Graphene as a nanoelectromechanical reference piezoresistor

Abstract

Motivated by the recent prediction of anisotropy in piezoresistance of ballistic graphene along longitudinal and transverse directions, we investigate the angular gauge factor of graphene in the ballistic and diffusive regimes using highly efficient quantum transport models. It is shown that the angular gauge factor in both ballistic and diffusive graphene between 0 • to 90 • bears a sinusoidal relation with a periodicity of π due to the reduction of sixfold symmetry into a twofold symmetry as a result of applied strain. The angular gauge factor is zero at critical angles 20 • and 56 • in ballistic and diffusive regimes, respectively. Based on these findings, we propose a graphene-based ballistic nanosensor which can be used as a reference piezoresistor in a Wheatstone bridge readout technique. The reference sensors proposed here are unsusceptible to inherent residual strain present in strain sensors and unwanted strain generated by the vapors in explosives detection. The theoretical models developed in this paper can be applied to explore similar applications in other two-dimensional Dirac materials. The proposals made here potentially pave the way for implementation of nanoelectromechanical strain sensors based on the principle of ballistic transport, which will eventually replace conventional microelectromechanical piezoresistance sensors with a decrease in feature size. The presence of strain-insensitive "critical angle" in graphene may be useful in flexible wearable electronics also.

Ballistic graphene array for ultra-high pressure sensing

“…Despite a very low GF [10,12,13,33], graphene has a significantly higher PS per unit area than silicon (10 3 − 10 4 times) and GaAs (10 5 times) pressure sensors due to its high surface-to-volume ratio [10]. Hence, other atomically thin 2-D materials are also expected to have a high-PS like graphene or even more [11].…”

“…We measure the deflection of membrane as a function of pressure using membrane theory [25,26] and obtain the strain in the membrane. Using the values of strain as a function of pressure, we calculate the PS using the value of GF of graphene in different transport regimes [12,13]. Graphene has a very low GF across different transport regimes.…”

“…In order to calculate PS from uni-axial strain GF, strain along the direction of current flow is required. [12,13]. Thus, we obtain a mathematical expression of strain along a specific direction of the deflected membrane.…”

“…Usually, 2-D Dirac materials such as graphene have a lower gauge factor (GF) than non-Dirac 2-D materials such as layered transition metal dichalcogenides (TMDs), phosphorene, arsenene, and to name a few due to the presence of robust Dirac cones [12,13]. Hence, non-Dirac 2-D materials have higher PS than 2-D Dirac materials [11,[14][15][16][17][18][19].…”

The New Material Battery Based on Mg/C‐π

“…Graphene has a large surface area [26] and has π-orbitals [27] so that it can interact with metal nanoparticles, [28] and deposition of metal into the graphene structure with the aim of inhibiting and reducing the possibility of agglomeration between graphene sheets (nanospacer agents) so as to increase the active surface area, [29] electronic conductivity, and the ionic diffusion potential of graphene occurs. [30] Magnesium (Mg) has good thermal and electrical conductivity, low equivalent weight and density (1.74 g cm À3 ), [23] a low potential (-2.38 V), a hexagonal structure, is not easy to slip when interacting with other elements, nontoxic, [31] abundant (about 2.3% by weight of the Earth's crust) and widespread, cheap (%$1000/ton), and has a fairly high charge storage capacity (2205 mAh g À1 vs 3862 mAh g À1 for Li) and theoretical volumetric capacity (3833 mAh cm À3 vs 2046 mAh cm À3 for Li).…”