title: A capacitive-pulse model for nanoparticle sensing by single conical nanochannels.
abstract: Nanochannel based devices have been widely used for single-molecule detection. The detection usually relies on the resistive-pulse model, where the change of the monitored current depends on the physical volumetric blocking of the nanochannel by the analyte. However, this mechanism requires that the nanochannel diameter should not be much larger than the analyte size, because, otherwise, the resultant current change would be too small to detect, and therefore poses particular challenges for the fabrication of nanochannels. To circumvent this issue, in this report, we propose a different mechanism of capacitive-pulse model, where the transport signals can be significantly magnified by the capacitive effect of the nanochannel. We experimentally demonstrate that current pulses with an averaged peak height of 0.87 nA can be achieved for transporting 60 nm nanoparticles through a conical nanochannel device, whereas the traditional resistive-pulse model only predicts one-order-of-magnitude lowered value. With further comprehensive simulation, the dependence of this effect on the nanochannel geometry as well as the surface charge density for both the nanochannel and the analyte is predicted, which would provide important guidance for better designing of the nanochannel-based sensors.
authors.affiliation: State Key Laboratory of Nuclear Physics and Technology, School of Physics, Peking University, Beijing 100871, People's Republic of China.
authors.forename: Qian
authors.initials: Q
authors.lastname: Sheng
authors.affiliation: School of Advanced Materials, Peking University Shenzhen Graduate School, Shenzhen 518055, People's Republic of China. wangxw@pkusz.edu.cn.
authors.forename: Xinwei
authors.initials: X
authors.lastname: Wang
authors.affiliation: Department of Applied Physics, School of Science, Northwestern Polytechnical University, Xi'an 710072, People's Republic of China.
authors.forename: Yanbo
authors.initials: Y
authors.lastname: Xie
authors.affiliation: State Key Laboratory of Nuclear Physics and Technology, School of Physics, Peking University, Beijing 100871, People's Republic of China.
authors.forename: Ceming
authors.initials: C
authors.lastname: Wang
authors.affiliation: State Key Laboratory of Nuclear Physics and Technology, School of Physics, Peking University, Beijing 100871, People's Republic of China and Center for Applied Physics and Technology, Peking University, Beijing 100871, People's Republic of China. jmxue@pku.edu.cn.
authors.forename: Jianming
authors.initials: J
authors.lastname: Xue