Flexible
strain sensors have recently attracted great attention
due to their promising applications in human motion detection, healthcare
monitoring, human–machine interfaces, and so forth. However,
traditional uniaxial strain sensors can only detect strain in a single
direction. Herein, an anisotropic flexible strain sensor is fabricated
based on conductive and highly aligned cellulose composite nanofibers,
via facile electrospinning cellulose acetate, deacetylation, and in
situ polymerization of pyrrole, to detect complex multidimensional
strains. Benefiting from the unique well-ordered structure of conductive
composite nanofibers, the obtained strain sensor shows extraordinary
anisotropic sensing performance with a sensitivity of 0.73 and 0.01
for the tensile applied perpendicular and parallel to the nanofiber
alignment, respectively. The sensor also exhibits outstanding durability
(2000 cycles) due to the strong hydrogen bonding between cellulose
nanofibers and polypyrrole. Moreover, the flexible strain sensors
exhibit promising potentials for application in motion detection,
as demonstrated by the detection of various joint movements in the
human body.