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Miniaturized and integrated polarization conversion devices have high potential application value, and switching devices that integrate absorption and polarization conversion are receiving increasing attention. However, most of these devices are reflective polarization conversion devices, and reflective devices have many inconveniences. Therefore, in this paper, we design bifunctional metamaterial devices that can be switched between transmission polarization conversion and absorption functions, which are composed of vanadium dioxide (VO2), polyimide, and gold. When VO2 is in the insulating state, the structure has a transmission polarization conversion function to realize the linear polarization conversion function. The polarization conversion rate exceeds 99.9% in the 0.2–1.4 THz range. The polarization conversion is explained by analyzing the distribution of surface currents and electric fields. When VO2 is in the metallic state, the structure has a multi-band absorption function. The peak absorption reaches 99.4% at 1.536 THz. The main reason for the strong absorption effect is explained by analyzing the distributions of surface currents, electric and magnetic fields in combination with the impedance matching theory. The device is tunable and multifunctional, and can be used in terahertz imaging, active switching and other fields. [ABSTRACT FROM AUTHOR]

• A multifunctional mechanical model with both amplified illusion and cloaking properties is proposed. • The amplified function can make a small object to produce the same displacement distribution as a large object. • Intelligent control system with the detective and control functions is introduced. • Effectively broaden the effective frequency range of structure in 3300Hz×4400 Hz and 1200Hz×3100 Hz. • The cloaking characteristics of the structure are verified through theoretical, numerical and experimental analysis. Illusion device can make an object to produce a field distribution different from its own, offering potential applications in diverse fields. In this work, we propose a multifunctional metamaterial with intelligent control systems, which exhibits amplified illusion and cloaking characteristics for detecting or hiding objects over different frequency ranges. The amplification function allows a small object to generate the same displacement distribution as a larger object, while the cloaking function renders an object invisible and undetectable. Simulation and experimental results demonstrate the exceptional amplification and cloaking properties of the multifunctional configuration. In contrast to single-function structures like cloaking and focusing, which can only fulfill a specific function, designing a multifunctional structure capable of achieving two or more properties within a single configuration presents a significant challenge. [ABSTRACT FROM AUTHOR]

The multimode optoelectronic operation in a single component device is an attractive design strategy for future optoelectronics, which demands unique and complex multifunction. Here, a novel dual‐mode optoelectronic device with both memory and switching functionalities by utilizing alternating metallic stripe domain regime‐induced controllable hysteresis of two dimensional (2D)‐crystalline VO2 films is reported. It is found that the formation and disappearance of tensile strain‐induced metallic stripe domain arrays are susceptible to temperature‐induced thermal energy, allowing controllable hysteresis in electric field‐induced metal‐insulator transition (E‐MIT) by tuning the total region of aligned metallic stripe domains within the VO2 films through current flow‐induced thermal energy. Based on the tunable hysteresis in E‐MIT, the 2D‐crystalline VO2 film‐based device exhibits successful multimode optoelectronic memory and switching operations. The device with a large hysteresis width exhibits high‐performance optoelectronic memory behavior with a high on/off ratio of up to ≈55% and a long retention time over 5000 s response to a light pulse optically triggering MIT. On the other hand, the 2D‐crystalline VO2 film device with a narrow hysteresis width exhibits high performance of photodetection with a responsivity of 316 mA W−1 and response times of ≈1.2 and ≈2 µs at rise and fall, respectively. [ABSTRACT FROM AUTHOR]

Terahertz waves have the characteristics of low energy and good transmittance, which have broad application prospects in communication, spectral detection of biological samples, radar imaging, and sensing. Conventional materials are difficult to interact with terahertz waves, and metamaterials have emerged as a way to modulate terahertz waves. However, after years of development, the traditional metamaterials are currently facing problems such as difficult to realize multi-functionality and non-tunable. Therefore, in this paper, a multifunctional tunable terahertz metamaterial is designed using the phase change material vanadium dioxide. This device can perform both transmission and absorption functions. Controlling the temperature can realize the functional conversion of the device, and when the temperature is low (20°C), the transmittance of the device is more than 90% when it operates at 0.48 THz, with good performance of the transmission function. And after increasing the temperature above the VO2 phase transition temperature (66°C), it can be used as a narrow-band absorber with an absorption rate as high as 99.3% at 1.247 THz (80°C), which achieves a perfect absorption effect. In addition, the device is tunable, and its absorption and transmission modulation amplitudes can reach 95.3 and 89%, respectively. [ABSTRACT FROM AUTHOR]

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.

