Graphene strain sensors have promising prospects of applications in detecting human motion. However, the shortage of graphene growth and patterning techniques has become a challenging issue hindering ...the application of graphene strain sensors. Therefore, we propose wafer-scale flexible strain sensors with high-performance, which can be fabricated in one-step laser scribing. The graphene films could be obtained by directly reducing graphene oxide film in a Light-Scribe DVD burner. The gauge factor (GF) of the graphene strain sensor (10 mm × 10 mm square) is 0.11. In order to enhance the GF further, graphene micro-ribbons (20 μm width, 0.6 mm long) has been used as strain sensors, of which the GF is up to 9.49. The devices may conform to various application requirements, such as high GF for low-strain applications and low GF for high deformation applications. The work indicates that laser scribed flexible graphene strain sensors could be widely used in medical-sensing, bio-sensing, artificial skin and many other areas.
Respiration is as one of the most essential physiological signals, which can be used to monitor human healthcare and activities. Herein, we report a flexible, lightweight and highly conductive porous ...graphene network as the humidity sensor for respiration monitoring. To enhance the sensing performance, the graphene oxide (GO), poly (3, 4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT: PSS) and Ag colloids (AC) were used to modify the porous graphene. The humidity properties of porous based graphene networks have been investigated at different relative humidity (RH). The porous based graphene sensors exhibit excellent capability of monitoring different breathing patterns including mouse and nose respiration, normal and deep respiration. Besides, the signal variations before and after water intake was recorded by the sensor, which demonstrates the ability to monitor water loss during breathing period. Furthermore, the humidity sensor shows the ability to detect physiological activities including skin moisture, speaking and whistle rhythm, which could be a promising electronic for clinical respiration monitoring.
•A novel porous graphene network was first fabricated as humidity sensor.•Surface modification has been developed to improve the humidity sensing performance.•The respiration monitoring of porous graphene based humidity sensor has been systematically demonstrated.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
As digital security demands continue to rise, physical unclonable functions (PUFs) have emerged as a potential solution for providing unique identifiers and cryptographic keys. However, conventional ...memory‐based PUFs have limited encoding capacity, which can compromise their security. Herein, an Ag nanowire‐based PUF that offers a high encoding capacity is introduced. The prototype PUF leverages the intrinsic topology of the nanowire network for encoding, which enables to achieve encoding capacities that are on the order of nn−2. The encoding method for a 4‐node PUF is validated and its encoding capacity distribution at binary and ternary bit levels is assessed. The ternary bit encoding method allows for more detailed differentiation of the internal topological connection structure of the PUF, resulting in a larger encoding capacity. Additionally, an authentication system that is proposed. For a 7 × 7 array PUF, the estimated decryption time is ≈1.5*1058 years, demonstrating the PUF's resistance to attacks. The Ag nanowire‐based PUF design offers a promising approach to enhancing authentication system security and overcoming limitations of existing PUFs. Further exploration of this innovative PUF technology in the realm of hardware security can have significant implications for digital security in modern devices.
Ag nanowire‐based physical unclonable functions (PUFs) are introduced to address the limited encoding capacity of conventional electrical PUFs, providing unique cryptographic keys for enhanced digital security. The nanowire topology enables high encoding capacities, while ternary bit encoding allows for detailed differentiation and larger capacity. The proposed authentication system offers strong resistance to attacks, making it a promising solution for hardware security in modern devices.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
Extremely low energy consumption neuromorphic computing is required to achieve massively parallel information processing on par with the human brain. To achieve this goal, resistive memories based on ...materials with ionic transport and extremely low operating current are required. Extremely low operating current allows for low power operation by minimizing the program, erase, and read currents. However, materials currently used in resistive memories, such as defective HfO x , AlO x , TaO x , etc., cannot suppress electronic transport (i.e., leakage current) while allowing good ionic transport. Here, we show that 2D Ruddlesden–Popper phase hybrid lead bromide perovskite single crystals are promising materials for low operating current nanodevice applications because of their mixed electronic and ionic transport and ease of fabrication. Ionic transport in the exfoliated 2D perovskite layer is evident via the migration of bromide ions. Filaments with a diameter of approximately 20 nm are visualized, and resistive memories with extremely low program current down to 10 pA are achieved, a value at least 1 order of magnitude lower than conventional materials. The ionic migration and diffusion as an artificial synapse is realized in the 2D layered perovskites at the pA level, which can enable extremely low energy neuromorphic computing.
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IJS, KILJ, NUK, PNG, UL, UM
Visual optical information encryption–decryption and anti‐counterfeiting (IEDAC) technology play a vital role in the field of information security. Recent luminescent information encryption ...technologies face the disadvantages of depending on external large‐scale stimulus decryption equipment, inability to read out repeatedly, and information leakage, impeding the practical applications of luminescence encryption. Here, an integrated luminescent IEDAC chip is proposed, which provides a convenient approach to store and decipher pre‐patterned luminescence information based on laser engraved template and film heater. The luminescent encryption chip contains a double‐layer structure made up of long persistent phosphors based on SrCaGa4O8 host and a laser induced graphene heater, which makes it possible to decrypt information on a single chip. This design enables dual‐mode (photoluminescence/long persistent luminescence), dual‐color (blue/yellow‐green), and multi‐level IEDAC function, providing a novel insight and integrated strategy for implementing advanced IEDAC technologies.
