Electrospun (K,Na)NbO${}_3$ piezoceramic fibers for self-powered tactile sensing application

This study investigates the electrical properties of electrospun ceramic fiber mats based on potassium sodium niobate ((K,Na)NbO${}_3$;KNN) for potential applications in soft-robotic tactile sensors. The rheological studies of electrospinning solutions exhibit shear thinning behavior, with a viscosity plateau between shear rates of 1-100 s${}^{-1}$. The thermal decomposition behavior of the KNN samples is analyzed using thermogravimetric analysis; the samples show multistep decomposition processes leading into a phase pure perovskite structure. For the electrospun KNN fiber mats, the electrical characterization reveals ferroelectric hysteresis loops with a high leakage current of ≈270 nA at 20 kV cm${}^{-1}$ and switching current behavior. The ferroelectric results indicate that a full polarization of KNN-fiber mats is not possible due to their electrical breakdown at high electrical fields. The integration of KNN short fibers into a soft-bending actuator demonstrates successful tactile sensing capabilities. The experimental findings reported here highlight the potential of electrospun KNN fiber mats for flexible and autonomous device applications in soft robotics. (© 2023 Wiley‐VCH GmbH)