In this paper, a Janus metastructure device (JMD) is proposed. The JMD design introduces asymmetric structures, which leads to the generation of analogous quantum optical effects when light is incident at large angles. Specifically, forward electromagnetic‐induced transparency (EIT) and backward narrowband absorption (NA) are achieved when light is incident along different directions, displaying Janus characteristics in the forward and backward directions. Additionally, the operating frequency of JMD can be controlled through the use of liquid crystal. Such features hold promising potential for various applications in photonic and optoelectronic fields. When the axial direction of the liquid crystal is oriented along the x‐direction, the JMD achieves a transparent window over 90% within 0.46–0.51 THz at forward incidence, and an absorption peak of 84.1% appears at 0.331 THz at backward incidence. When the axial direction is oriented along the y‐direction, the JMD achieves EIT in the range of 0.51–0.575 THz at forward incidence, and a backward absorption peak of 93.3% occurs at 0.305 THz. In addition, the performance changes at different polarization and incidence angles are presented. The mechanism of absorption generation, the method of suppressing excess absorption, and the parametric inversion of the electromagnetic characteristics of JMD are also discussed. [ABSTRACT FROM AUTHOR]

The development of multifunctional devices could represent a significant advancement in meeting the need for nano and micro technologies. Therefore, we have developed a Ag/Sb2Se3/FTO-based multifunction device having nanostructures, which works as an ultraviolet (UV) photodetector and a switching device. Our theory suggests how oxygen formation leads to detection in the UV range rather than detection in the infrared range, which is the natural detection range of Sb2Se3. The m–s–m photodetector device is based on the photoconductive phenomenon, and ultrafast transient absorption spectroscopy has been extensively used to investigate the charge carrier dynamics of Sb2Se3 films of 500 nm. At two distinct excitations, 375 nm UV and 532 nm visible light, and a pulse energy of 1 J per pulse, the effect of annealing on the charge carrier relaxation of the films was investigated. The kinetics of the hot charge carrier's decay and recombination were studied for both as-grown and annealed films. The proposed theory is analyzed with the help of X-ray photoelectron spectroscopy and density functional theory studies. The device shows external quantum efficiency values of 2.9 and 1.3 at 375 and 386 nm, respectively. The rise time to fall time ratio was 0.29/0.30 s at 375 nm irradiation at 2 V bias at a power density of 32 mW/cm2. The same device shows bipolar resistive switching, in which resistance shifts from a high resistance state to a low resistance state in a voltage sweep from −1 to 0 V and then 0 to 1 V. The result of the switching phenomenon is reasonably justified by the electrochemical metallization phenomenon. An outstanding accomplishment in electronic devices is combining two different features on a single device. [ABSTRACT FROM AUTHOR]

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.

The dual metamaterial induced transparency (dual-MIT) phenomenon, which can be significantly tailored via the depolarization field effect of the graphene overlayer, is demonstrated in our fabricated multifunctional terahertz metastructures composed of unequal-lengthed 3-bar arrays. Those metasurfaces could actively manipulate the phase and group delay at various frequencies, as well as the different polarization conversion capability. The introduction of graphene reinforces the amplitude modulation of dual MITs and further reduces the quenched power by 4 times with a rotated angle. Combined with carrier dynamics, the dual-MIT transient regulation can realize an ultrafast all-optical switch with 2-time enhancement in modulation speed. Based on the advantage of the dual-MIT windows with different frequencies and magnitudes, we have illustrated the encrypted imaging on the erasure and reappearance of the target pattern. Our work provides a lower power consumption option for ultrafast all-optical switch and opens up the opportunities for future communication and information security in terahertz regime. [Display omitted] • Spectral modulation of dual metamaterial induced transparency in hybrid structures. • Controllable manipulation of the phase, group delay, and ploarization conversion. • Switch power of dual-MIT is reduced by 4 times with the introduction of graphene. • Ultrafast all-optical switch possessing 2-time enhancement in modulation speed. • Encrypted imaging about the erasure and reappearance of the target pattern. [ABSTRACT FROM AUTHOR]

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.

