Memristor is an emerging fourth fundamental electronic element that can reduce the complexity of memory-wall architecture in the existing system. Therefore, this area demands lots of focus on material, material growth, and the process engineering domains. Here, we report a memristor using Cu2O1–x/CuO1–y heterojunctions, which is different from the conventional devices in notable ways. First, the mechanism is not filamentary. Second, the underlying mechanism is Cu vacancy migration, and the SET voltage scales with an electric field in the active layer. We use chemical vapor deposition (CVD) to deposit the Cu2O1–x and CuO1–y layers, making the process scalable over large areas. CVD also enables precise morphology and grain structure control, crucial for achieving memristive characteristics. The best devices have a SET/RESET voltage of ∼1.1 V, an endurance of more than 100 cycles, and a retention of more than 10,000 s.

The widely distributed reciprocating compressors contain abundant vibrational energy, and it is valuable to effectively harvest the mechanical vibration energy. However, the traditional vibration energy harvesters have shortages of a single harvesting direction and insufficient output under weak vibration excitation. Here, a two degrees of freedom in two directions structure triboelectric nanogenerator (TFTD-TENG) was proposed. TFTD-TENG can efficiently harvest the vertical and horizontal or composite directions vibration energy, and the additional solar cell (SC) on the TFTD-TENG can harvest static solar energy. To clarify its working principle, the kinematic characteristics and the mechanical models of the TFTD-TENG in horizontal and vertical directions were analyzed. Moreover, the main structural parameters were optimized. The vertical and horizontal output performance of the TFTD-TENG at vibration frequencies of 1–25 Hz and vibration amplitudes of 1–3 mm were comprehensively tested. For the composite vibration direction, a vibration direction recognition method based on the output voltage ratio was proposed. When the TFTD-TENG was installed on an air compressor, the output voltage of the vertical TENG was 192 V and the short-circuit current (Isc) was 8 μA, the output voltage of the horizontal TENG was 83 V and the Isc was 5 μA. And when the TENG units in two directions output in parallel, the TFTD-TENG can generate a maximum power of 1361.25 μW, matching a resistance value of 20 MΩ. The proposed TFTD-TENG shows excellent performance in vibration energy harvesting and self-powered sensing, which has great prospects in smart factories and artificial intelligence of things.

Thin-film-based energy storage devices, especially supercapacitors, are in high demand due to their high power density and ease of integration with portable electronic devices. However, their stability as well as performance is limited due to their substrate properties. Here we have fabricated halide perovskite-based flexible asymmetric supercapacitors by introducing quasi-solid-state gel electrolytes between two electrodes. We have studied the performance and stability of the supercapacitor fabricated on 50-and 200-μm-thick stainless-steel (SS) and 100-μm-thick flexible graphite substrates. A device fabricated on a thin SS substrate follows exponential decay-type behavior, while it is asymptotic for a flexible graphite substrate at a higher bending angle. Both devices are stable for a small twisting angle; however, the device performance decreases sharply for the SS substrate after 60° twisting angle due to fast delamination and crack formation. Bending and twisting cycle measurement of the supercapacitor on a flexible graphite substrate shows better cyclic stability over 50-μm-thick SS substrates due to dissipation of microstrain. To improve the operating voltage of the storage devices, stacked supercapacitors are designed with two or more subcells that can drive white light-emitting diodes (>3.0 V).

Poly(vinylidene fluoride) (PVDF) and its copolymers are useful for a diverse range of applications in energy production and storage, sensors, actuators, separator, and filter membranes. Herein, we report on the single-step transformation of electroactive tribo-negative pristine PVDF into tribo-positive PVDF copolymer (G-PVDF) by grafting poly(diethylene glycol methyl ether methacrylate) on the backbone by a coupled atom-transfer radical polymerization protocol. The resultant G-PVDF with rough spherulitic morphology is utilized to fabricate a triboelectric nanogenerator (G-TENG) using the combination of tribo-negative polydimethylsiloxane as active materials. Highly robust G-TENG generates a peak-to-peak voltage of ∼1050 V under open-circuit condition and an output current density of 31.25 × 10–2 A m–2 equivalent to an output power density of 56.25 W m–2. Furthermore, the application of the G-TENG as a realistic portable electrical power source is shown by powering over 400 market-available red light-emitting diodes and liquid crystal displays. The G-TENG shows mechanical stability over 9500 cycles and ambient stability over 150 days. Parallel to the scavenging of electrical energy from mechanical energy, we demonstrate the use of G-TENG for flexible self-powered health care applications. The synthesis of tribo-positive G-PVDF copolymer as a green energy-harvesting material has great potential for a variety of applications considering the versatile use of pristine PVDF.

