,expression recognition and handwriting verification.展开更多
L-kynurenine(L-kyn)is a marker of prostate cancer.At present,the expensive instruments are usually applied to detect L-kyn clinically,which limits its wide application for cancer diagnosis.Herein,three lanthanide meta...L-kynurenine(L-kyn)is a marker of prostate cancer.At present,the expensive instruments are usually applied to detect L-kyn clinically,which limits its wide application for cancer diagnosis.Herein,three lanthanide metal-organic frameworks([Ln(CHO_(2))_(3)]_(n),Ln=Eu,Gd,and Tb)were designed and obtained,and detailly characterized by single crystal X-ray diffraction(SCXRD),powder X-ray diffraction(PXRD),Fourier transform infrared spectroscopy(FT-IR),thermogravimetric analysis(TGA),and luminescence spectroscopy.Further study reveals that[Tb(CHO_(2))_(3)]_(n)is a highly selective,ultra-sensitive,of strong anti-interference,highly stable,and non-expensive sensor for prostate cancer marker L-kyn.The limit of detection(LOD)for L-kyn sensing is a highly sensitive value of 1.0×10^(−9)mol/L.Furthermore,the sensing mechanism is discussed in detail.展开更多
Human–machine interactions using deep-learning methods are important in the research of virtual reality,augmented reality,and metaverse.Such research remains challenging as current interactive sensing interfaces for ...Human–machine interactions using deep-learning methods are important in the research of virtual reality,augmented reality,and metaverse.Such research remains challenging as current interactive sensing interfaces for single-point or multipoint touch input are trapped by massive crossover electrodes,signal crosstalk,propagation delay,and demanding configuration requirements.Here,an all-inone multipoint touch sensor(AIOM touch sensor)with only two electrodes is reported.The AIOM touch sensor is efficiently constructed by gradient resistance elements,which can highly adapt to diverse application-dependent configurations.Combined with deep learning method,the AIOM touch sensor can be utilized to recognize,learn,and memorize human–machine interactions.A biometric verification system is built based on the AIOM touch sensor,which achieves a high identification accuracy of over 98%and offers a promising hybrid cyber security against password leaking.Diversiform human–machine interactions,including freely playing piano music and programmatically controlling a drone,demonstrate the high stability,rapid response time,and excellent spatiotemporally dynamic resolution of the AIOM touch sensor,which will promote significant development of interactive sensing interfaces between fingertips and virtual objects.展开更多
The World Health Organization has declared COVID-19 a pandemic.The demand for devices or systems to diagnose and track COVID-19 infections noninvasively not only in hospitals but also in home settings has led to incre...The World Health Organization has declared COVID-19 a pandemic.The demand for devices or systems to diagnose and track COVID-19 infections noninvasively not only in hospitals but also in home settings has led to increased interest in consumer-grade wearables.A common symptom of COVID-19 is dyspnea,which may manifest as an increase in respiratory and heart rates.In this paper,a novel piezoelectric strain sensor is presented for real-time monitoring of respiratory and heartbeat signals.A highly sensitive and stretchable piezoelectric strain sensor is fabricated using a piezoelectric film with a serpentine layout.The thickness of the patterned PVDF flexible piezoelectric strain sensor is only 168μm,and the voltage sensitivity reaches 0.97 mV/με.The effective modulus is 13.5 MPa,which allows the device to fit to the skin and detect the small strain exhibited by the human body.Chest vibrations are captured by the piezoelectric sensor,which produces an electrical output voltage signal conformally mapped with respiratory–cardiac activities.The separate heart activity and respiratory signals are extracted from the mixed respiratory–cardiac signal by an empirical mode decomposition data processing algorithm.By detecting vital signals such as respiratory and heart rates,the proposed device can aid early diagnosis and monitoring of respiratory diseases such as COVID-19.展开更多
