Nanocomposite dielectrics show great promising application in developing next generation wearable all-solidstate cooling devices owing to the possessed advantages of high cooling efficiency, light-weight and small vol...Nanocomposite dielectrics show great promising application in developing next generation wearable all-solidstate cooling devices owing to the possessed advantages of high cooling efficiency, light-weight and small volume without the induced greenhouse effect or serious harm to ozone layer in the exploited refrigerants. However, low electrocaloric strength in nanocomposite dielectric is severely restricting its wide-spread application because of high applied operating voltage to improve electrocaloric effect. After addressing the chosen optimized ferroelectric ceramic and ferroelectric polymer matrix in conjunction with the analysis of crucial parameters, recent progress of electrocaloric effect(ECE) in polymer nanocomposites has been considerably reviewed. Subsequently, prior to proposing the conceptual design and devices/systems in electrocaloric nanocomposites, the existing developed devices/systems are reviewed. Finally, conclusions and prospects are conducted, including the aspects of materials chosen, structural design and key issues to be considered in improving electrocaloric effect of polymer nanocomposite dielectrics for flexible solidstate cooling devices.展开更多
Ni0.5Zn0.5Fe2-xCrxO4(0≤x≤0.5)ferrites were successfully prepared by conventional solid state reaction method to investigate the effect of chromium substitution on the structural,electrical and magnetic properties.X-...Ni0.5Zn0.5Fe2-xCrxO4(0≤x≤0.5)ferrites were successfully prepared by conventional solid state reaction method to investigate the effect of chromium substitution on the structural,electrical and magnetic properties.X-ray powder diffraction results demonstrate that all the prepared samples are well crystallized single-phase spinel structures without secondary phase.As chromium concentration increases,the lattice parameter and crystallite size gradually decrease.The magnetic measurement indicates that saturation magnetization is substantially suppressed by Cr3+doping,changing from 73.5 A·m2/kg at x=0 to 46.3 A·m2/kg at x=0.5.While the room-temperature electrical resistivity is more than four orders of magnitude enhanced by Cr3+substitution,reaching up to 1.1×108Ω·cm at x=0.5.The dielectric constant monotonously decreases with rising frequency for these ferrites,showing a normal dielectric dispersion behavior.The compositional dependence of dielectric constant is inverse with that of electrical resistivity,which originates from the reduced Fe2+/Fe3+electric dipole number by doping,indicating inherent correlation between polarization and conduction mechanism in ferrite.展开更多
A two-dimensional photonic crystal with a one-dimensional periodic dielectric background is proposed. The photonic band modulation effects due to the periodic background are investigated based on the plane wave expans...A two-dimensional photonic crystal with a one-dimensional periodic dielectric background is proposed. The photonic band modulation effects due to the periodic background are investigated based on the plane wave expansion method. We find that periodic modulation of the dielectric background greatly alters photonic band structures, especially for the E-polarization modes. The number, width and position of the photonic band gaps （PBGs） sensitively depend on the structure parameters （the layer thicknesses and dielectric constants） of the one-dimensional periodic background,展开更多
Aiming at developing novel microwave-transparent ceramics with low dielectric loss, high thermal conductivity and high strength, Si3Na-AIN （30%, mass fraction） composite ceramics with La203 as sintering additive wer...Aiming at developing novel microwave-transparent ceramics with low dielectric loss, high thermal conductivity and high strength, Si3Na-AIN （30%, mass fraction） composite ceramics with La203 as sintering additive were prepared by hot-pressing at 1 800 ℃ and subsequently annealed at 1 450 ℃ and 1 850 ℃ for 2 h and 4 h, respectively. The materials were characterized by XRD and SEM. The effect of annealing process on the phase composition, sintering performance, microstructure, bending strength, dielectric loss and thermal conductivity of the materials was investigated. The results showed that both annealing at 1 850 ℃ and 1 450 ℃ promoted the phase transformation of α-Si3N4 to β-Si3N4. After annealing at 1 850 ℃, grain growth to a certain extent occurred in the materials. Especially, the elongated β-Si3N4 grains showed a slight increase in diameter from 0.2 μm to 0.6 μm approximately and a decrease in aspect ratio. As a result, as the annealing time increased to 4 h, the bending strength declined from 456 MPa to 390 MPa, whereas the dielectric loss decreased to 2.15× 10^-3 and the thermal conductivity increased to 16.3 W/（m.K） gradually. When annealed at 1 450 ℃, increasing the annealing time to 4 h significantly promoted the crystallization of glassy phase to La2Si6N803 phase in the materials, which led to the increase in bending strength to 619 MPa and thermal conductivity to 15.9 W/（m·K）, respectively, and simultaneously the decrease in dielectric loss to 1.53× 10^-3.展开更多
