Flexible piezoelectric nanogenerators are emerging as a promising solution for powering next-generation flexible electronics by converting mechanical energy into electrical energy. However, traditional ferroelectric ceramics, despite their excellent piezoelectric properties, lack flexibility; while piezoelectric polymers, although highly flexible, have low piezoelectricity. The quest to develop materials that combine high piezoelectricity with exceptional flexibility has thus become a research focus. Herein, we present a breakthrough in this field with the fabrication of freestanding (111)-oriented PbZr_0.52Ti_0.48O₃ single crystalline thin films, which exhibit remarkable flexibility and a high converse piezoelectric coefficient (~585 pm/V). This is achieved through water-soluble sacrificial layer to relieve substrate clamping and controlling the crystal orientation to further enhance the piezoelectric response. Our nanogenerators, constructed using these freestanding nanoscale membranes, demonstrate a record-high output power density (~63.5 mW/cm³), excellent flexibility (with a strain tolerance >3.4%), and superior mechanical stability in cycling tests (>60,000 cycles). These advancements pave the way for high-performance, flexible electronic devices utilizing ferroelectric oxide thin films.

Printing technology has revolutionized manufacturing by enabling high-volume, multipurpose, low-cost production with minimal environmental impact. This advancement has led to the integration of flexible electronic devices, such as displays, actuators, and sensors, into various consumer markets. Over the past few decades, printed electronics have garnered significant interest from both academic and industrial communities. Among these, flexible strain sensors stand out due to their adaptability and potential for large-scale applications. However, a comprehensive analysis of their sensing performance, particularly with respect to printability, remains lacking. This review aims to systematically explore the development of flexible strain sensors produced through printing technology, focusing on key aspects such as the formulation of conductive inks, the use of diverse substrate materials, and the challenges associated with printability. Additionally, it delves into the practical applications of these sensors across multiple industries. By providing an in-depth examination of these factors, this review offers valuable insights into the current state of printed electronics and highlights their future potential in advancing flexible sensing technologies.

With the prosperous development of wearable electronics, flexible radio-frequency wireless antenna sensors have attracted considerable interest due to their various applications in the Internet of things (IoT).

Memristors have been intensively studied in recent years as promising building blocks for next-generation nonvolatile memory, artificial neural networks and brain-inspired computing systems. However, most memristors cannot simultaneously function in extremely low and high temperatures, limiting their use for many harsh environment applications. Here, we demonstrate that the memristors based on high-Curie temperature ferroelectrics can resolve these issues. Excellent synaptic learning and memory functions can be achieved in BiFeO ₃ (BFO)-based ferroelectric memristors in an ultra-wide temperature range. Correlation between electronic transport and ferroelectric properties is established by the coincidence of resistance and ferroelectricity switch and the direct visualization of local current and domain distributions. The interfacial barrier modification by the reversal of ferroelectric polarization leads to a robust resistance switching behavior. Various synaptic functions including long-term potentiation/depression, consecutive potentiation/depression and spike-timing dependent plasticity have been realized in the BFO ferroelectric memristors over an extremely wide temperature range of −170 °C ∼ 300 °C, which even can be extended to 500 °C due to the robust ferroelectricity of BFO at high temperatures. Our findings illustrate that the BFO ferroelectric memristors are promising candidates for ultra-wide temperature electronic synapse in extreme or harsh environments.

As an emerging phenomenon in oxide heterostructures, the ferroelectric control of electronic transport is attracting considerable research attention. However, the effect of ferroelectric polarization on resistive switching (RS) remains controversial. In this study, to determine the effects of ferroelectric polarization on memory characteristics, ferroelectric and non-ferroelectric BaTiO₃ (BTO) films were fabricated using different oxygen partial pressures (Po₂) during film growth. A correlated electron oxide, SmNiO₃ (SNO), was selected as the bottom electrode. Based on piezoelectric force microscopy, ferroelectricity was verified in the BTO films prepared at Po₂ ≥ 3 Pa, whereas the films fabricated at lower Po₂ did not exhibit ferroelectricity. Remarkable RS with an ON/OFF ratio of 10⁴% was clearly observed in heterostructures containing ferroelectric BTO, while RS was negligible in structures with non-ferroelectric BTO. The strong ferroelectricity dependence of RS behavior on the BTO/SNO heterostructures was attributed to the ferroelectric control of device transport between bulk-limited current in the low-resistance state and interface-limited conductance in the high-resistance state, which results from the modulation of the potential barrier at the BTO/SNO interface. The findings provide strong evidence for the dominant effect of ferroelectric polarization of BTO on the transport properties of BTO/SNO heterostructures.