The aim of this work is to model and analyze the behavior of a new smart nano force sensor.To do so,the carbon nanotube has been used as a suspended gate of a metal-oxide-semiconductor field-effect transistor(MOSFET)....The aim of this work is to model and analyze the behavior of a new smart nano force sensor.To do so,the carbon nanotube has been used as a suspended gate of a metal-oxide-semiconductor field-effect transistor(MOSFET).The variation of the applied force on the carbon nanotube(CNT)generates a variation of the capacity of the transistor oxide-gate and therefore the variation of the threshold voltage,which allows the MOSFET to become a capacitive nano force sensor.The sensitivity of the nano force sensor can reach 0.12431V/nN.This sensitivity is greater than results in the literature.We have found through this study that the response of the sensor depends strongly on the geometric and physical parameters of the CNT.From the results obtained in this study,it can be seen that the increase in the applied force increases the value of the MOSFET threshold voltage VTh.In this paper,we first used artificial neural networks to faithfully reproduce the response of the nano force sensor model.This neural model is called direct model.Then,secondly,we designed an inverse model called an intelligent sensor which allows linearization of the response of our developed force sensor.展开更多
A novel fiber strain sensor is proposed, based on the two-mode interference of a suspended-core fiber. A fullvectorial finite difference mode solver is employed as the numerical tool for characterizing the proposed st...A novel fiber strain sensor is proposed, based on the two-mode interference of a suspended-core fiber. A fullvectorial finite difference mode solver is employed as the numerical tool for characterizing the proposed strain sensor. The numerical results show that the proposed strain sensor has an estimated sensitivity of 0.05 rad/（m-με）, higher than that of the strain sensors using conventional multimode fibers, while the temperature sensitivity of the proposed sensor is relatively low.展开更多
Chiral metamaterials have been a topic of significant research interest in recent years due to their potential for various applications in nanophotonic devices and chiral biosensors.However,the intrinsic Ohmic loss in...Chiral metamaterials have been a topic of significant research interest in recent years due to their potential for various applications in nanophotonic devices and chiral biosensors.However,the intrinsic Ohmic loss in surface plasmonic resonance has limited their practical use,resulting in large light dissipation and weak chiroptical resonance.Here,we report on the development of high-performance dielectric chiral shells(DCS)through a two-step Si deposition process on a self-assembled microsphere monolayer.The form DCS sample completely oyercomes the cancelation effect originated from the disorder property of the micro-sphere monolayer in macroscale,and at a wavelength of approximately 710 nm,the measured optimal chiral signal(g-factor)and transmittance can reach up to 0.7 and 0.3,respectively.The strong chiroptical effect comes from the asymmetric circular displacement currents(i.e.,magnetic modes)enabled by the specific shell geometry.The chiral shell geometry,electromagnetic properties,sensor sensitivity of chiral molecules and figure of merit are systematically investigated.The DCSs demonstrate highly sensitive detection of chiral biomolecules owing to their easily accessible geometry and enhanced uniform chiral field.展开更多
A polymeric membrane ion-selective electrode for determination of heparin is described in this paper.Protamine is incorporated into the organic membrane phase and functions as sensing element for selective recognition...A polymeric membrane ion-selective electrode for determination of heparin is described in this paper.Protamine is incorporated into the organic membrane phase and functions as sensing element for selective recognition of heparin.The proposed membrane electrode exhibits high selectivity for heparin over lipophilic anions such as thiocyanide and salicylate.The potentiometric response to the concentration of heparin is Unear in the range of 0.01-0.4 U/mL and a lower detection limit of 0.005 U/mL can be achieved.展开更多
We have demonstrated and analyzed the methane gas sensor based on octagonal cladding and hexagonal hybrid porous core photonic crystal fiber (HPC-PCF) for gas detection purpose. The proposed design of HPC-PCF has been...We have demonstrated and analyzed the methane gas sensor based on octagonal cladding and hexagonal hybrid porous core photonic crystal fiber (HPC-PCF) for gas detection purpose. The proposed design of HPC-PCF has been numerically investigated by COMSOL Multiphysics software through utilizing the full vectorial finite element method (FEM). The optical characteristics of HPC-PCF as well as confinement loss, relative sensitivity and refractive index, effective area, nonlinearity and numerical aperture are optimized properly by changing the geometrical parameters as well as air filling ratio, air hole diameter, pitch constant of cladding and porosity of the core. In this simulation work, we have achieved optimum relative sensitivity of 21.2%, and confinement loss of 0.000025 dB/m at 3 μm pitch, 0.7 air filling ratio of the cladding and 29% porosity of the core for 3.5 μm absorption wavelength of CH4 gas. This proposed design of HPC-PCF will keep exclusive contribution for detecting the CH4 gas accurately.展开更多