AC and DC breakdown tests were performed on large populations of oil-impregnated pressboard samples. The effect of voltage ramp rate on dielectric strength has been investigated. A statistical analysis of breakdown da...AC and DC breakdown tests were performed on large populations of oil-impregnated pressboard samples. The effect of voltage ramp rate on dielectric strength has been investigated. A statistical analysis of breakdown data was carried out using the Weibull distribution. The 90% confidence intervals of Weibull graphs were calculated. The study shows that dielectric strength and shape parameter change versus ramp rate. The variations are attributed to the size and number of defects. Discharges occur from the oil to the oil-pressboard interface and lead to breakdown. DC dielectric strength is larger than that corresponding to AC voltage. This is ascribed to the dissipated energy difference under the two types of field and the fatigue produced by the alternating voltage. This phenomenon is related to space charge. Under DC stress, dielectric strength is higher under negative polarity. It is assigned to the different quantities of space charge accumulated under the two polarities.展开更多
The silica fiber reinforced silica and boron nitride-based composites （SiO2f/SiO2-BN） were prepared firstly via the sol-gel method and then the urea route, and the effects of oxidation treatment on the component, st...The silica fiber reinforced silica and boron nitride-based composites （SiO2f/SiO2-BN） were prepared firstly via the sol-gel method and then the urea route, and the effects of oxidation treatment on the component, structure, mechanical and dielectric properties of the composites were investigated. The results show that the oxidation treatment at 450 ℃ will not impair the structure of boron nitride, and carbon is the main impurity with the excessive urea. The density of SiO2f/SiO2-BN composites is 1.81 g/cm3, and the flexural strength and elastic modulus are 113.9 MPa and 36.5 GPa, respectively. After oxidation treatment, the density varies to 1.80 g/cm3, and the flexural strength and elastic modulus are decreased to 58.9 MPa and 9.4 GPa, respectively. The mechanical properties of the composites are severely damaged, but they still exhibit a good toughness. The composites show excellent dielectric properties with the dielectric constant and loss tangent being 3.22 and 0.003 9, respectively, which indicates that the oxidation treatment is ineffective to improve the dielectric properties of SiOzf/SiO2-BN composites.展开更多
Wave propagation in an infinite elastic piezoelectric medium with a circular cavity and an impermeable crack subjected to steady-state anti-plane shearing was studied based on Green's function and the crack-divisi...Wave propagation in an infinite elastic piezoelectric medium with a circular cavity and an impermeable crack subjected to steady-state anti-plane shearing was studied based on Green's function and the crack-division technique.Theoretical solutions were derived for the whole elastic displacement and electric potential field in the interaction between the circular cavity and the impermeable crack.Expressions were obtained on the dynamic stress concentration factor(DSCF) at the cavity's edge,the dynamic stress intensity factor(DSIF) and the dynamic electric displacement intensity factor(DEDIF) at the crack tip.Numerical solutions were performed and plotted with different incident wave numbers,parameters of piezoelectric materials and geometries of the structure.Finally,some of the calculation results were compared with the case of dynamic anti-plane interaction of a permeable crack and a circular cavity in an infinite piezoelectric medium.This paper can provide a valuable reference for the design of piezoelectric actuators and sensors widely used in marine structures.展开更多
The electrical, physical, mechanical and thermal properties of fluorine-containing alicyclic polyimides have been investigated. It was shown that the minimum value of the dielectric constant 1.91 at room temperature a...The electrical, physical, mechanical and thermal properties of fluorine-containing alicyclic polyimides have been investigated. It was shown that the minimum value of the dielectric constant 1.91 at room temperature and 1 kHz frequency was achieved for polymers containing only one fluorine atom in the structure. The dielectric loss tangent of new polymers was （I -4）~ 103. Electro-physical parameters were stable during polymer heating up to 300 ~C, and at the frequency from 1 to 20 kHz. Resistivity by heating in the air up to 320-380 ~C has been investigated depending on the polyimides structure. The coefficient of moisture absorption for the fluorine-containing polyimide based on dianhydride with 4,4＇-oxydianiline was determined at 50% humidity and 25 ℃. It was around 0.6, but after immersion in the water for 24 and 48 h was 0.8% and 1.2%, respectively. Manufactured films had tensile strength to 160-170 MPa, and elongation up to 55%.展开更多
Relaxor ferroelectric polymers display great potential in capacitor dielectric applications because of their excellent flexibility,light weight,and high dielectric constant.However,their electrical energy storage capa...Relaxor ferroelectric polymers display great potential in capacitor dielectric applications because of their excellent flexibility,light weight,and high dielectric constant.However,their electrical energy storage capacity is limited by their high conduction losses and low dielectric strength,which primarily originates from the impact-ionization-induced electron multiplication,low mechanical modulus,and low thermal conductivity of the dielectric polymers.Here a matrix free strategy is developed to effectively suppress electron multiplication effects and to enhance mechanical modulus and thermal conductivity of a dielectric polymer,which involves the chemical adsorption of an electron barrier layer on boron nitride nanosheet surfaces by chemically adsorbing an amino-containing polymer.A dramatic decrease of leakage current(from 2.4×10^(-6)to 1.1×10^(-7)A cm^(-2)at 100 MV m^(-1))and a substantial increase of breakdown strength(from 340 to 742 MV m^(-1))were achieved in the nanocompostes,which result in a remarkable increase of discharge energy density(from 5.2 to 31.8 J cm^(-3)).Moreover,the dielectric strength of the nanocomposites suffering an electrical breakdown could be restored to 88%of the original value.This study demonstrates a rational design for fabricating dielectric polymer nanocomposites with greatly enhanced electric energy storage capacity.展开更多
