In the search for gas sensing materials, two-dimensional materials offer the possibility of designing sensors capable of tuning the electronic band structure by controlling their thickness, quantity of dopants, alloying between different materials, vertical stacking, and the presence of gases. Through materials engineering it is feasible to study the electrical properties of two-dimensional materials which are directly related to their crystalline structure, first Brillouin zone, and dispersion energy, the latter estimated through the tight-binding model. A review of the electrical properties directly related to the crystalline structure of these materials is made in this article for the two-dimensional materials used in the design of gas sensors. It was found that most 2D sensing materials have a hexagonal crystalline structure, although some materials have monoclinic, orthorhombic and triclinic structures. Through the simulation of the mathematical models of the dispersion energy, two-dimensional and three-dimensional electronic band structures were predicted for graphene, hexagonal boron nitride (h-BN) and silicene, which must be known before designing a gas sensor.

The design of nanometric electronic devices requires novel materials for improving their electrical performance from stages of design until their fabrication. Until now, several DC electrical conductivity models for composite materials have been proposed. However, these models must be valued to identify main design parameters that more efficiently control the electrical properties of the materials to be developed. In this paper, four different models used for modeling DC electrical conductivity of carbon nanotube-polymer composites are studied with the aim of obtaining a complete list of design parameters that allow guarantying to the designer an increase in electrical properties of the composite by means of carbon nanotubes.

No abstract

This article presents the design and implementation of a micropositioning system actuated by three piezoelectric stacks to control its displacements on XYZ axes. The use of conventional piezoelectric buzzers allows us to reduce fabrication costs. The working or mobile platform is the base for objects that will be manipulated, for example, in automated assembling. The micropositioner can be integrated into a microgripper to generate a complete manipulation system. For micropositioner fabrication, at first, Polylactic Acid (PLA) was chosen as the structural material, but after simulation and some experimental tests performed with a micropositioner made of Acrylonitrile Butadiene Styrene (ABS), it showed larger displacement (approx. 20%) due to its lower stiffness. A third test was performed with a positioner made with Polyethylene Terephthalate Glycol (PETG), obtaining an intermediate performance. The originality of this work resides in the geometrical arrangement based on thermoplastic polymer compliance mechanisms, as well as in the use of additive manufacturing to fabricate it. An experimental setup was developed to carry out experimental tests. ANSYS™ was used for simulation.

No abstract