An integrated luminescent information encryption–decryption and anti‐counterfeiting chip made up of long persistent phosphors and a laser induced graphene heater is proposed, which provides a convenient approach to store and decipher pre‐patterned luminescence information on a single chip. This portable chip achieves dual‐mode/dual‐color luminescence and multi‐level encryption, and anti‐counterfeiting function.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
There is a growing need for developing machine learning applications. However, implementation of the machine learning algorithm consumes a huge number of transistors or memory devices on-chip. ...Developing a machine learning capability in a single device has so far remained elusive. Here, we build a Markov chain algorithm in a single device based on the native oxide of two dimensional multilayer tin selenide. After probing the electrical transport in vertical tin oxide/tin selenide/tin oxide heterostructures, two sudden current jumps are observed during the set and reset processes. Furthermore, five filament states are observed. After classifying five filament states into three states of the Markov chain, the probabilities between each states show convergence values after multiple testing cycles. Based on this device, we demo a fixed-probability random number generator within 5% error rate. This work sheds light on a single device as one hardware core with Markov chain algorithm.
Direct conversion of methane to high value‐added oxygenates under mild conditions has attracted extensive interest. However, the over‐oxidation of target products is usually unavoidable due to the ...easily excessive activation of C−H bond on the sites of supported metal species. Here, we identified the most efficient Zr‐oxo nodes of UiO‐66 metal‐organic frameworks (MOFs) catalysts for the selective oxidation of methane with H2O2. These nodes were modified by three types of benzene 1, 4‐dicarboxylates (NH2‐BDC, H2BDC, and NO2‐BDC). Detailed characterizations and DFT calculations revealed that these ligands can effectively tune the electronic properties of Zr‐oxo nodes and the H2BDC ligand led to optimal electronic density of Zr‐oxo nodes in UiO‐66. Thus the UiO‐66‐H catalyst promoted the formation of ⋅OH species that adsorbed on Zr‐oxo nodes, and facilitated the activation of methane with a lower energy barrier and subsequent conversion to hydroxylation oxygenates with 100 % selectivity.
UiO‐66 metal‐organic frameworks (MOFs) catalysts modified with various ligands can directly convert CH4 into oxygenates with 100 % selectivity by using H2O2 as an oxidant under mild conditions. The Zr‐oxo nodes have different electronic properties that affected the anchoring of ⋅OH species to form effective Zroxo−⋅OH sites. These sites promote the activation of the C−H bond of CH4.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
Recently, wearable pressure sensors have attracted tremendous attention because of their potential applications in monitoring physiological signals for human healthcare. Sensitivity and linearity are ...the two most essential parameters for pressure sensors. Although various designed micro/nanostructure morphologies have been introduced, the trade-off between sensitivity and linearity has not been well balanced. Human skin, which contains force receptors in a reticular layer, has a high sensitivity even for large external stimuli. Herein, inspired by the skin epidermis with high-performance force sensing, we have proposed a special surface morphology with spinosum microstructure of random distribution via the combination of an abrasive paper template and reduced graphene oxide. The sensitivity of the graphene pressure sensor with random distribution spinosum (RDS) microstructure is as high as 25.1 kPa–1 in a wide linearity range of 0–2.6 kPa. Our pressure sensor exhibits superior comprehensive properties compared with previous surface-modified pressure sensors. According to simulation and mechanism analyses, the spinosum microstructure and random distribution contribute to the high sensitivity and large linearity range, respectively. In addition, the pressure sensor shows promising potential in detecting human physiological signals, such as heartbeat, respiration, phonation, and human motions of a pushup, arm bending, and walking. The wearable pressure sensor array was further used to detect gait states of supination, neutral, and pronation. The RDS microstructure provides an alternative strategy to improve the performance of pressure sensors and extend their potential applications in monitoring human activities.
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IJS, KILJ, NUK, PNG, UL, UM
In this work, a thin-film transistor gas sensor based on the p-N heterojunction is fabricated by stacking chemical vapor deposition-grown tungsten disulfide (WS2) with a sputtered ...indium–gallium–zinc-oxide (IGZO) film. To the best of our knowledge, the present device has the best NO2 gas sensor response compared to all the gas sensors based on transition-metal dichalcogenide materials. The gas-sensing response is investigated under different NO2 concentrations, adopting heterojunction device mode and transistor mode. High sensing response is obtained of p-N diode in the range of 1–300 ppm with values of 230% for 5 ppm and 18 170% for 300 ppm. On the transistor mode, the gas-sensing response can be modulated by the gate bias, and the transistor shows an ultrahigh response after exposure to NO2, with sensitivity values of 6820% for 5 ppm and 499 400% for 300 ppm. Interestingly, the transistor has a typical ambipolar behavior under dry air, while the transistor becomes p-type as the amount of NO2 increases. The assembly of these results demonstrates that the WS2/IGZO device is a promising platform for the NO2-gas detection, and its gas-modulated transistor properties show a potential application in tunable engineering for two-dimensional material heterojunction-based transistor device.
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IJS, KILJ, NUK, PNG, UL, UM
The flexible pressure sensor is one of the essential components of the wearable device, which is a critical solution to the applications of artificial intelligence and human–computer interactions in ...the future. Due to its simple manufacturing process and measurement methods, research related to piezoresistive mechanical sensors is booming, and those sensors are already widely used in industry. However, existing pressure sensors are almost all based on negative resistance variations, making it difficult to reach a balance between the sensitivity and the detection range. Here, we demonstrated a low-cost flexible pressure sensor with a positive resistance–pressure response based on laser scribing graphene. The sensor can be customized and modulated to achieve both an ultrahigh sensitivity and a broad detection range. Furthermore, the device possesses the signal amplification property like a mechanical triode under the external pressure bias. Based on its amplification ability, varieties of physiological signals and human movements have been detected using our devices; then, an integrated gait monitoring system has been realized. The reported positive graphene pressure sensor has outstanding capability, showing a wide application range such as intelligent perception, an interactive device, and real-time health/motion monitoring.
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IJS, KILJ, NUK, PNG, UL, UM
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