In c-C4F8 and c-C4F8/CO2 mixtures, the swarm parameters including ionization coefficient, attachment coefficient and effective ionization coefficient were obtained at the ratio of the electric field strength to the ga...In c-C4F8 and c-C4F8/CO2 mixtures, the swarm parameters including ionization coefficient, attachment coefficient and effective ionization coefficient were obtained at the ratio of the electric field strength to the gas density between 150-550 Td by the steady-state Townsend （SST） method. Static breakdown voltages at each ratio were also measured at the SST condition. The limiting field strengths were obtained by two methods： computing the density-normalized effective ionization coefficient as a function of the overall density-reduced electric field strength; and measuring static breakdown voltages as a function of the product of gas density and electrode separation. Good agreement was obtained by these two methods, which ensures the correctness of the former method. The limiting field strengths of c-C4F8 and c-C4F8/CO2 mixtures were compared with those of pure SF6, 8F6/602 mixtures and pure c-C4F8. It is found that buffer gas CO2 does not reduce the limiting field strengths of c-C4F8 greatly, the limiting field strengths of c-C4F8/CO2 mixtures are higher than those of SF6/CO2 mixtures or even pure SF6, and so c-C4F8/CO2 mixtures are suggested to be possible substitutes for SF6.展开更多
This paper reports a microfluidic method of continuous separation of marine algae and particles by DC dielectrophoresis. The locally non-uniform electric field is generated by an insulating PDMS triangle hurdle fabric...This paper reports a microfluidic method of continuous separation of marine algae and particles by DC dielectrophoresis. The locally non-uniform electric field is generated by an insulating PDMS triangle hurdle fabricated within a PDMS microchannel. Both the particles and algae are subject to negative DEP forces at the hurdle where the gradient of local electric-field strength is the strongest. The DEP force acting on the particle or the algae depends on particles' or algae's volume, shape and dielectric properties. Thus the moving particles and algae will be repelled to different streamlines when passing the hurdle. In this way, combined with the electroosmotic flow, continuous separation of algae of two different sizes, and continuous separation of polystyrene particles and algae with similar volume but different shape were achieved. This first demonstration of DC DEP separation of polystyrene particles and algae with similar sizes illustrates the great influence of dielectric properties on particle separation and potentials for sample pretreatment.展开更多
A series of isometric,radially expanding tubular units,made of dielectric elastomer with compliant electrodes,constitute a soft linear peristaltic pump with distributed actuation for transport of incompressible fluids...A series of isometric,radially expanding tubular units,made of dielectric elastomer with compliant electrodes,constitute a soft linear peristaltic pump with distributed actuation for transport of incompressible fluids.Based on the Gent strain energy model,this paper theoretically analyzes the homogeneous large deformation of the peristaltic unit.We discuss the effects of axial prestretch on the actuation of the actuator.We then predict the maximum actuation strain of this actuator which is limited by dielectric strength of the polymer.The results presented here extend the previous study based on linear elasticity,and can predict the electromechanical behaviors of the novel actuator at large deformations.展开更多
基金Project(202045007) supported by the Start-up Funds for Outstanding Talents in Central South University,China。
文摘Nanocomposite dielectrics show great promising application in developing next generation wearable all-solidstate cooling devices owing to the possessed advantages of high cooling efficiency, light-weight and small volume without the induced greenhouse effect or serious harm to ozone layer in the exploited refrigerants. However, low electrocaloric strength in nanocomposite dielectric is severely restricting its wide-spread application because of high applied operating voltage to improve electrocaloric effect. After addressing the chosen optimized ferroelectric ceramic and ferroelectric polymer matrix in conjunction with the analysis of crucial parameters, recent progress of electrocaloric effect(ECE) in polymer nanocomposites has been considerably reviewed. Subsequently, prior to proposing the conceptual design and devices/systems in electrocaloric nanocomposites, the existing developed devices/systems are reviewed. Finally, conclusions and prospects are conducted, including the aspects of materials chosen, structural design and key issues to be considered in improving electrocaloric effect of polymer nanocomposite dielectrics for flexible solidstate cooling devices.
