# Converse flexoelectric two-dimensional MoS2 actuator

## TL;DR

Researchers developed a two-dimensional molybdenum disulfide actuator that shows strong converse flexoelectric performance, especially at the nanoscale.

## Contribution

The study introduces a novel two-dimensional MoS2-based actuator with significantly enhanced converse flexoelectric response at nanoscale thicknesses.

## Key findings

- The actuator achieves resonant displacements up to ~45 nm under 20 kHz AC excitation.
- Performance exceeds existing flexoelectric actuators by over an order of magnitude when normalized by thickness.
- The actuator maintains functionality under extreme conditions like vacuum and cryogenic temperatures.

## Abstract

Converse flexoelectric actuators offer significant potential for diverse applications due to their rapid response, resilience in extreme environments, and broad material compatibility. However, their development has been limited, primarily because flexoelectric effects are negligible in bulk materials. At the nanoscale, the converse flexoelectric effect becomes much more promising, as the electric field gradient scales quadratically with decreasing material thickness. Here, we report a converse flexoelectric actuator based on two-dimensional molybdenum disulfide. Under alternating current excitation near 20 kHz, the actuator exhibits resonant displacements up to ~45 nm, approximately two orders of magnitude larger than the thickness of the molybdenum disulfide active layer. This performance exceeds that of existing flexoelectric actuators by more than an order of magnitude when normalized by active layer thickness. Moreover, the actuator maintains strong flexoelectric responses under extreme conditions, including vacuum, cryogenic temperatures, and repeated cycling, highlighting the robustness and broad applicability of two-dimensional material-based converse flexoelectric systems.

Nanoscale thickness strongly enhances the converse flexoelectric effect, as the electric field gradient scales quadratically with decreasing thickness. This study demonstrates a two-dimensional material-based converse flexoelectric actuator.