Molecularly Thin Polyaramid Nanomechanical Resonators

TL;DR

This paper reports the creation and characterization of the first nanomechanical resonators from two-dimensional polyaramid nanosheets, demonstrating their potential for molecular-scale NEMS with high strength and low density.

Contribution

It introduces the fabrication and mechanical analysis of 2D polyaramid nanomechanical resonators, a novel class of molecular-scale polymeric NEMS.

Findings

Resonators have thicknesses as small as 8 nm.

Eigenfrequencies match tensioned plate theory without residual gas.

Gas presence affects resonance due to bulging and slack.

Abstract

Two-dimensional polyaramids exhibit strong hydrogen bonding to create molecularly thin nanosheets analogous to graphene. Here, we report the first nanomechanical resonators made out of a two-dimensional polyaramid, 2DPA-1, with thicknesses as small as 8 nm. To fabricate these molecular-scale resonators, we transferred nanofilms of 2DPA-1 onto chips with previously etched arrays of circular microwells. We then characterized the thermal resonances of these resonators under different conditions. When there is no residual gas inside the 2DPA-1-covered microwells, the eigenfrequencies are well-described by a tensioned plate theory, providing the Young's modulus and tension of the 2DPA-1 nanofilms. With gas present, the nanofilms bulge up and mechanical resonances are modified due to the adhesion, bulging and slack present in the system. The fabrication and mechanical characterization of these first 2DPA-1 nanomechanical resonators represent a convincing path toward molecular-scale polymeric NEMS with high mechanical strength, low density, and synthetic processability.