Electrospun bundled carbon nanofibers for skin-inspired tactile sensing,proprioception and gesture tracking applications

In this work,we report a class of wearable,stitchable,and sensitive carbon nanofiber(CNF)-polydimethylsiloxane(PDMS)composite-based piezoresistive sensors realized by carbonizing electrospun polyacrylonitrile(PAN)nanofibers and subsequently embedding in PDMS elastomeric thin films.Electro-mechanical tactile sensing characterization of the resulting piezoresistive strain sensors revealed a linear response with an average force sensitivity of~1.82 kN−1 for normal forces up to 20 N.The real-time functionality of the CNF-PDMS composite sensors in wearable body sensor networks and advanced bionic skin applications was demonstrated through human motion and gesture monitoring experiments.A skin-inspired artificial soft sensor capable of demonstrating proprioceptive and tactile sensory perception utilizing CNF bundles has been shown.Furthermore,a 16-point pressure-sensitive flexible sensor array mimicking slow adapting low threshold mechanoreceptors of glabrous skin was demonstrated.Such devices in tandem with neuromorphic circuits can potentially recreate the sense of touch in robotic arms and restore somatosensory perception in amputees.

Single and bundled carbon nanofibers as ultralightweight and flexible piezoresistive sensors

This work demonstrates the application of electrospun single and bundled carbon nanofibers(CNFs)as piezoresistive sensing elements in flexible and ultralightweight sensors.Material,electrical,and nanomechanical characterizations were conducted on the CNFs to understand the effect of the critical synthesis parameter—the pyrolyzation temperature on the morphological,structural,and electrical properties.The mechanism of conductive path change under the influence of external stress was hypothesized to explain the piezoresistive behavior observed in the CNF bundles.Quasi-static tensile strain characterization of the CNF bundle-based flexible strain sensor showed a linear response with an average gauge factor of 11.14(for tensile strains up to 50%).Furthermore,conductive graphitic domain discontinuity model was invoked to explain the piezoresistivity originating in a single isolated electrospun CNF.Finally,a single piezoresistive CNF was utilized as a sensing element in an NEMS flow sensor to demonstrate air flow sensing in the range of 5-35 m/s.