Nonlinear Actuation of Casimir Oscillators toward Chaos: Comparison of Topological Insulators and Metals

Abstract

In the current study, we explore the sensitivity of the actuation dynamics of electromechanical systems on novel materials, e.g., Bi2Se3, which is a well-known 3D Topological Insulator (TI), and compare their response to metallic conductors, e.g., Au, that are currently used in devices. Bifurcation and phase portraits analysis in conservative systems suggest that the strong difference between the conduction states of Bi2Se3 and Au yields sufficiently weaker Casimir force to enhance stable operation. Furthermore, for nonconservative driven systems, the Melnikov function and Poincare portrait analysis probed the occurrence of chaotic behavior leading to increased risk for stiction. It was found that the presence of the TI enhanced stable operation against chaotic behavior over a significantly wider range of operation conditions in comparison to typical metallic conductors. Therefore, the use of TIs can allow sufficient surface conductance to apply electrostatic compensation of residual contact potentials and, at the same time, to yield sufficiently weak Casimir forces favoring long-term stable actuation dynamics against chaotic behavior.

Sensitivity of actuation dynamics on normal and lateral Casimir forces: Interaction of phase change and topological insulator materials

“…This theory describes the attractive interaction due to quantum fluctuations for all separations covering both the Casimir (longrange) and van der Waals (short-range) regimes. [1][2][3][4][5][6][7]13 The Casimir force is strongly dependent on the geometry and optical properties of the system, [14][15][16][17][18][19][20][21][22][23][24] thermal effects, [25][26][27][28] and the presence of corrugated boundaries between interacting bodies. 3,19,29,30 The latter point enables the feasibility to tailor the direction and strength of the Casimir force and consequently drive the actuation dynamic of NEMS/MEMS.…”

“…In fact, reducing the size of these devices could lead to chaotic motion that causes an abrupt change in the dynamical behavior of the system leading to stiction between actuating components. 21,22,24,32 The threshold condition for this phenomenon and its sensitivity on material optical properties are different for both the normal and lateral directions of motion. 21,29 So far, several studies have been performed to investigate the normal Casimir force for normal displacements and the lateral Casimir force by creating tangential displacement in devices.…”

“…21,29 So far, several studies have been performed to investigate the normal Casimir force for normal displacements and the lateral Casimir force by creating tangential displacement in devices. [5][6][7]21,22,24 The dependence of both the normal and lateral components of the Casimir force on optical properties and thermal effects and consequently their influence on the dynamical behavior of actuating devices can be diverse. 21,29 However, there is limited knowledge on how changes of the normal Casimir force by making lateral displacement in devices with corrugated surfaces will affect the dynamical actuation of devices and the occurrence of any associated chaotic motion.…”