The highly-dispersed iron element decorated Ni foam was prepared by simple immersion in a ferric nitrate solution at room temperature without using acid etching, and characterized by X-ray powder diffraction(XRD), sca...The highly-dispersed iron element decorated Ni foam was prepared by simple immersion in a ferric nitrate solution at room temperature without using acid etching, and characterized by X-ray powder diffraction(XRD), scanning electron microscopy(SEM), EDAX spectrum(EDAX mapping) and Raman spectroscopy. The EDAX spectrum illustrated that iron element was highly-dispersed over the entire surface of nickel foam, and the Raman spectroscopy revealed that both Ni-O and Fe-O bonds were formed on the surface of the as-prepared electrode. Moreover, the iron element decorated Ni foam electrode can be used as non-enzymatic glucose sensor and it exhibits not only an ultra-wide linear concentration range of 1-18 mmol/L with an outstanding sensitivity of 1.0388 m A·mmol/(L·cm2), but also an excellent ability of stability and selectivity. Therefore, this work presents a simple yet effective approach to successfully modify Ni foam as non-enzymatic glucose sensor.展开更多
基金supported by the Youth Project of the National Natural Science Foundation of China(Grant No.52105594)the Youth Project of the Applied Basic Research Program of Shanxi Province(Grant No.20210302124274)+4 种基金the Key Research and Development Program of Shanxi Province(Grant No.202102030201005)the Natural Youth Science Foundation of Shanxi Province(Grant Nos.202103021223005 and 202203021212015)the Fund for Shanxi 1331 Project,the Science and Technology Innovation Plan for Colleges and Universities in Shanxi Province(Grant No.2022L575)the Science and Technology Innovation Project in Higher Schools in Shanxi(Grant No.J2020383)Teaching Reform and Innovation Project of the Education Department of Shanxi Province(Grant No.J20221195).
文摘Flexible pressure sensors show great promise for applications in such fields as electronic skin,healthcare,and intelligent robotics.Traditional capacitive pressure sensors,however,face the problem of low sensitivity,which limits their wider application.In this paper,a flexible capacitive pressure sensor with microstructured ionization layer is fabricated by a sandwich-type process,with a low-cost and simple process of inverted molding with sandpapers being used to form a thermoplastic polyurethane elastomer ionic film with double-sided microstructure as the dielectric layer of the sensor,with silver nanowires as electrodes.The operating mechanism of this iontronic pressure sensor is analyzed using a graphical method,and the sensor is tested on a pressure platform.The test results show that the sensor has ultrahigh pressure sensitivities of 3.744 and 1.689 kPa^(−1) at low(0-20 kPa)and high(20-800 kPa)pressures,respectively,as well as a rapid response time(100 ms),and it exhibits good stability and repeatability.The sensor can be used for sensitive monitoring of activities such as finger bending,and for facial expression(smile,frown)recognition,as well as speech recognition.
基金the Open Foundation of the State Key Laboratory of Fluid Power and Mechatronic Systems(No.GZKF-202219)the Belt and Road Joint Laboratory on Measurement and Control Technology(No.MCT202306)。
文摘The fexible strain sensor has found widespread application due to its excellent fexibility,extensibility,and adaptability to various scenarios.This type of sensors face challenges in direction identification owing to strong coupling between the principal strain and transverse resistance.In this study,a silver nanowires(Ag-NWs)/polydimethylsiloxane(PDMS)strain sensor was developed,using a filtration method for preparing the AgNWs film which was then combined with PDMS to create a unidirectional,highly sensitive,fast-responsive,and linear fexible strain sensor.When the grid width is 0.25 mm,the AgNWs/PDMS strain sensor demonstrates an outstanding unidirectional sensitivity,with a strain response solely along the parallel direction of the grid lines(noise ratioα≈8%),and a fast reaction time of roughly 106.99 ms.In the end,this sensor's ability to detect curvature was also demonstrated through LEDs,demonstrating its potential applications in various fields,including automotive,medical,and wearable devices.
