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Dual‐layer nanotube‐based smart skin for enhanced noncontact strain sensing
Author(s) -
Sun Peng,
Bachilo Sergei M.,
Lin ChingWei,
Nagarajaiah Satish,
Weisman R. Bruce
Publication year - 2019
Publication title -
structural control and health monitoring
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.587
H-Index - 62
eISSN - 1545-2263
pISSN - 1545-2255
DOI - 10.1002/stc.2279
Subject(s) - materials science , carbon nanotube , layer (electronics) , polymer substrate , strain (injury) , polymer , optoelectronics , composite material , substrate (aquarium) , nanotechnology , medicine , oceanography , geology
Summary The remarkable optical properties of single‐walled carbon nanotubes suggest their use as nanoscale strain sensors. To help implement this idea as a practical technology, we have devised a new dual‐layer strain‐sensing smart skin. A submicron thick sensing layer of dilute, individualized nanotubes in poly(9,9‐di‐n‐octylfluorenyl‐2,7‐diyl) (PFO) polymer is deposited onto the substrate to be monitored and then overcoated with a transparent protective polymer layer. Subsequent substrate strains are transmitted to the nanotubes, altering their semiconducting band gaps and causing systematic shifts in their characteristic emission spectra. These shifts are recorded by irradiating a point on the surface with a small laser and capturing the resulting nanotube emission with a short‐wave infrared spectrometer. We found that consistency of film strain readings is significantly improved by thermal annealing of the deposited sensing layer before top coat application. Performance tests on a poly(methyl methacrylate) (PMMA) test specimen subjected to cyclic tensile stress show good strain sensing over the range from 0 to 2000 μ ε . Further tests on a stressed copper plate demonstrate that this method can be used with point‐wise scanning to generate detailed two‐dimensional maps of accumulated strain. To our knowledge, such maps cannot be obtained using any other nonperturbing strain‐sensing method.