Flexible mechanosensors with a high sensitivity and fast response speed may advance the wearable and implantable applications of healthcare devices, such as real-time heart rate, pulse, and respiration monitoring. In ...Flexible mechanosensors with a high sensitivity and fast response speed may advance the wearable and implantable applications of healthcare devices, such as real-time heart rate, pulse, and respiration monitoring. In this paper, we introduce a novel flexible electronic eardrum （EE） based on single-walled carbon nanotubes, polyethylene, and polydimethylsiloxane with micro-structured pyramid arrays. The EE device shows a high sensitivity, high signal-to-noise ratio （approximately 55 dB）, and fast response time （76.9 μs） in detecting and recording sound within a frequency domain of 20-13,000 Hz. The mechanism for sound detection is investigated and the sensitivity is determined using the micro-structure, thickness, and strain state. We also demonstrated that the device is able to distinguish human voices. This unprecedented performance of the flexible electronic eardrum has implications for many applications such as implantable acoustical bioelectronics and personal voice recognition.展开更多
T Parallel wire strands(PWSs),which are widely used in prestressed steel structures,are typically in highstress states.Under fire conditions,significant creep effects occur,reducing the prestress and influencing the m...T Parallel wire strands(PWSs),which are widely used in prestressed steel structures,are typically in highstress states.Under fire conditions,significant creep effects occur,reducing the prestress and influencing the mechanical behavior of PWSs.As there is no existing approach to analyze their creep behavior,this study experimentally investigated the elevated temperature creep model of PWSs.A charge-coupled camera system was incorporated to accurately obtain the deformation of the specimen during the elevated temperature creep test.It was concluded that the temperature level had a more significant effect on the creep strain than the stress level,and 450℃ was the key segment point where the creep rate varied significantly.By comparing the elevated temperature creep test results for PWSs and steel strands,it was found that the creep strain of PWSs was lower than that of steel strands at the same temperature and stress levels.The parameters in the general empirical formula,the Bailey–Norton model,and the composite timehardening model were fitted based on the experimental results.By evaluating the accuracy and form of the models,the composite time-hardening model,which can simultaneously consider temperature,stress,and time,is recommended for use in the fire-resistance design of pre-tensioned structures with PWSs.展开更多
基金We acknowledge the funding support from the National Natural Science Foundation of China （No. 61574163）, the China Postdoctoral Science Foundation （No. 2015M571837） and the Foundation Research Project of Jiangsu Province （No. BK20150364）.
文摘Flexible mechanosensors with a high sensitivity and fast response speed may advance the wearable and implantable applications of healthcare devices, such as real-time heart rate, pulse, and respiration monitoring. In this paper, we introduce a novel flexible electronic eardrum （EE） based on single-walled carbon nanotubes, polyethylene, and polydimethylsiloxane with micro-structured pyramid arrays. The EE device shows a high sensitivity, high signal-to-noise ratio （approximately 55 dB）, and fast response time （76.9 μs） in detecting and recording sound within a frequency domain of 20-13,000 Hz. The mechanism for sound detection is investigated and the sensitivity is determined using the micro-structure, thickness, and strain state. We also demonstrated that the device is able to distinguish human voices. This unprecedented performance of the flexible electronic eardrum has implications for many applications such as implantable acoustical bioelectronics and personal voice recognition.
基金support provided by the National Natural Science Foundation of China(Grant No.51878348)the Shanghai Pujiang Program(No.22PJ1414000).
文摘T Parallel wire strands(PWSs),which are widely used in prestressed steel structures,are typically in highstress states.Under fire conditions,significant creep effects occur,reducing the prestress and influencing the mechanical behavior of PWSs.As there is no existing approach to analyze their creep behavior,this study experimentally investigated the elevated temperature creep model of PWSs.A charge-coupled camera system was incorporated to accurately obtain the deformation of the specimen during the elevated temperature creep test.It was concluded that the temperature level had a more significant effect on the creep strain than the stress level,and 450℃ was the key segment point where the creep rate varied significantly.By comparing the elevated temperature creep test results for PWSs and steel strands,it was found that the creep strain of PWSs was lower than that of steel strands at the same temperature and stress levels.The parameters in the general empirical formula,the Bailey–Norton model,and the composite timehardening model were fitted based on the experimental results.By evaluating the accuracy and form of the models,the composite time-hardening model,which can simultaneously consider temperature,stress,and time,is recommended for use in the fire-resistance design of pre-tensioned structures with PWSs.
