Graphene sensing meshes for densely distributed strain field monitoring

Abstract

The objective of this study is to design and validate distributed strain field monitoring using a patterned nanocomposite “sensing mesh” that is coupled with an electrical impedance tomography (EIT) measurement strategy and algorithm. Although EIT has been used in other studies and in conjunction with a piezoresistive thin film for spatial damage detection, different strain components cannot be directly extracted from reconstructed EIT conductivity maps. Therefore, this study seeks to address this issue by patterning piezoresistive graphene-based thin films to form a mesh-like pattern. The high aspect ratio of each nanocomposite grid interconnect acts as a linear distributed strain sensor, capable of resolving strains along the entire length and direction of the element. This study first began with the design, fabrication, and characterization of the strain sensing response of a graphene-based thin film of high strain sensitivity. Second, the strain-sensitive film was spray-coated onto patterned polymer substrates to form the sensing meshes, which were then subjected to load tests. Upon validating distributed strain field monitoring through EIT, its applicability for field implementation and damage characterization was also demonstrated by instrumenting sensing meshes in the column of a seven-story reinforced-concrete building subjected to shaking table earthquake excitations. The large-scale shaking table test results successfully validated distributed damage detection.

Graphite-polydimethylsiloxane composite strain sensors for in-situ structural health monitoring

“…The strain gauges used to monitor built infrastructures are large [7,8] and expensive devices [7][8][9] that are difficult to scale down and embed in construction materials. This is particularly true for strain sensors based on optical interference gratings [26].…”

“…Non-destructive evaluation methods [1,2] are sought to activate the self-healing of construction materials [3][4][5][6] to mitigate against material disaggregation, and assist maintenance and rescue efforts. The strain sensors currently used to monitor built infrastructures are however large [7,8] and expensive devices [7][8][9]. These are difficult to scale down to the level of the granular texture of concrete and to insert in building materials.…”

Mixed regularization for damage mapping in three-dimensional self-sensing composites via EIT

“…Additionally, Loh and colleagues produced piezoresistive meshes on which they monitored strains via EIT. 11,12 With regard to damage sensing via EIT, Nonn et al used EIT to detect and localize impact damage in continuous carbon fiber composites. 13 Cagáň and colleagues also applied EIT to continuous carbon fiber composites, 14,15 including some probability of detection (POD) assessment of EIT.…”

Distributed Strain Monitoring Using Nanocomposite Paint Sensing Meshes

“…Whereas strain magnitudes can be estimated, strain fields (i.e., magnitudes and directionalities) cannot be reconstructed using classical EIT. To address this limitation, a “sensing mesh” composed of directional elements by patterning a nanocomposite coating was developed [ 23 ]. This approach was to configure the nanocomposite coating to form a grid-like pattern so that the strain magnitude along each directional element can be reconstructed from EIT, while their directions were based on the longitudinal axes of the grid’s struts.…”