Modeling the Influence of the Edge Electrostatic Effect on the Transformation Function of Thin-Film Quasi-Differential Capacitive Sensitive Elements

Capacitive sensing elements are the main components of capacitive measuring transducers, which determine most of the metrological characteristics and operational parameters of sensors. First of all, capacitive sensing elements ensure the temporal and parametric stability of sensors, which are the main operational characteristics in such areas as rocket and space and aviation technology, the nuclear industry, in which the instability of sensors and measuring systems based on them can lead to high financial and human losses. etc. At the same time, compensation for lateral capacitive couplings and electrostatic leaks are very important issues, since small changes in capacitance when measuring physical quantities can lead to uninformative measurements in the presence of distortion of electrostatic fields in a capacitive sensing element. In this regard, it is necessary to take into account and simulate the stray fields of electrostatic fields and their influence on measurements.

Simulations on Simple Models of Connexin Hemichannels Indicate That Ca2+ Blocking Is Not a Pure Electrostatic Effect

Connexin hemichannels allow the unspecific but regulated interchange of molecules from ions to second messenger and ATP, between the eukariotic cell and its extracellular space. The transport of ions and water through hemichannels is important for physiological functions and also in the progression of several pathological conditions. Extracellular Ca2+ concentration is one of the regulators that drives the channel to a closed state. However the relation between their functional and structural states is far for being totally understood. In this work, we modelled connexin hemichannels using simple systems based on a fixed array of carbon atoms and assess the Ca2+ regulation using molecular dynamics simulations. The two proposed mechanism described so far for calcium action were studied combined, e.g., an electrostatic effect and a pore stretching. Our results show that the addition of positive charge density inside the channel cannot stop the flow of potassium, chloride nor water. Only a pore stretching at the center of the pore can explain the channel blocking.

Electrostatic Circular Membrane MEMS: An Approach to the Optimal Control

The recovery of the membrane profile of an electrostatic micro-electro-mechanical system (MEMS) is an important issue, because, when an external electrical voltage is applied, the membrane deforms with the risk of touching the upper plate of the device producing an unwanted electrostatic effect. Therefore, it is important to know whether the movement admits stable equilibrium configurations especially when the membrane is closed to the upper plate. In this framework, this work analyzes the behavior of a two-dimensional (2D) electrostatic circular membrane MEMS device subjected to an external voltage. Specifically, starting from a well-known 2D non-linear second-order differential model in which the electrostatic field in the device is proportional to the mean curvature of the membrane, the stability of the only possible equilibrium configuration is studied. Furthermore, when considering that the membrane is equipped with mechanical inertia and that it must not touch the upper plate of the device, a useful range of possible values has been obtained for the applied voltage. Finally, the paper concludes with some computations regarding the variation of potential energy, identifying some optimal control conditions.

Exploring the contribution of charge species at outer surface to ion current signal of nanopores: a theoretical study

Nanopores attached with charge species realize artificial regulation of ion transports by the electrostatic effect in nanoconfines, which produces sensitive ion current signal and plays a critical role in nanopore-based...