Multi-functional magnetic sensors with tunable measure range can help cover different requirements from detecting weak field to sensing strong field. However, additional control system is often required to realize the tunability, which increases the complexity of device. In this work, we found the current controlled sensitivity and linear range in the NiCo2O4 thin film based anomalous hall sensor. The device owns not only simple structure but also interesting anomalous hall signal whose linearity range and sensitivity can be controlled by current. Ultrahigh sensitivity of 4900 V/(AT) in the range of ±0.2 mT and competitive sensitivity of 20 V/(AT) in the range of ±23 mT are simultaneously realized by tunning the work current. In addition, a memory switching characteristic controlled by magnetic field is further found in the device. These results show that the anomalous hall device has the potential for multifunctional compact device. [ABSTRACT FROM AUTHOR]

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.

This study introduces the Tympanic Membrane Metamaterial inspired acoustic Triboelectric Nanogenerator (TMM-TENG), which exhibits subwavelength structural dimensions and effective sound absorption within low-frequency ranges. The performance of acoustic energy harvesting is increased by replacing rigid bottom of the acoustic cavity with an elastic part and introducing a point-surface mechanism. Experimental tests employing the proposed mechanism are then conducted. The obtained results show a remarkable 2220 % increase in the output voltage of the TMM-TENG compared with the traditional approach. As for the acoustic energy harvesting performance, for a sound pressure level (SPL) of 95 dB, the peak-to-peak value of the output voltage reaches 500 V, with a measured current of 40 μA and a maximum output power of 3.05 mW. Moreover, the incorporation of an elastic part into the TMM-TENG proves advantageous in the manipulation of low-frequency sound waves. The acoustic performance of the device can also be regulated by adjusting the thickness of the elastic part. In addition, multiple TMM-TENGs with varying elastic part thicknesses are placed on a duct, and band-limited white noise is generated to evaluate the sound reduction ability without limiting the air ventilation. Furthermore, the mounted TMM-TENG allows to perform of self-powered wireless temperature sensing and acoustic telecommunication functionalities. [Display omitted] • A deep-subwavelength tympanic membrane metamaterial inspired TENG is proposed. • Simultaneous realization of acoustic energy harvesting and noise control is achieved. • Self-powered low-frequency acoustic telecommunication is demonstrated. [ABSTRACT FROM AUTHOR]

In this study, a fabrication method for a system composed of a fluorescence imaging module and a multielectrode array (MEA) chamber is described. It is important to measure both fluorescence intensity and electrical activity to obtain a better understanding of a physiological activity, such as spikes or action potentials, of cells. However, observing these physiological traits long-term with cultured cells is difficult using a conventional microscope. In this study, we developed a small fluorescence imaging device with an MEA that can be used in a conventional CO2 incubator. The fluorescence imaging module was composed of a CMOS image sensor, a fiber-optic plate (FOP), a blue LED, and optical filters. The FOP enabled the device to be miniaturized through lensless fluorescence imaging. The MEA chamber was fabricated with micro gold electrodes deposited on the FOP. By using the FOP for the bottom of the chamber, we measured both the fluorescence signal and electrophysiology signal in the same experiment. The performance of the device was evaluated with neuronal blastoma cells. Our device enabled us to observe fluorescence images and MEA signals. [ABSTRACT FROM AUTHOR]