基金Project(11604147)supported by the National Natural Science Foundation of ChinaProject(M32048)supported by the Foundation of National Laboratory of Solid State Microstructures,ChinaProject(20142BBE50014)supported by the Jiangxi Province Key Projects of Science and Technology Support Plan,China。
文摘Ni0.5Zn0.5Fe2-xCrxO4(0≤x≤0.5)ferrites were successfully prepared by conventional solid state reaction method to investigate the effect of chromium substitution on the structural,electrical and magnetic properties.X-ray powder diffraction results demonstrate that all the prepared samples are well crystallized single-phase spinel structures without secondary phase.As chromium concentration increases,the lattice parameter and crystallite size gradually decrease.The magnetic measurement indicates that saturation magnetization is substantially suppressed by Cr3+doping,changing from 73.5 A·m2/kg at x=0 to 46.3 A·m2/kg at x=0.5.While the room-temperature electrical resistivity is more than four orders of magnitude enhanced by Cr3+substitution,reaching up to 1.1×108Ω·cm at x=0.5.The dielectric constant monotonously decreases with rising frequency for these ferrites,showing a normal dielectric dispersion behavior.The compositional dependence of dielectric constant is inverse with that of electrical resistivity,which originates from the reduced Fe2+/Fe3+electric dipole number by doping,indicating inherent correlation between polarization and conduction mechanism in ferrite.
基金supported by the State Key Basic Research Program of China under Grant No.2006CB921607China-Australia Special Fund for Science and Technology
文摘A two-dimensional photonic crystal with a one-dimensional periodic dielectric background is proposed. The photonic band modulation effects due to the periodic background are investigated based on the plane wave expansion method. We find that periodic modulation of the dielectric background greatly alters photonic band structures, especially for the E-polarization modes. The number, width and position of the photonic band gaps （PBGs） sensitively depend on the structure parameters （the layer thicknesses and dielectric constants） of the one-dimensional periodic background,
基金Project(50872052) supported by the National Natural Science Foundation of ChinaProject(2009AA05Z313) supported by the National High Technology Research and Development Program of ChinaProject supported by the Commission of Science,Technology and Industry for National Defence,China
文摘Aiming at developing novel microwave-transparent ceramics with low dielectric loss, high thermal conductivity and high strength, Si3Na-AIN （30%, mass fraction） composite ceramics with La203 as sintering additive were prepared by hot-pressing at 1 800 ℃ and subsequently annealed at 1 450 ℃ and 1 850 ℃ for 2 h and 4 h, respectively. The materials were characterized by XRD and SEM. The effect of annealing process on the phase composition, sintering performance, microstructure, bending strength, dielectric loss and thermal conductivity of the materials was investigated. The results showed that both annealing at 1 850 ℃ and 1 450 ℃ promoted the phase transformation of α-Si3N4 to β-Si3N4. After annealing at 1 850 ℃, grain growth to a certain extent occurred in the materials. Especially, the elongated β-Si3N4 grains showed a slight increase in diameter from 0.2 μm to 0.6 μm approximately and a decrease in aspect ratio. As a result, as the annealing time increased to 4 h, the bending strength declined from 456 MPa to 390 MPa, whereas the dielectric loss decreased to 2.15× 10^-3 and the thermal conductivity increased to 16.3 W/（m.K） gradually. When annealed at 1 450 ℃, increasing the annealing time to 4 h significantly promoted the crystallization of glassy phase to La2Si6N803 phase in the materials, which led to the increase in bending strength to 619 MPa and thermal conductivity to 15.9 W/（m·K）, respectively, and simultaneously the decrease in dielectric loss to 1.53× 10^-3.
