In this paper, we review various types of graphene-based strain sensors. Graphene is a monolayer of carbon atoms, which exhibits prominent electrical and mechanical properties and can be a good candidate in compact st...In this paper, we review various types of graphene-based strain sensors. Graphene is a monolayer of carbon atoms, which exhibits prominent electrical and mechanical properties and can be a good candidate in compact strain sensor ap- plications. However, a perfect graphene is robust and has a low piezoresistive sensitivity. So scientists have been driven to increase the sensitivity using different kinds of methods since the first graphene-based strain sensor was reported. We give a comprehensive review of graphene-based strain sensors with different structures and mechanisms. It is obvious that graphene offers some advantages and has potential for the strain sensor application in the near future.展开更多
The deformation resistance effect of polyacrylonitrile (PAN)-based carbon fibers was investigated, and the variatipn law of electrical resistivity under tensile stress was analyzed. The results show that the gauge f...The deformation resistance effect of polyacrylonitrile (PAN)-based carbon fibers was investigated, and the variatipn law of electrical resistivity under tensile stress was analyzed. The results show that the gauge factor (fractional change in resistance per unit strain) of PAN-based carbon fibers is 1.38, which is lower than that of the commonly-used resistance strain gauge. These may due to that the electrical resistivity of carbon fibers decreases under tensile stress. In addition when the carbon fibers are stretched, the change of its resistance is caused by fiber physical dimension and the change of electric resistivity, and mainly caused by the change of physical dimension. The mechanical properties of carbon fiber monofilament were also measured.展开更多
Karma alloy thin film strain gauges were fabricated on alumina substrates by magnetron sputtering. The electrical properties of strain gauges annealed at different temperatures were then tested. The surface morphology...Karma alloy thin film strain gauges were fabricated on alumina substrates by magnetron sputtering. The electrical properties of strain gauges annealed at different temperatures were then tested. The surface morphology and phase structure of the Karma alloy thin films were analyzed using X-ray diffraction and scanning electron microscopy. The effect of the annealing temperature on the performance of the Karma alloy thin film strain gauge was also investigated. As the annealing temperature increased, it was found that the resistivity of the thin films decreased, whereas the temperature coefficient of resistance (TCR) of the thin films increased. A Karma alloy thin film strain gauge was annealed at 200 °C, thereby obtaining a gauge factor of 1.7 and a corresponding TCR of 64.8 × 10−6 K−1. The prepared Karma alloy thin film strain gauge had a lower TCR than other strain gauges at room temperature. This result can provide a reference for the preparation and application of Karma alloy thin film strain gauges in specific scenarios.展开更多
Based on the trap model, the band structure and the conductive mechanism ofpolysilicon were analyzed, and then an equivalent circuit used to interpret the tunneling piezoresistive effect was proposed. Synthesizing the...Based on the trap model, the band structure and the conductive mechanism ofpolysilicon were analyzed, and then an equivalent circuit used to interpret the tunneling piezoresistive effect was proposed. Synthesizing the piezoresistive effect of the grain boundary region and grain neutral zone, a new piezoresistive model--a tunneling piezoresistive model is established. The results show that when the doping concentration is above 10^20 cm^-3, the piezoresistive coefficient of the grain boundary is higher than that of the neutral zone, and it increases with an increase in doping concentration. This reveals the intrinsic mechanism of an important experimental phenomena that the gauge factor of heavily doped polysilicon nano-films increases with an increase in doping concentration.展开更多
The experiment results indicate that the gauge factor of highly boron doped polysilicon nanofilm is bigger than that of monocrystalline silicon with the same doping concentration, and increases with the grain size dec...The experiment results indicate that the gauge factor of highly boron doped polysilicon nanofilm is bigger than that of monocrystalline silicon with the same doping concentration, and increases with the grain size decreasing. To apply the unique properties reasonably in the fabrication of piezoresistive devices, it was expounded based on the analysis of energy band structure that the properties were caused by the tunnel current which varies with the strain change forming a tunnelling piezoresistive effect. Finally, a calculation method ofpiezoresistance coefficients around grain boundaries was presented, and then the experiment results ofpolysilicon nanofilms were explained theoretically.展开更多
基金Project supported by the National Basic Research Program of China (Grant No. 2013CB934500)the National Natural Science Foundation of China (Grant No. 91223204)
文摘In this paper, we review various types of graphene-based strain sensors. Graphene is a monolayer of carbon atoms, which exhibits prominent electrical and mechanical properties and can be a good candidate in compact strain sensor ap- plications. However, a perfect graphene is robust and has a low piezoresistive sensitivity. So scientists have been driven to increase the sensitivity using different kinds of methods since the first graphene-based strain sensor was reported. We give a comprehensive review of graphene-based strain sensors with different structures and mechanisms. It is obvious that graphene offers some advantages and has potential for the strain sensor application in the near future.