In neuroscience, it is crucial to clarify the relationship between single-cell activity and neural network structure to understand brain neural activity. To this end, a device that can measure signals with high temporal resolution over a wide area is required. In this study, we developed a multifunctional implantable device for measuring deep-brain functions. The device conducts electrophysiological measurements using microelectrodes and fluorescence imaging using a CMOS image sensor, which enables observations of brain functions with high temporal resolution over a wide area. The device developed is implemented by stacking the microelectrode array and imaging device. We measured the activity of neurons in the ventral tegmental area (VTA) of mice using this device. We successfully recorded action potentials and confirmed that the developed microelectrodes are effective for measuring brain functions. Results suggest that the multifunctional implantable device developed can simultaneously perform electrophysiological measurements and fluorescence imaging using a CMOS image sensor. However, the noise generated during imaging should be eliminated in the future. The activation of γ-aminobutyric acid neurons was also confirmed upon the intraperitoneal injection of nicotine solution as a pharmacological stimulus. The device developed with integrated microelectrodes and a CMOS image sensor is unprecedented and can prove useful in understanding the relationship between neuronal activity and neural networks. [ABSTRACT FROM AUTHOR]

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.

This paper presents a low profile, multifunctional microwave device, which behaves either as a dual‐polarized filtering antenna or as a lowpass filter. For the dual‐polarized filtering antenna, two introduced quarter‐wavelength open‐circuit stubs can generate a radiation null at the lower frequency stopband to obtain good frequency selectivity. Moreover, to improve the out‐of‐band radiation suppression level at high frequencies, the C‐shaped short‐circuit stubs and U‐shaped metal strips are loaded at feeding structures. In the case of the filter, the feeding network and part of the patchwork together to form a lowpass filter. The overall height of the designed microwave device is only 0.05 wavelengths at 2.6 GHz. The results show that the average gain is 8.09 ± 0.54 dBi in the antenna frequency band with out‐of‐band gain suppression level of 25.1 dB. Moreover, when the device act as a lowpass filter, the insertion loss between the two ports is less than 0.7 dB at the lower working band. [ABSTRACT FROM AUTHOR]

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 FROM AUTHOR]

Inspired by the intriguing adaptivity of natural life, such as squids and flowers, we propose a series of dynamic and responsive multifunctional devices based on multiscale structural design, which contain metal nanocoating layers overlaid with other micro-/nanoscale soft or rigid layers. Since the optical/photothermal properties of a metal nanocoating are thickness dependent, metal nanocoatings with different thicknesses were chosen to integrate with other structural design elements to achieve dynamic multistimuli responses. The resultant devices demonstrate 1) strain-regulated cracked and/or wrinkled topography with tunable light-scattering properties, 2) moisture/photothermal-responsive structural color coupled with wrinkled surface, and 3) mechanically controllable light-shielding properties attributed to the strain-dependent crack width of the nanocoating. These devices can adapt external stimuli, such as mechanical strain, moisture, light, and/or heat, into corresponding changes of optical signals, such as transparency, reflectance, and/or coloration. Therefore, these devices can be applied as multistimuli-responsive encryption devices, smart windows, moisture/photothermal-responsive dynamic optics, and smartphone app-assisted pressure-mapping sensors. All the devices exhibit high reversibility and rapid responsiveness. Thus, this hybrid system containing ultrathin metal nanocoatings holds a unique design flexibility and adaptivity and is promising for developing next-generation multifunctional devices with widespread application. [ABSTRACT FROM AUTHOR]

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.

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., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2024 The Authors.)

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. [ABSTRACT FROM AUTHOR]