文摘A rectangular finite element for laminated plate with bonded and/or embedded piezoelectric sensors and actuators is developed based on the variational principle and the first order shear deformation theory. The element has four-node, 20-degrees-of-freedom with one potential degree of freedom for each piezoelectric layer to represent the piezoelectric behavior. The higher order derivation of deflection is obtained by using the normal rotation expressions to take the effects of transverse shear deformation into considerations. The finite element can accurately simulate the deformation of both thin and moderately thick plates. A Fortran program is written and a number of benchmark tests are exercised to verify its effectiveness. Results are compared well with the existing data. The unbalanced composite with piezoelectric layers is then analyzed by using the model. Results show that the changes of the ratio between the thickness of positive angle layers and the negative angle layers have an effect on the deformation of the structure under the same electric loading.
文摘Aim to detect the characteristic weak magnetic field signal against the strong noises background. Methods In combination with a low-pass-filter, the correlation output of magne-* tic sensors between the magnetic field and reference current was utilized to provide a DC output voltage proportional to the applied magnetic induction, computer simulation was* done to investigate the correlation output of the Hall-effect sensors. Results Some analysis results concerning the noise property, harmonic supppression and the sensitivity were given. Conclsion The minimum detection signal of the equipment evolved from the mentioned cor-* relation theory can be 10-6 T. In addition to the DC output, such sensors can also measure the phase of the detected magnetic induction and has good harmonic suppression as well as* noise elimination.
基金Project supported by the National Basic Research Program of China(Grant No.2010CB327601)
文摘We propose a novel high-performance digital optical sensor based on the Mach-Zehnder interferential effect and the dual-microring resonators with the waveguide-coupled feedback. The simulation results show that the sensitivity of the sensor can be orders of magnitude higher than that of aconventional sensor, and high quality factor is not critical in it. Moreover, by optimizing the length of the feedback waveguide to be equal to the perimeter of the ring, the measurement range of the proposed sensor is twice as much as that of the conventional sensor in the weak coupling case.
基金Project supported by the National Key Research and Development Program of China(Grant No.2016YFB0400603)the National Natural Science Foundation of China(Grant No.61804012).
文摘A multi-coating technique of reduced graphene oxide(RGO)was proposed to increase the sensitivity of paper-based pressure sensors.The maximum sensitivity of 17.6 kPa^-1 under the 1.4 kPa was achieved.The electrical sensing mechanism is attributed to the percolation effect.Such paper pressure sensors were applied to monitor the motor vibration,which indicates the potential of mechanical flaw detection by analyzing the waveform difference.
文摘In vibration active control of composite structures, piezoelectricsensors/actuators are usually bonded to the surface of a host structure. Debonding of piezoelectricsensors/actuators can result in significant changes to the static and dynamic response. In thepresent paper, an novel Enhanced Assumed Strain(EAS) piezoelectric solid element formulation isdeveloped for vibration active control of laminated structures bonded with piezoelectric sensors andactuators. Unlike the conventional brick elements, the present formulation is very reliable, moreaccurate, and computationally efficient and can be used to model the response of shell structuresbesides thin plates. Delaminations are modeled by pairs of nodes with the same coordinates butdifferent node numbers, and numerical results demonstrate the performance of the element and theglobal and local effects of debonding sensors/actuators on the dynamics of the adaptive laminates.
基金financially supported by the National Natural Science Foundation of China(No.52173301)International Science and Technology Cooperation Project of Sichuan Province(No.2022YFH0019)Innovative Research Team of Southwest Petroleum University(No.2017CXTD01)。
文摘Flexible hydrogels have shown promise as strain sensors in medical monitoring,human motion detection and intelligent robotics.For a hydrogel strain sensor,certain challenges need to be urgently addressed for practical applications,such as the damage caused by external effects,leading to equipment failure,and the inability to perceive ambient temperature,resulting in single functionality.Herein,a stretchable,self-healing and dual temperature-strain sensitive hydrogel,with a physically-crosslinked network,is designed by constructing multiple dynamic reversible bonds.Graphene oxide(GO)and iron ions(Fe^(3+))act as dynamic bridges in the cross-linked network and are mediated by the covalent and hydrogen bonding,rendering excellent stretchability to the hydrogel.The reversible features of coordination interactions and hydrogen interactions endow excellent recoverability and self-healing properties.Moreover,the incorporated N-isopropyl acrylamide(NIPAM)provides excellent temperature responsiveness to the hydrogel,facilitating the detection of external temperature changes.Meanwhile,the hydrogels exhibited strain-sensitivity,with a wide working range of 1%-300%,fast response and electrical stability,which can be used as flexible sensors to monitor body motions,e.g.,speaking and the bending of finger,wrist,elbow and knee.Overall,the hydrogel possesses dual sensory capabilities,combining external temperature and strain,for potential applications in wearable multifunctional sensing devices.