文摘AC and DC breakdown tests were performed on large populations of oil-impregnated pressboard samples. The effect of voltage ramp rate on dielectric strength has been investigated. A statistical analysis of breakdown data was carried out using the Weibull distribution. The 90% confidence intervals of Weibull graphs were calculated. The study shows that dielectric strength and shape parameter change versus ramp rate. The variations are attributed to the size and number of defects. Discharges occur from the oil to the oil-pressboard interface and lead to breakdown. DC dielectric strength is larger than that corresponding to AC voltage. This is ascribed to the dissipated energy difference under the two types of field and the fatigue produced by the alternating voltage. This phenomenon is related to space charge. Under DC stress, dielectric strength is higher under negative polarity. It is assigned to the different quantities of space charge accumulated under the two polarities.
基金Projects(50902150,90916019) supported by the National Natural Science Foundation of ChinaProject (9140C8203040905) supported by the State Key Laboratory Foundation of ChinaProject(S100103) supported by the Graduate Innovation Foundation of National University of Defense Technology,China
文摘The silica fiber reinforced silica and boron nitride-based composites （SiO2f/SiO2-BN） were prepared firstly via the sol-gel method and then the urea route, and the effects of oxidation treatment on the component, structure, mechanical and dielectric properties of the composites were investigated. The results show that the oxidation treatment at 450 ℃ will not impair the structure of boron nitride, and carbon is the main impurity with the excessive urea. The density of SiO2f/SiO2-BN composites is 1.81 g/cm3, and the flexural strength and elastic modulus are 113.9 MPa and 36.5 GPa, respectively. After oxidation treatment, the density varies to 1.80 g/cm3, and the flexural strength and elastic modulus are decreased to 58.9 MPa and 9.4 GPa, respectively. The mechanical properties of the composites are severely damaged, but they still exhibit a good toughness. The composites show excellent dielectric properties with the dielectric constant and loss tangent being 3.22 and 0.003 9, respectively, which indicates that the oxidation treatment is ineffective to improve the dielectric properties of SiOzf/SiO2-BN composites.
基金Supported by the Natural Science Foundation of Heilongjiang Province of China (A00-10)the Basis Research Foundation of Harbin Engineering University (HEUF04008)
文摘Wave propagation in an infinite elastic piezoelectric medium with a circular cavity and an impermeable crack subjected to steady-state anti-plane shearing was studied based on Green's function and the crack-division technique.Theoretical solutions were derived for the whole elastic displacement and electric potential field in the interaction between the circular cavity and the impermeable crack.Expressions were obtained on the dynamic stress concentration factor(DSCF) at the cavity's edge,the dynamic stress intensity factor(DSIF) and the dynamic electric displacement intensity factor(DEDIF) at the crack tip.Numerical solutions were performed and plotted with different incident wave numbers,parameters of piezoelectric materials and geometries of the structure.Finally,some of the calculation results were compared with the case of dynamic anti-plane interaction of a permeable crack and a circular cavity in an infinite piezoelectric medium.This paper can provide a valuable reference for the design of piezoelectric actuators and sensors widely used in marine structures.
文摘The electrical, physical, mechanical and thermal properties of fluorine-containing alicyclic polyimides have been investigated. It was shown that the minimum value of the dielectric constant 1.91 at room temperature and 1 kHz frequency was achieved for polymers containing only one fluorine atom in the structure. The dielectric loss tangent of new polymers was （I -4）~ 103. Electro-physical parameters were stable during polymer heating up to 300 ~C, and at the frequency from 1 to 20 kHz. Resistivity by heating in the air up to 320-380 ~C has been investigated depending on the polyimides structure. The coefficient of moisture absorption for the fluorine-containing polyimide based on dianhydride with 4,4＇-oxydianiline was determined at 50% humidity and 25 ℃. It was around 0.6, but after immersion in the water for 24 and 48 h was 0.8% and 1.2%, respectively. Manufactured films had tensile strength to 160-170 MPa, and elongation up to 55%.
