(K,Na)NbO₃ Nanofiber-based Self-Powered Sensors for Accurate Detection of Dynamic Strain

Abstract

A self-powered active strain sensor based on well-aligned (K,Na)NbO3 piezoelectric nanofibers is successfully fabricated through the electrospinning and polymer packaging process. The device exhibits a fast, active response to dynamic strain by generating impulsive voltage signal that is dependent on the amplitude of the dynamic strains and the vibration frequency. When the frequency is fixed at 1 Hz, the peak to peak value of the voltage increases from ∼1 to ∼40 mV, and the strain changes from 1 to 6%. Furthermore, the output voltage is linearly increased by an order of magnitude with the frequency changing from 0.2 to 5 Hz under the same strain amplitude. The influence of frequency on the output voltage can be further enhanced at higher strain amplitude. This phenomenon is attributed to the increased generating rate of piezoelectric charges under higher strain rate of the nanofibers. By counting the pulse separation of the voltage peaks, the vibration frequency is synchronously measured during the sensing process. The accuracy of the sensing results can be improved by calibration according to the frequency-dependent sensing behavior.

Orientation-dependent piezoresponse and high-performance energy harvesting of lead-free (K,Na)NbO3 nanorod arrays

“…7(d), the VING with KNN NRAs could generate impulsive output voltage with maximum amplitude up to 10 V, which was much higher than the reported value of KNN NRAs in the literatures. 22,[24][25][26]29 Meanwhile, the peak value of shortcircuit current generated by the VING was $50 nA, which is shown in Fig. 7(e).…”

“…For example, although the NGs based on KNN-based nanobers could generate a voltage output with amplitude up to 1.5 V, this is not high enough to drive many low-power-consumption micro-devices such as a LED. 24 That effect might be attributed to a loosened polycrystalline structure, limiting the piezoelectric response of the nanobers. As is well-known, the piezoelectric constants for piezoelectric single-crystals are always much higher than for poly-crystals.…”

Sensitivity enhancement of the tactile sensor based on hydrothermally grown ZnO nanorods modified by catalytic Au nanoparticles

“…Afterwards, a positive voltage pulse signal is generated by the sensor instantly when the pressure is released. This phenomenon should be attributed to the incomplete releasing of ZnO NRs due to the rebounding of the PDMS material, resulting in a continued increase in the output voltage after the finger is lifted and detached from the top surface of the PDMS [32]. During the process of pressing and releasing, the sensor is capable to convert the external force into electric signals.…”

Synthesis and characterization of two-dimensional lead-free (K, Na)NbO3 micro/nano piezoelectric structures

“…Driven by an increasing demand for the textured ceramics and the flexible piezoelectric generators, the research on low dimensional lead-free niobate based micro/nano-structures have made great progress [16][17][18]. For instance, the well-textured KNN ceramics are considered to possess high piezoelectric response [9,19].…”