High β-Phase Barium Titanium Oxide Nanoparticle/P(VDF-TrFE) Composites for Mechanical Sensing

The progress in sensing technology has driven the research toward hybrid transduction for effective and multidimensional applications. The introduction of hybrid nanocomposites provides the necessary cutting-edge progression for an advanced class of sensors. On this pretext, an extensive study on the piezoelectric/triboelectric transduction properties of barium titanate (BTO)-doped poly(vinylidene fluoride–trifluoroethylene) (P(VDF-TrFE)) nanocomposites is presented in detail. In this work, the pristine P(VDF-TrFE) and BTO mixed with P(VDF-TrFE) nanocomposite thin film was prepared by varying the %weight ratio for the high β phase to show better piezoelectricity. Furthermore, a biomechanical sensor with a dual transduction mechanism is fabricated by using the optimized nanocomposite thin film. This work aims to report the effect of the %weight ratio of BTO in P(VDF-TrFE) by optimizing the development of pristine P(VDF-TrFE) and analyzing its dual transduction properties. A 15% weight ratio of BTO in 20% P(VDF-TrFE) nanocomposite film shows the highest piezoelectric coefficient of 0.58 nm/V. The addition of BTO into 20% P(VDF-TrFE) shows considerable improvement over pristine P(VDF-TrFE) films (≃9 times). Furthermore, a triboelectric shift is observed from a tribonegative to a tribopositive nanocomposite after the addition of BTO in 20% P(VDF-TrFE). The surface potential shifts from −382.5 to 495 mV in 20% P(VDF-TrFE) and 15% BTO/20% P(VDF-TrFE). The charge retention metric ΔV200 also decreases from 150 to 60 mV in 20% P(VDF-TrFE) and 15% BTO/20% P(VDF-TrFE), indicating the improvement in charge retention in 15% BTO/20% P(VDF-TrFE). Finally, the fabricated dual transduction biomechanical sensor demonstrates a sensing range of 1–60 kPa with a minimal hysteresis range of ≃4.6 to 7.2% and an average sensitivity of ≃21 mV·kPa–1 over a frequency range of 1–4 Hz with a maximum sensitivity of 27 mV·kPa–1 at 4 Hz for the triboelectric output. Furthermore, the sensor also shows a hysteresis of ≃3.6 to 6.1% and an average sensitivity of 9.2 mV·kPa–1 over a frequency range of 1–4 Hz with a maximum sensitivity of 14.1 mV·kPa–1 at 4 Hz for the piezoelectric output. The dual transduction enables an accurate differentiation of touch responses and also has potential application in biomechanical sensing such as pressure, force, and acceleration detection.