Optimization of the sensing performance of BaTiO3/P(VDF-TrFE) via proton irradiation

Abstract

A pyroelectric–piezoelectric dual-mode sensor simultaneously decodes temperature and strain, serving as a core component for health monitoring, human–machine interfaces, and bionic skin applications. To achieve high fidelity, self-powering, and long-term endurance, the sensing materials must balance sensitivity, stability, and multi-physics field coordination across multiple scales. This study employs a synergistic strategy combining a barium titanate (BaTiO₃) composite with proton irradiation to regulate a polyvinylidene fluoride-trifluoroethylene (P(VDF-TrFE)) copolymer. By enhancing the crystallinity and the β-phase content of P(VDF-TrFE) while introducing oxygen vacancies and lattice distortions within the BaTiO₃ lattice, the strategy significantly strengthens interfacial polarization coupling and charge transport efficiency. As a result, a composite with 2 wt% BaTiO₃ shows an increased pyroelectric coefficient (p) of 66.1 µC m⁻² K⁻¹. Although the piezoelectric coefficient (d₃₃) slightly decreases from 22.0 pC N⁻¹ to 20.1 pC N⁻¹, its variation range (standard deviation) narrows from 3.9 to 3.1. Subsequent proton irradiation at 1 × 10¹⁰ p cm⁻² further increases p to 86.6 µC m⁻² K⁻¹, accompanied by a slight decrease in d₃₃. At 5 × 10¹⁰ p cm⁻² fluence, p maintains a 6.8% increase compared to pre-irradiation levels, and d₃₃ recovers to 20.0 pC N⁻¹ with a standard deviation reduced to 2.4, effectively balancing piezoelectric uniformity and stability with high pyroelectric sensitivity. The composite film exhibits a linear sensitivity of 1.2 V K⁻¹ over the temperature range of 0.1–12.2 K, with no degradation observed after 10³ thermal cycles. It conformally adheres to the human body and enables real-time analysis of respiration, pulse, and touch signals, offering a novel approach for high-sensitivity, high-reliability dual-mode sensing in wearable electronics and bionic skin applications.