In this study, Ag2BaSnS4 (SBTS) nanostructures with tunable compositions are synthesized by using a simple and environmentally benign solvothermal method. X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDX), photoluminescence (PL), and ultraviolet–visible spectroscopy (UV–vis) are used to examine the sample’s physicochemical properties. To further demonstrate the electrochemical efficiency of the manufactured nanoparticles for energy production and storage, a systematic analysis is also performed. The Ag2BaSnS4 (SBTS) electrode shows the best performance for the supercapacitor electrode based on the results of the galvanostatic charge–discharge (GCD), cyclic voltammetry (CV), and stability tests, with an excellent energy density of 49.86 W h kg–1, a specific capacitance of 1438.43 F g–1, and power density with an average value of 0.00062 W kg–1, and 95% of the charge storage capability is maintained upon 2000 cycles. When it comes to catalyzing the hydrogen evolution reaction (HER), the SBTS electrode shows substantial improvement at just slightly elevated potentials of about 60 mV. When catalyzing the oxygen evolution reaction (OER), the SBTS electrode shows a Tafel slope of 70 mV dec–1 at a current density of 10 mA cm2, suggesting a fast and efficient process. These findings suggest that SBTS nanostructures might be used as high-performance electrode materials in various supercapacitors and water-splitting devices.

Through-silicon via (TSV) technology is used to produce a TiO2 gas sensor. The conical TSV structure is constructed using a laser with a wavelength of 1064 nm, and the depth-to-diameter ratio is 20:13 (200 μm: 130 μm). The sensing layer TiO2 is fabricated by using a thermal oxidation (TO) process and covers the TSV structure. X-ray diffraction and energy-dispersive X-ray spectroscopy analysis show that the main plane of the TiO2 film is (110), and there is a uniformly covered TSV structure. For the TiO2 gas sensor operating at room temperature (RT) of 25 °C, the recorded sensor responses are 12.08, 15, 18.5, 23.9, 31, and 38.9%, corresponding to NO2 concentrations of 0.25, 0.5, 1, 2, 5, and 10 ppm. In assessing the stability, the sensing result registers 18.5% over three cycles at 1 ppm of NO2, with a deviation under ±0.2%. The TiO2 material exhibits better selectivity for NO2 than for other gases (NH3, CO2, CO, H2, H2S, and SO2). The results of this study show that the RT TiO2 gas sensor with a TSV structure is stable, reversible, and exhibits good selectivity for NO2 gas.

In the era of the Internet of Things (IoT), the development of an intelligent sensor system with a sustainable power supply, convenient deployment, and versatile use has emerged as an urgent challenge. Triboelectric nanogenerators (TENGs) stand out as some of the most promising energy solutions in this context. They possess the capability of directly transforming mechanical stimuli into electrical signals, making them highly valuable for self-powered sensor applications. Sensors based on a TENG exhibit the advantages of uncomplicated structures and remarkable instantaneous power density, thereby serving as a critical component in the construction of intelligent sensor systems. In parallel, machine learning (ML), with its attributes of cost-effectiveness, short development cycles, and robust data processing and predictive capabilities, has matured over more than five decades to meet the research requirements of various disciplines. ML demonstrates exceptional prowess in managing the substantial volume of electrical signals generated by a TENG. This paper presents a comprehensive overview of recent advancements in signal processing and intelligent identification within sensor systems based on a TENG. The technical characteristics and research status of this convergence are explored across five key domains: traffic safety, environmental monitoring, information security, motion tracking, and human–computer interaction. Finally, this paper delves into the current challenges and future development trends within this field, offering an analytical perspective on how to enhance its prospects and ultimately opening up a broader landscape for potential applications. We believe that the fusion of ML technology and TENG sensors will catalyze the rapid evolution of intelligent sensor networks in the foreseeable future, providing valuable insights for other research domains as well.