基金Funded by the National Natural Science Foundation of China (No.10672128 and 50878170)
文摘The deformation resistance effect of polyacrylonitrile (PAN)-based carbon fibers was investigated, and the variatipn law of electrical resistivity under tensile stress was analyzed. The results show that the gauge factor (fractional change in resistance per unit strain) of PAN-based carbon fibers is 1.38, which is lower than that of the commonly-used resistance strain gauge. These may due to that the electrical resistivity of carbon fibers decreases under tensile stress. In addition when the carbon fibers are stretched, the change of its resistance is caused by fiber physical dimension and the change of electric resistivity, and mainly caused by the change of physical dimension. The mechanical properties of carbon fiber monofilament were also measured.
文摘Karma alloy thin film strain gauges were fabricated on alumina substrates by magnetron sputtering. The electrical properties of strain gauges annealed at different temperatures were then tested. The surface morphology and phase structure of the Karma alloy thin films were analyzed using X-ray diffraction and scanning electron microscopy. The effect of the annealing temperature on the performance of the Karma alloy thin film strain gauge was also investigated. As the annealing temperature increased, it was found that the resistivity of the thin films decreased, whereas the temperature coefficient of resistance (TCR) of the thin films increased. A Karma alloy thin film strain gauge was annealed at 200 °C, thereby obtaining a gauge factor of 1.7 and a corresponding TCR of 64.8 × 10−6 K−1. The prepared Karma alloy thin film strain gauge had a lower TCR than other strain gauges at room temperature. This result can provide a reference for the preparation and application of Karma alloy thin film strain gauges in specific scenarios.
基金supported by the National Natural Science Foundation of China(No.60776049)the Science and Technology Foundation of Liaoning Province(No.20072036)the Fund of Liaoning Province Education Department(No.2007T130)
文摘Based on the trap model, the band structure and the conductive mechanism ofpolysilicon were analyzed, and then an equivalent circuit used to interpret the tunneling piezoresistive effect was proposed. Synthesizing the piezoresistive effect of the grain boundary region and grain neutral zone, a new piezoresistive model--a tunneling piezoresistive model is established. The results show that when the doping concentration is above 10^20 cm^-3, the piezoresistive coefficient of the grain boundary is higher than that of the neutral zone, and it increases with an increase in doping concentration. This reveals the intrinsic mechanism of an important experimental phenomena that the gauge factor of heavily doped polysilicon nano-films increases with an increase in doping concentration.
基金supported by the National Natural Science Foundation of China(No.60776049)the Science and Technology Foundation of Liaoning Province ofChina(No.20072036)the Fund ofLiaoning Province Education Department of China(No.2007T130).
文摘The experiment results indicate that the gauge factor of highly boron doped polysilicon nanofilm is bigger than that of monocrystalline silicon with the same doping concentration, and increases with the grain size decreasing. To apply the unique properties reasonably in the fabrication of piezoresistive devices, it was expounded based on the analysis of energy band structure that the properties were caused by the tunnel current which varies with the strain change forming a tunnelling piezoresistive effect. Finally, a calculation method ofpiezoresistance coefficients around grain boundaries was presented, and then the experiment results ofpolysilicon nanofilms were explained theoretically.