基金financially supported by the National Natural Science Foundation of China (Nos.22075046,51972063,2150112751502185)+2 种基金Natural Science Funds for Distinguished Young Scholar of Fujian Province (No.2020J06038)Natural Science Foundation of Fujian Province (Nos.2020J01514,2019J01652,and2019J01256)111 Project (No.D17005)。
文摘Highly sensitive pressure sensors are often deployed in human-machine interaction area,touch screen and human motion detection.However,there are still great challenges to fabricating with high sensitivity pressure sensor with wide-range detection.Herein,we developed a new strategy to fabricate a highly sensitive pressure sensor using sandpaper and improve its detection range using a sacrificial template.It was the fthatirst time to combine microstructure processing with the sacrificial template method to fabricate pressure sensor.The microstructure of sandpaper endowed the sensor with high sensitivity,and the elastic substrate enhanced the sensor ability to resist high pressure without being damaged.The fabricated sensor device exhibits a superior sensitivity of 39.077 kPa-1in the range from 50 kPa to 110 kPa with a broad linear response.Remarkably,high pressure ceiling(<160 kPa) ensures that the sponge could be applied in different practical conditions to monitor a range of subtle human motions including finger,wrist bending,and pulse.For applications,the sensor device can not only detect the foot stepping behavior(0.7 MPa) but also produce an obvious response to an extremely slight paper(9 mg,~0.9 Pa).The successful preparation of this micro-structured elastic sponge material provided new ideas for exploring its potential applications in pressure sensors and flexible wearable electronic devices.
基金supported by the National Natural Science Foundation of China(No.61775095)six talent peak innovation team in Jiangsu Province(No.TD-SWYY-009)“Taishan scholars”construction special fund of Shandong Province。
文摘The flourishing development in flexible electronics has provoked intensive research in flexible strain sensors to realize accurate perception acquisition under different external stimuli.However,building hydrogel-based strain sensors with high stretchability and sensitivity remains a great challenge.Herein,MXene nanosheets were composited into polyacrylamide-sodium alginate matrix to construct mechanical robust and sensitive double networked hydrogel strain sensor.The hydrophilic MXene nanosheets formed strong interactions with the polymer matrix and endowed the hydrogel with excellent tensile properties(3150%),compliant mechanical strength(2.03 kPa^(-1)in Young’s Module)and long-lasting stability and fatigue resistance(1000 dynamic cycles under 1,600%strain).Due to the highly oriented MXene-based three dimensional conductive networks,the hydrogel sensor achieved extremely high tensile sensitivity(18.15 in gauge factor)and compression sensitivity(0.38 kPa^(-1)below 3 kPa).MXene hydrogel-based strain sensors also displayed negligible hysteresis in electromechanical performance,typical frequent-independent feature and rapid response time to external stimuli.Moreover,the sensor exhibited accurate response to different scales of human movements,providing potential application in speech recognition,expression recognition and handwriting verification.
基金Project supported by the National Natural Science Foundation of China(51962008)Jiangxi Provincial Natural Science Foundation(20202BABL203018)。
文摘L-kynurenine(L-kyn)is a marker of prostate cancer.At present,the expensive instruments are usually applied to detect L-kyn clinically,which limits its wide application for cancer diagnosis.Herein,three lanthanide metal-organic frameworks([Ln(CHO_(2))_(3)]_(n),Ln=Eu,Gd,and Tb)were designed and obtained,and detailly characterized by single crystal X-ray diffraction(SCXRD),powder X-ray diffraction(PXRD),Fourier transform infrared spectroscopy(FT-IR),thermogravimetric analysis(TGA),and luminescence spectroscopy.Further study reveals that[Tb(CHO_(2))_(3)]_(n)is a highly selective,ultra-sensitive,of strong anti-interference,highly stable,and non-expensive sensor for prostate cancer marker L-kyn.The limit of detection(LOD)for L-kyn sensing is a highly sensitive value of 1.0×10^(−9)mol/L.Furthermore,the sensing mechanism is discussed in detail.