Nowadays, flexible magnetoelectric (ME) heterostructures comprising lead-free piezoelectrics are of considerable interest for commercializing wearable electronic devices such as energy harvesters, nonvolatile memory, implantable medical diagnostics, and sensors. Here, we fabricate a highly flexible, cost-effective, nanostructured magnetic field sensor comprising an AlN/Ni–Mn–In ME heterostructure over Ni foils. The functionality of the AlN/Ni–Mn–In/Ni heterostructure has been investigated by measuring the magnetodielectric MD (%) and magnetoelectric coupling (αME) coefficient with Ni–Mn–In thickness, anisotropy, and flexibility. The thickness ratio of piezoelectric AlN (∼400 nm) and magnetostrictive Ni–Mn–In (∼385 nm) layers has been optimized to achieve the high performance of the magnetic sensor. The encapsulation of the Ni–Mn–In layer drastically enhances the performance of the fabricated heterostructure. The highest MD ∼ 2.95% and αME ∼ 3.2 V/cm·Oe have been recorded with an equal thickness ratio of AlN and Ni–Mn–In layers. It could be ascribed to the large magnetostrictive strain transferred to the AlN piezoelectric layer, which enhances the induced ME voltage. Moreover, the nonzero value of αME at zero bias magnetic field has been observed and related to the piezomagnetic coefficient (q) grading in the Ni–Mn–In(+q)/Ni(−q) ferromagnetic system, which enhances the strength of magnetoelectric coupling. The fabricated device has easily detected the ultralow magnetic field of up to or less than ∼1 μT. In addition, the anisotropic functionality of the device has been explained by measuring the magnetodielectric and magnetoelectric characteristics in parallel and perpendicular dc bias fields. The MD and ME characteristics remain stable up to 2500 bending cycles. Hence, the present lead-free ME heterostructure integrated over a flexible Ni foil can enhance the multifunctionality of futuristic flexible magnetic field sensors for room-temperature applications.

In this work, we demonstrate that the HTI (HTI = histammonium iodide) dication was incorporated into the PbI2 precursor solution to induce the preferred vertical orientation of the 2D Dion–Jacobson (DJ) perovskite film using a two-step deposition. 2D DJ (HTI) (FA)x(MA)1–xPbnI3n+1 (FA = formamidinium, MA = methylammonium) films show a significantly improved film quality with enlarged grain sizes and vertical orientation to the substrate. Moreover, perovskite films prepared from the HTI embedded PbI2 layer also exhibit greatly reduced film decomposition from oxygen and humidity in ambient air conditions. As a result, the champion device shows a high power conversion efficiency (PCE) of 13.06%, in contrast to 7.98% for the 3D (FA)x(MA)1–xPbI3 perovskite device without HTI dication. The 2D DJ (HTI) (FA)x(MA)1–xPbnI3n+1 devices show enhanced stability, maintaining 72% of their initial PCE after 2000 h in ambient air conditions (relative humidity 35–50%). However, the 3D (FA)x(MA)1–xPbI3 perovskite device dropped to 24% of its PCE within 2000 h. Our results suggest that the precursor engineering containing 2D perovskite organic spacer in a two-step process is a potential approach toward further improving the PCE and stability of the 2D DJ perovskite solar cell.

Piezoelectric materials are used to fabricate acoustic transducers for bubble chambers in search for particles of dark matter. It has been shown that bubbles initiated by nuclear recoils emit acoustic radiation distinguishable from the phase transitions caused by alpha-decay─the main background noise in such searches. However, these piezoelectric materials must exhibit ultralow radioactivity to minimize the neutron background for dark matter detection while possessing high acoustic sensitivity. Here, for the first time, we demonstrate radiopure high-performance piezoelectric ceramics meeting the criteria for acoustic sensing. The screening of radiopure precursors is performed to identify those with low 238U, 232Th, and 210Pb contents. Using the radiopure precursors, piezoelectric ceramics with varying compositions are synthesized, and their electromechanical acoustic sensing performance is evaluated. Multiple synthesis modifications such as doping and texturing are utilized to tailor the piezoelectric coefficients of the piezoelectric ceramics, and the relationship between the piezoelectric coefficients and acoustic sensing performance of the ceramics is investigated. Acoustic transducers fabricated using textured Pb(Mg1/3Nb2/3)O3–PbTiO3 (PMN–PT) ceramics are found to exhibit superior acoustic sensitivity due to their high piezoelectric transduction coefficient (d33 × g33). This study demonstrates a useful figure of merit (FOM) for acoustic sensing in bubble chambers.