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Memristors are considered one of the most promising new-generation memory technologies due to their high integration density, fast read/write speeds, and ultra-low power consumption. Natural biomaterials have attracted interest in integrated circuits and electronics because of their environmental friendliness, sustainability, low cost, and excellent biocompatibility. In this study, a sustainable biomemristor with Ag/mugwort:PVDF/ITO structure was prepared using spin-coating and magnetron sputtering methods, which exhibited excellent durability, significant resistance switching (RS) behavior and unidirectional conduction properties when three metals were used as top electrode. By studying the conductivity mechanism of the device, a charge conduction model was established by the combination of F-N tunneling, redox, and complexation reaction. Finally, the novel logic gate circuits were constructed using the as-prepared memristor, and further memristor based encryption circuit using 3-8 decoder was innovatively designed, which can realize uniform rule encryption and decryption of medical information for data and medical images. Therefore, this work realizes the integration of memristor with traditional electronic technology and expands the applications of sustainable biomemristors in digital circuits, data encryption, and medical image security.

The memristor, characterized by its resistive switching (RS) behavior, has garnered significant interest within the scientific community, particularly because of its vast potential applications in the fields of artificial intelligence (AI) and information storage. This is attributed to its unique properties, which align well with the requirements of advanced computational and memory systems. Ferroelectric memristors are currently a thriving area of research, and this study uses Sm-doped Pb(Mg1/3Nb2/3)O3–PbTiO3 (Sm-PMN-PT) and polyvinylidene difluoride (PVDF) as the functional layer. A multi-factor responsive memristor based on a Ag/Sm-PMN-PT:PVDF/ITO sandwich structure is fabricated, for which the RS behavior of the memristor can be adjusted by multi-factors such as voltage scanning rate, bias voltage amplitude, temperature and environmental humidity. Specifically, this device is sensitive to changes in environmental humidity and exhibits the properties of an artificial neural synapse. These advantageous characteristics endow this device with great potential for use in environmental sensors and artificial neural network (ANN) systems.

Metasurface-based nanoprinting (meta-nanoprinting) has fully demonstrated its advantages in ultrahigh-density grayscale/color image recording and display. A typical meta-nanoprinting device usually has image resolutions reaching 80 k dots per inch (dpi), far exceeding conventional technology such as gravure printing (typ. 5 k dpi). Besides, by fully exploiting the design degrees of freedom of nanostructured metasurfaces, meta-nanoprinting has been developed from previous single-channel to multiple-channels, to current multifunctional integration or even dynamic display. In this review, we overview the development of meta-nanoprinting, including the physics of nanoprinting to manipulate optical amplitude and spectrum, single-functional meta-nanoprinting, multichannel meta-nanoprinting, dynamic meta-nanoprinting and multifunctional metasurface integrating nanoprinting with holography or metalens, etc. Applications of meta-nanoprinting such as image display, vortex beam generation, information decoding and hiding, information encryption, high-density optical storage and optical anti-counterfeiting have also been discussed. Finally, we conclude the opportunities and challenges/perspectives in this rapidly developing research field of meta-nanoprinting.

Two-dimensional (2D) materials exhibit fascinating and outstanding optoelectronic properties, laying the foundation for the development of novel optoelectronic devices. However, ultra-weak light absorption of 2D materials limits the performance of the optoelectronic devices. Here, a structure of MoS2/graphene/Au integrated onto the side-polished fiber (SPF) is proposed to achieve a high-performance fiber-integrated multifunction-in-one optoelectronic device. It is found that the device can absorb the transverse magnetic (TM) mode guided in the SPF and generate photocurrents as a polarization-sensitive photodetector, while the transverse electric (TE) mode passes with low loss through the device, making the device simultaneously a polarizer. In the device, the MoS2 film and the Au finger electrode can enhance the TM absorption by 1.75 times and 24.8 times, respectively, thus allowing to achieve high performance: a high photoresponsivity of 2.2 × 105 A/W at 1550 nm; the external quantum efficiency (EQE) of 1.76 × 107%; a high photocurrent polarization ratio of 0.686 and a polarization efficiency of 3.9 dB/mm at C-band. The integration of 2D materials on SPF paves the way to enhance the light–2D material interaction and achieve high performance multifunction-in-one fiber-integrated optoelectronic devices.

Abstract In this paper, we have reported a multifunctional device from graphene/TiO2/p-Si heterojunction, followed by its systematical analysis of optical response in a device under ultraviolet–visible-infrared band and transmission changes of terahertz waves in the 0.3–1.0 THz band under different bias voltages. It is found that photodetector in the “back-to-back” p-n-p energy band structure has a seriously unbalanced distribution of photogenerated carriers in the vertical direction when light is irradiated from the graphene side. So this ensures a higher optical gain of the device in the form of up to 3.6 A/W responsivities and 4 × 1013 Jones detectability under 750 nm laser irradiation. Besides, the addition of TiO2 layer in this terahertz modulator continuously widens the carrier depletion region under negative bias, thereby realizing modulation of the terahertz wave, making the modulation depth up to 23% under − 15 V bias. However, almost no change is observed in the transmission of terahertz wave when a positive bias is applied. A similar of an electronic semiconductor diode is observed that only allows the passage of terahertz wave for negative bias and blocks the positive ones. Graphic Abstract

Metasurfaces provide a novel platform for multifunctional devices due to their incomparable competence for the manipulation of different optical properties. Recently, many works have emerged to merge distinct functions into a single metasurface, which effectively increase the information density and capacity of meta-devices. In this work, combining the dual-wavelength polarizer and the orientation degeneracy of the Malus law, we further exploit the design degree of freedom of the metasurface, and realize color control and phase manipulation simultaneously with single-sized nanostructures. We experimentally demonstrate our concept by integrating the function of pseudo-color nanoprinting and holographic image display together. Our research can effectively improve the functionalities of metasurface and promote advanced research of multimode displays, information encryption, optical multiplexing, and many other related fields.

