Novel Methodologies for Multiaxial Strain Measurements with Piezoresistive Films based on Graphene Nanoplatelets

Abstract

Many recent investigations in the context of graphene nanoplatelets (GNPs) coatings report surface strain measurements by using piezoresistive sensing capabilities. An often underestimated problem is that the strain field is unknown and the principal strain components as well as their orientations must be determined. Herein, GNP films subjected to multiaxial strain are examined. Experimental results show that although the sensitivity to longitudinal strain is the highest, the ratio between transverse and longitudinal sensitivity exceeds 0.5. The sensitivity to shear strain is much lower. A model assisted study of a random network provides additional guidelines for the different electromechanical sensitivities. In practice, the GNP film is usually subjected to different strains simultaneously so that the multiaxial strain measurement becomes difficult. Therefore, two novel approaches for sensing plane strain components with circular GNP films are developed and successfully verified in experiments. The numerical approach is called strain‐differential electrical impedance tomography (SD‐EIT), where the proposed piezoresistive model elementwise in a finite element model is implemented and the strain components of a strain rosette are reconstructed. Moreover, an analytical approach is derived from SD‐EIT and exhibits further the opportunity to detect anomalies within the piezoresistive sensing behavior of GNP films.

Highly Stretchable Photovoltaic Module with Improved Mechanical Robustness through Elastomeric Interconnections

“…FDTD Simulations: The von Mises stress and its distribution were simulated using the solid mechanics library in COMSOL Multiphysics software. [28] The linear model was applied to three different materials when strain is less than 10%: silicon, PDMS, and ECOFLEX. For hyperplastic stretching (10% or more) Neo-Hookean model was applied.…”

“…[24] However, while the stretchable module allows for elongation and deformability, the rigid devices in this structure might be more susceptible to unexpected deformations, like Poisson's effect. [26][27][28] Thus, addressing the vulnerability to unintended deformations is crucial to enhancing the overall robustness and usability of the stretchable module with a design-engineered platform. [23] DOI: 10.1002/solr.202300973 Stretchable photovoltaics have garnered increasing attention due to their adaptability to various surfaces and applications, meeting the rising demands for portable and flexible power sources.…”

“…[ 24 ] However, while the stretchable module allows for elongation and deformability, the rigid devices in this structure might be more susceptible to unexpected deformations, like Poisson's effect. [ 26–28 ] Thus, addressing the vulnerability to unintended deformations is crucial to enhancing the overall robustness and usability of the stretchable module with a design‐engineered platform. [ 23 ]…”