基金supported by the National Natural Science Foundation of China(52003153,51877132 and 52002300)Program of Shanghai Academic Research Leader(21XD1401600)+1 种基金State Key Laboratory of Electrical Insulation and Power Equipment(EIPE20203,EIPE21206)the Major Research Plan of National Natural Science Foundation of China(92066103)。
文摘Relaxor ferroelectric polymers display great potential in capacitor dielectric applications because of their excellent flexibility,light weight,and high dielectric constant.However,their electrical energy storage capacity is limited by their high conduction losses and low dielectric strength,which primarily originates from the impact-ionization-induced electron multiplication,low mechanical modulus,and low thermal conductivity of the dielectric polymers.Here a matrix free strategy is developed to effectively suppress electron multiplication effects and to enhance mechanical modulus and thermal conductivity of a dielectric polymer,which involves the chemical adsorption of an electron barrier layer on boron nitride nanosheet surfaces by chemically adsorbing an amino-containing polymer.A dramatic decrease of leakage current(from 2.4×10^(-6)to 1.1×10^(-7)A cm^(-2)at 100 MV m^(-1))and a substantial increase of breakdown strength(from 340 to 742 MV m^(-1))were achieved in the nanocompostes,which result in a remarkable increase of discharge energy density(from 5.2 to 31.8 J cm^(-3)).Moreover,the dielectric strength of the nanocomposites suffering an electrical breakdown could be restored to 88%of the original value.This study demonstrates a rational design for fabricating dielectric polymer nanocomposites with greatly enhanced electric energy storage capacity.
基金the National Natural Science Foundation of China (No. 50777041)
文摘In c-C4F8 and c-C4F8/CO2 mixtures, the swarm parameters including ionization coefficient, attachment coefficient and effective ionization coefficient were obtained at the ratio of the electric field strength to the gas density between 150-550 Td by the steady-state Townsend （SST） method. Static breakdown voltages at each ratio were also measured at the SST condition. The limiting field strengths were obtained by two methods： computing the density-normalized effective ionization coefficient as a function of the overall density-reduced electric field strength; and measuring static breakdown voltages as a function of the product of gas density and electrode separation. Good agreement was obtained by these two methods, which ensures the correctness of the former method. The limiting field strengths of c-C4F8 and c-C4F8/CO2 mixtures were compared with those of pure SF6, 8F6/602 mixtures and pure c-C4F8. It is found that buffer gas CO2 does not reduce the limiting field strengths of c-C4F8 greatly, the limiting field strengths of c-C4F8/CO2 mixtures are higher than those of SF6/CO2 mixtures or even pure SF6, and so c-C4F8/CO2 mixtures are suggested to be possible substitutes for SF6.
基金support from the Fundamental Research Funds for the Central Universities (2011QN105, 2011ZD014)the Dalian Science and Technology Foundation (2011J21DW005) to SONG YongXin+2 种基金National Science & Technology Pillar Program of China in 2010 (2010BAC68B02)Liaoning Science & Technology Program (2007405010) to SUN YeQingthe Natural Sciences and Engineering Research Council of Canada through a research grant to LI DongQing
文摘This paper reports a microfluidic method of continuous separation of marine algae and particles by DC dielectrophoresis. The locally non-uniform electric field is generated by an insulating PDMS triangle hurdle fabricated within a PDMS microchannel. Both the particles and algae are subject to negative DEP forces at the hurdle where the gradient of local electric-field strength is the strongest. The DEP force acting on the particle or the algae depends on particles' or algae's volume, shape and dielectric properties. Thus the moving particles and algae will be repelled to different streamlines when passing the hurdle. In this way, combined with the electroosmotic flow, continuous separation of algae of two different sizes, and continuous separation of polystyrene particles and algae with similar volume but different shape were achieved. This first demonstration of DC DEP separation of polystyrene particles and algae with similar sizes illustrates the great influence of dielectric properties on particle separation and potentials for sample pretreatment.
基金supported by the National Natural Science Foundation of China (Grant Nos. 11102149,10872157,11072185,and 10972174)
文摘A series of isometric,radially expanding tubular units,made of dielectric elastomer with compliant electrodes,constitute a soft linear peristaltic pump with distributed actuation for transport of incompressible fluids.Based on the Gent strain energy model,this paper theoretically analyzes the homogeneous large deformation of the peristaltic unit.We discuss the effects of axial prestretch on the actuation of the actuator.We then predict the maximum actuation strain of this actuator which is limited by dielectric strength of the polymer.The results presented here extend the previous study based on linear elasticity,and can predict the electromechanical behaviors of the novel actuator at large deformations.