Numerous works that have demonstrated the study and enhancement of switching properties of ZnO-based RRAM devices are discussed. Several native point defects that have a direct or indirect effect on ZnO are discussed. The use of doping elements, multi-layered structures, suitable bottom and top electrodes, controlling the deposition materials, and the impact of hybrid structure for enhancing the switching dynamics are discussed. The potentials of ZnO-based RRAM for invisible and bendable devices are also covered. ZnO-based RRAM has the potential for possible application in bio-inspired cognitive computational systems. Thus, the synapse capability of ZnO is presented. The sneak-path current issue also besets ZnO-based RRAM crossbar array architecture. Hence, various attempts to subdue the bottleneck have been shown and discussed in this article. Interestingly, ZnO provides not only helpful memory features. However, it demonstrates the ability to be used in nonvolatile multifunctional memory devices. Also, this review covers various issues like the effect of electrodes, interfacial layers, proper switching layers, appropriate fabrication techniques, and proper annealing settings. These may offer a valuable understanding of the study and development of ZnO-based RRAM and should be an avenue for overcoming RRAM challenges.

The unusual electromagnetic responses of nanostructured metasurfaces endow them with an ability to manipulate the four fundamental properties (amplitude, phase, polarization, and frequency) of lightwave at the subwavelength scale. Based on this, in the past several years, a lot of innovative optical elements and devices, such as metagratings, metalens, metaholograms, printings, vortex beam generators, or even their combinations, have been proposed, which have greatly empowered the advanced research and applications of metasurfaces in many fields. Behind these achievements are scientists’ continuous exploration of new physics and degrees of freedom in nanostructured metasurface design. This review will focus on the progress on the design of different nanostructured metasurfaces for lightwave manipulation, including by varying/fixing the dimensions and/or orientations of isotropic/anisotropic nanostructures, which can therefore provide various functionalities for different applications. Exploiting the design degrees of freedom of optical metasurfaces provides great flexibility in the design of multifunctional and multiplexing devices, which can be applied in anticounterfeiting, information encoding and hiding, high-density optical storage, multichannel imaging and displays, sensing, optical communications, and many other related fields.

Abstract Multiferroic nanomaterials have attracted great interest due to simultaneous two or more properties such as ferroelectricity, ferromagnetism, and ferroelasticity, which can promise a broad application in multifunctional, low-power consumption, environmentally friendly devices. Bismuth ferrite (BiFeO3, BFO) exhibits both (anti)ferromagnetic and ferroelectric properties at room temperature. Thus, it has played an increasingly important role in multiferroic system. In this review, we systematically discussed the developments of BFO nanomaterials including morphology, structures, properties, and potential applications in multiferroic devices with novel functions. Even the opportunities and challenges were all analyzed and summarized. We hope this review can act as an updating and encourage more researchers to push on the development of BFO nanomaterials in the future.

The occurrence of opportunistic local infections and improper integration of metallic implants results in severe health conditions. Protective and tunable coatings represent an attractive and challenging selection for improving the metallic devices’ biofunctional performances to restore or replace bone tissue. Composite materials based on hydroxyapatite (HAp), Kanamycin (KAN), and fibroblast growth factor 2 (FGF2) are herein proposed as multifunctional coatings for hard tissue implants. The superior cytocompatibility of the obtained composite coatings was evidenced by performing proliferation and morphological assays on osteoblast cell cultures. The addition of FGF2 proved beneficial concerning the metabolic activity, adhesion, and spreading of cells. The KAN-embedded coatings exhibited significant inhibitory effects against bacterial biofilm development for at least two days, the results being superior in the case of Gram-positive pathogens. HAp-based coatings embedded with KAN and FGF2 protein are proposed as multifunctional materials with superior osseointegration potential and the ability to reduce device-associated infections.

Metasurfaces offer great opportunities to control electromagnetic (EM) waves, attracting intensive attention in science and engineering communities. Recently, many efforts were devoted to multifunctional metasurfaces integrating different functionalities into single flat devices. In this article, we present a concise review on the development of multifunctional metasurfaces, focusing on the design strategies proposed and functional devices realized. We first briefly review the early efforts on designing such systems, which simply combine multiple meta-structures with distinct functionalities to form multifunctional devices. To overcome the low-efficiency and functionality cross-talking issues, a new strategy was proposed, in which the meta-atoms are carefully designed single structures exhibiting polarization-controlled transmission/reflection amplitude/phase responses. Based on this new scheme, various types of multifunctional devices were realized in different frequency domains, which exhibit diversified functionalities (e.g., focusing, deflection, surface wave conversion, multi-beam emissions, etc.), for both pure-reflection and pure-transmission geometries or even in the full EM space. We conclude this review by presenting our perspectives on this fast-developing new sub-field, hoping to stimulate new research outputs that are useful in future applications.