Multifunctional self-powered sensors play a crucial role in various applications, ranging from body healthcare monitoring to environmental sensing. Herein, we developed a multifunctional moist-electric generator (MMEG), integrating energy harvesting, power supply and sensing in a single device. Two electrodes are on the same side of the poly (4-styrensulfonic acid) active film to construct a laterally dual gradient device The exposed areas of active film and the areas covered with electrodes naturally create a humidity gradient upon moisture, and meanwhile an ion gradient is generated on the surface of the active layer by asymmetric electrodes. The MMEG device has a small effective exposed film area of only 0.01×1 cm2 and provides a stable electrical output of 1 V and an unparalleled power density of 874 μW·cm−2 in humid environments. Due to good linear response and remarkable sensitivity (85700%), the MMEG is applied in self-powered humidity sensors of various scenarios, such as humidity sensors, respiration monitoring, non-contact sensing, sweat monitoring, and ultra-fast tactile sensing with a response time of 0.05 s. This work demonstrates a high-performance self-powered humidity sensing from self-humidity energy, rather than other energy types, and provides a general and effective strategy for the development of next-generation multifunctional self-powered devices. [Display omitted] • A Multifunctionally moist-electric generator (MMEG) was developed based on laterally dual gradient. • The MMEG integrated energy harvesting, power supply and sensing, and provided ultra-high power density of 874 μW·cm−2. • The MMEG exhibited excellent performance, response/recovery (0.68 s/ 3.06 s), linearity (R2 =0.994), sensitivity (85700%). • The MMEG has been applied in respiration monitoring, non-contact sensing, sweat monitoring, and ultra-fast tactile sensing. [ABSTRACT FROM AUTHOR]

The negative differential resistance (NDR) effect was observed in a Pt/BiFeO 3 /TiO 2 /BiFeO 3 /Pt memory cell by using light-illumination as extra stimulation. Further, the coexistence appearances and gradually becomes obvious when the device is exposed to light-illumination, which display an excellent stability and reversibility of the coexistence of NDR and resistive switching (RS) at room temperature. Through analysis of the physical conduction mechanism, it is expected that a large number of photo-generated charge carriers are induced under light-illumination on the surface and interface of the heterojunction is responsible for the appearance of this coexistence phenomenon. Importantly, the NDR effect is strengthened by the competition transfer of charge carrier in the polarized electric field under light-illumination. This work shows that the coexistence of light-modulated NDR and RS can deeply explore the potential applications of light-controlled multifunctional devices. Image 1 • The appearance of NDR in a RS memory is observed under light-illumination. • The device displays a stable coexistence of NDR and RS at room temperature. • Photo-generated carriers are responsible for the appearance of NDR phenomenon. • The NDR is strengthened by competition transfer of carriers in the polarized field. • Coexistence of NDR and RS indicate the potential multifunctional applications. [ABSTRACT FROM AUTHOR]

Highlights: The development of bismuth ferrite as a multiferroic nanomaterial is summarized. The morphology, structures, and properties of bismuth ferrite and its potential applications in multiferroic devices with novel functions are presented and discussed. Some perspectives and issues needed to be solved are described.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. [ABSTRACT FROM AUTHOR]

In this work, a multifunctional metastructure (MS) that combines the functions of a circular-to-linear polarization conversion (PC) and sensing is presented. The device uses a 2 × 2 array of three layers of media as the unit structure to modulate an incident circularly polarized wave into a linearly polarized one by reflection in the terahertz (THz) band. Its output linear polarized wave axial ratio (AR) is larger than 20 dB in the 1.61–2.638 THz range, with a relative bandwidth of 48% and an insertion loss below 4%. In addition, filling the device with liquids of different refractive indices shifts the frequency of the sharp AR peak generated by its output linear polarized wave. Utilizing this property, the device can also be used a refractive index sensor. When the thickness of the liquid to be measured is 2 μm, the device has a frequency sensitivity of 178 GHz/RIU (refractive index unit) and a figure of merit (FOM) of 12.7. Parameters and angles are also discussed and the principle is analyzed through current density plots. The given design can be applied in satellite communication systems, signal modulation, and sensing. • The MS achieves circular-to-linear polarization conversion. • The MS realizes refractive index sensor. • The MS realizes a multifunctional device combining a circular-to-linear polarization converter and a sensor. • The MS discusses the effect of different parameters as well as angles on performance. [ABSTRACT FROM AUTHOR]

