Tailoring sensing behavior of Cu@multi-wall carbon nanotubes/polydimethylsiloxane strain sensors through surface Cu geometrical structures

Abstract

Strain sensing ability under various service conditions is a fundamental requirement of a strain sensor, while a structural design is a key for obtaining various sensing behaviors to realize high performance of the strain sensor. In this study, we report a new simplified fabrication strategy to produce excellent strain sensors made from copper@multi-wall carbon nanotubes/polydimethylsiloxane hybrid films by tailoring the surface Cu geometrical structures with different sensing functions. The Cu film was electrodeposited on the multi-wall carbon nanotubes/polydimethylsiloxane film substrates subjected to three different pre-strains of 10%, 20% and 30%. Thus, three types of sensors with different functionalities were fabricated accordingly. The 10% pre-strain sensor with a surface wrinkled Cu structure exhibited a broad strain range (up to 82%), an ultra-high sensitivity with a gauge factor of 263 at a strain of 10% and 2387 at a strain of 80%, and excellent cyclic stability up to 2 × 10³ cycles, which are promising to be applied in wearable flexible electronics and intelligent robots. However, the 30% pre-strain sensor with a curled Cu structure exhibited a strong linearity with a correlation coefficient of 99.3% in the whole strain range, which is expected to be used for structural health monitoring and weighing systems.