基金supported by National Natural Science Foundation of China under Grants (U1805261 and 22161142024)A~*STAR SERC AME Programmatic Fund (A18A7b0058)
文摘Human–machine interactions using deep-learning methods are important in the research of virtual reality,augmented reality,and metaverse.Such research remains challenging as current interactive sensing interfaces for single-point or multipoint touch input are trapped by massive crossover electrodes,signal crosstalk,propagation delay,and demanding configuration requirements.Here,an all-inone multipoint touch sensor(AIOM touch sensor)with only two electrodes is reported.The AIOM touch sensor is efficiently constructed by gradient resistance elements,which can highly adapt to diverse application-dependent configurations.Combined with deep learning method,the AIOM touch sensor can be utilized to recognize,learn,and memorize human–machine interactions.A biometric verification system is built based on the AIOM touch sensor,which achieves a high identification accuracy of over 98%and offers a promising hybrid cyber security against password leaking.Diversiform human–machine interactions,including freely playing piano music and programmatically controlling a drone,demonstrate the high stability,rapid response time,and excellent spatiotemporally dynamic resolution of the AIOM touch sensor,which will promote significant development of interactive sensing interfaces between fingertips and virtual objects.
基金We are grateful for funding from the Natural Science Foundation of China(NSFC Grant No.62001322)the Tianjin Municipal Science and Technology Project(No.20JCQNJC011200)+1 种基金the National Key Research and Development Program(No.2020YFB2008801)the Nanchang Institute for Microtechnology of Tianjin University.
文摘The World Health Organization has declared COVID-19 a pandemic.The demand for devices or systems to diagnose and track COVID-19 infections noninvasively not only in hospitals but also in home settings has led to increased interest in consumer-grade wearables.A common symptom of COVID-19 is dyspnea,which may manifest as an increase in respiratory and heart rates.In this paper,a novel piezoelectric strain sensor is presented for real-time monitoring of respiratory and heartbeat signals.A highly sensitive and stretchable piezoelectric strain sensor is fabricated using a piezoelectric film with a serpentine layout.The thickness of the patterned PVDF flexible piezoelectric strain sensor is only 168μm,and the voltage sensitivity reaches 0.97 mV/με.The effective modulus is 13.5 MPa,which allows the device to fit to the skin and detect the small strain exhibited by the human body.Chest vibrations are captured by the piezoelectric sensor,which produces an electrical output voltage signal conformally mapped with respiratory–cardiac activities.The separate heart activity and respiratory signals are extracted from the mixed respiratory–cardiac signal by an empirical mode decomposition data processing algorithm.By detecting vital signals such as respiratory and heart rates,the proposed device can aid early diagnosis and monitoring of respiratory diseases such as COVID-19.
文摘The aim of this work is to model and analyze the behavior of a new smart nano force sensor.To do so,the carbon nanotube has been used as a suspended gate of a metal-oxide-semiconductor field-effect transistor(MOSFET).The variation of the applied force on the carbon nanotube(CNT)generates a variation of the capacity of the transistor oxide-gate and therefore the variation of the threshold voltage,which allows the MOSFET to become a capacitive nano force sensor.The sensitivity of the nano force sensor can reach 0.12431V/nN.This sensitivity is greater than results in the literature.We have found through this study that the response of the sensor depends strongly on the geometric and physical parameters of the CNT.From the results obtained in this study,it can be seen that the increase in the applied force increases the value of the MOSFET threshold voltage VTh.In this paper,we first used artificial neural networks to faithfully reproduce the response of the nano force sensor model.This neural model is called direct model.Then,secondly,we designed an inverse model called an intelligent sensor which allows linearization of the response of our developed force sensor.