• The proposed LPS can achieve the function of isolator and switch with one structure. • The presented LPS has the angle stabilization. • The presented LPS enable high isolation, extinction ratio and low insertion loss. • Multiple parameters can be adjusted to manipulate the transmission frequency and bandwidth. • The proposed LPS can be applied to the area of communication and computer. In this paper, a multifunctional device based on a one-dimensional (1-D) magnetized InSb layered photonic structure (LPS) that can achieve the function of a magnetic-controlled isolator and switch is proposed, with the advantages of multi-function. The external conditions for realizing the LPS function are temperature 303 K, magnetic field B 1 = 0–0.3 T, B 2 = 0 T, which are easier to obtain through an applied magnetic field device. B 1 and B 2 differ only in intensity. Both B 1 and B 2 are applied magnetic fields parallel to the positive y -axis. The change of magnetic field can influence the the cyclotron frequency of the electron which affect the dielectric constant of the tensor form, and finally lead to the change of refractive index (RI), resulting in interesting electromagnetic phenomena. Temporal inversion symmetry and spatial inversion symmetry could be easily broken to actualize nonreciprocal phenomena because of the magneto-optic effect of Indium antimonide (InSb) and an asymmetric arrangement of quasi-periodic media. For the isolator, the transmittance of forwarding propagation arrives at 0.994 and the backward scale is much closer to 0. The isolation and insertion loss achieves 34 dB and 0.0269 dB, and the range of the angle stabilization is from 17° to 31°. For the switch operating, just changing the value of B 1 from 0.3 T to 0 T, can realize the function of the switch operating instead of an isolator. This shift is easier to reach by turning off the magnetic field. The extinction ratio attains 99.8 % and angle stabilization is between 9° and 31°. This magnetic-structure multifunctional LPS can play a vital constructive role in medicine, computing, and other fields. [ABSTRACT FROM AUTHOR]

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.

Abstract In this paper, we propose and theoretically investigate a tunable stacked graphene metasurface, which can independently manipulate electromagnetic field at different terahertz frequency. By tuning the Fermi levels of graphene ribbons, the designed two-layers graphene ribbons can realize a required phase shift of ∼ 2 π for manipulating the terahertz wavefronts owing to the excitation of plasmon resonances at each layer of graphene ribbons. A reflective double-frequencies focusing metalens has been designed working at 3.5 THz and 7.0 THz. For the designed lens with focal lengths of 300 μ m , the focus depth of 3.5 THz and 7.0 THz electromagnetic wave (full width at half maximum along the Z direction) is 174. 7 μ m and 84 μ m , respectively. In addition, the resolution of focal points (full width at half maximum along the X direction) are close to the half-wavelength in the focusing plane, which are 48. 2 μ m and 21. 5 μ m respectively, demonstrating that the proposed metalens have superior performance. Furthermore, the focal length and offset distance of focal point of the lens can be tuned actively by changing gate voltages. The present graphene metasurface paves the way to engineering various potential applications for tunable, multiband, multifunctional metasurfaces. Highlights • A tunable stacked graphene metasurface can manipulate THz wavefronts. • Required phase shifts can be realized by changing the Fermi levels. • A double-frequency lens works at 3.5 THz and 7.0 THz respectively. • The focal length and offset distance of focal point can be tuned effectively. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

This paper presents the implementation of a single piece of macro fiber composite (MFC) piezoelectric transducer as a multifunctional device for both strain sensing and energy harvesting for the first time in the context of an energy harvesting powered wireless sensing system. The multifunction device is achieved via time-multiplexing operation for alternating dynamic strain sensing and energy harvesting functions at different time slots associated with different energy levels, that is, when there is insufficient energy harvested in the energy storage for powering the system, the MFC is used as an energy harvester for charging up the storage capacitor; otherwise, the harvested energy is used for powering the system and the MFC is used as a strain sensor for measuring dynamic structural strain. A circuit is designed and implemented to manage the single piece of MFC as the multifunctional device in a time-multiplexing manner, and the operation is validated by the experimental results. The dynamic strains measured by the MFC in the implemented system match a commercial strain sensor of extensometer by 95.5 to 99.99%, and thus the studied method can be used for autonomous structural health monitoring of dynamic strain. [ABSTRACT FROM AUTHOR]

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.