基金Project supported by the Shanghai Leading Academic Discipline Project (Grant No.S30108)
文摘A novel fiber strain sensor is proposed, based on the two-mode interference of a suspended-core fiber. A fullvectorial finite difference mode solver is employed as the numerical tool for characterizing the proposed strain sensor. The numerical results show that the proposed strain sensor has an estimated sensitivity of 0.05 rad/（m-με）, higher than that of the strain sensors using conventional multimode fibers, while the temperature sensitivity of the proposed sensor is relatively low.
基金financially supported by the National Natural Science Foundation of China(No.11604227)International Visiting Program for Excellent Young Scholars of SCU(No.20181504)International Science and Technology Innovation Cooperation of Sichuan Province(No.21GJHZ0230)。
文摘Chiral metamaterials have been a topic of significant research interest in recent years due to their potential for various applications in nanophotonic devices and chiral biosensors.However,the intrinsic Ohmic loss in surface plasmonic resonance has limited their practical use,resulting in large light dissipation and weak chiroptical resonance.Here,we report on the development of high-performance dielectric chiral shells(DCS)through a two-step Si deposition process on a self-assembled microsphere monolayer.The form DCS sample completely oyercomes the cancelation effect originated from the disorder property of the micro-sphere monolayer in macroscale,and at a wavelength of approximately 710 nm,the measured optimal chiral signal(g-factor)and transmittance can reach up to 0.7 and 0.3,respectively.The strong chiroptical effect comes from the asymmetric circular displacement currents(i.e.,magnetic modes)enabled by the specific shell geometry.The chiral shell geometry,electromagnetic properties,sensor sensitivity of chiral molecules and figure of merit are systematically investigated.The DCSs demonstrate highly sensitive detection of chiral biomolecules owing to their easily accessible geometry and enhanced uniform chiral field.
基金supported by the National Natural Science Foundation of China(No41176081)the Outstanding Youth Natural Science Foundation of Shandong Province(NoJQ200814)the Taishan Scholar Program of Shandong Province(NoTS20081159)
文摘A polymeric membrane ion-selective electrode for determination of heparin is described in this paper.Protamine is incorporated into the organic membrane phase and functions as sensing element for selective recognition of heparin.The proposed membrane electrode exhibits high selectivity for heparin over lipophilic anions such as thiocyanide and salicylate.The potentiometric response to the concentration of heparin is Unear in the range of 0.01-0.4 U/mL and a lower detection limit of 0.005 U/mL can be achieved.
文摘We have demonstrated and analyzed the methane gas sensor based on octagonal cladding and hexagonal hybrid porous core photonic crystal fiber (HPC-PCF) for gas detection purpose. The proposed design of HPC-PCF has been numerically investigated by COMSOL Multiphysics software through utilizing the full vectorial finite element method (FEM). The optical characteristics of HPC-PCF as well as confinement loss, relative sensitivity and refractive index, effective area, nonlinearity and numerical aperture are optimized properly by changing the geometrical parameters as well as air filling ratio, air hole diameter, pitch constant of cladding and porosity of the core. In this simulation work, we have achieved optimum relative sensitivity of 21.2%, and confinement loss of 0.000025 dB/m at 3 μm pitch, 0.7 air filling ratio of the cladding and 29% porosity of the core for 3.5 μm absorption wavelength of CH4 gas. This proposed design of HPC-PCF will keep exclusive contribution for detecting the CH4 gas accurately.
基金Project(2019zzts684)supported by the Fundamental Research Funds for the Central Universities,China。
文摘The highly-dispersed iron element decorated Ni foam was prepared by simple immersion in a ferric nitrate solution at room temperature without using acid etching, and characterized by X-ray powder diffraction(XRD), scanning electron microscopy(SEM), EDAX spectrum(EDAX mapping) and Raman spectroscopy. The EDAX spectrum illustrated that iron element was highly-dispersed over the entire surface of nickel foam, and the Raman spectroscopy revealed that both Ni-O and Fe-O bonds were formed on the surface of the as-prepared electrode. Moreover, the iron element decorated Ni foam electrode can be used as non-enzymatic glucose sensor and it exhibits not only an ultra-wide linear concentration range of 1-18 mmol/L with an outstanding sensitivity of 1.0388 m A·mmol/(L·cm2), but also an excellent ability of stability and selectivity. Therefore, this work presents a simple yet effective approach to successfully modify Ni foam as non-enzymatic glucose sensor.
