Realization of advanced bio-interactive electronic devices requires mechanically compliant sensors with the ability to detect extremely large strain. Here, we design a new multifunctional carbon nanotube (CNT) based capacitive strain sensors which can detect strains up to 300% with excellent durability even after thousands of cycles. The CNT-based strain gauge devices exhibit deterministic and linear capacitive response throughout the whole strain range with a gauge factor very close to the predicted value (strictly 1), representing the highest sensitivity value. The strain tests reveal the presented strain gauge with excellent dynamic sensing ability without overshoot or relaxation, and ultrafast response at sub-second scale. Coupling these superior sensing capabilities to the high transparency, physical robustness and flexibility, we believe the designed stretchable multifunctional CNT-based strain gauge may have various potential applications in human friendly and wearable smart electronics, subsequently demonstrated by our prototypical data glove and respiration monitor.
The processing technique of bamboo particle board using laccase-treated calcium lignosulfonate was investigated and optimized. We studied the influence of enzyme amount, calcium ligosulfonate amount and hot pressing temperature on different particle board properties. All three factors were significant difference at different levels. There has significant differences between enzyme amount and Modulus of Rupture (MOR)，Modulus of Elasticity (MOE), Thickness Swelling (TS) (P<0.01)and Internal Bonding Strength (IB) (P<0.1). There has significant differences between Calcium lignosulfonate amount and MOR，TS(P<0.01), IB(P<0.05) and MOE (P<0.1). There has significant differences between hot pressing temperature and MOE，TS(P<0.01) and IB(P<0.1), but no significant differences on MOR. The optimum condition for board making as follows: enzyme amount 50u•g-1，calcium lignosulfonate amount 10%，hot pressing pressure 3.0MPa， 200°C and 7min while 0.75g•cm-3 board density and 10 mm thickness.
Three kinds of particles which produced by the processing of bamboo flooring were taken as the raw materials and analyzed of chemical constituents. Cellulose crystallinity and the reactive oxygen species (ROS) free radicals produced from laccase-treated bamboo were examined by X-ray Diffraction (XRD) and Electron Spin Resonance (ESR), respectively. Physical and mechanical properties of laccase treated bamboo particle boards which made from surplus materials of bamboo flooring process were investigated. In order to provide some theoretical basis for producing particle board with the surplus materials of bamboo flooring process by using laccase, the relations between physical properties and chemical constituents, cellulose crystallinity or the ROS free radicals of bamboo particle boards were researched.
In this work, a novel three-dimensional (3D) composite (GBS) based on melamine foam is fabricated by layer-by-layer self-assembly of positively charged hexagonal boron nitride ( h -BN) and negatively charged graphene oxide (GO) nanosheets. Improved tribological and thermal management performance are achieved by combing GBS with two different polymers (thermosetting epoxy and phase-reversible paraffin wax). First, the 3D-structure GBS not only solves the problem of the dispersion of additives in the epoxy but also significantly reduces the friction coefficient of 0.15 and wear rate (2.3 [[EQUATION]] ), as well as improves the thermal conductivity (1.48 W/(m [[EQUATION]] k), with a corresponding thermal conductivity enhancement of 1039.16%). Second, the compressed GO/ h -BN sponge is immersed in phase-changeable paraffin to fabricate the thermal management film, which effectively transfers and releases heat to cool the heat-generating components through ternary synergistic effect. Fascinatingly, the composite film also presents excellent self-lubricating and wear-resistance properties, contributing to improved durability in practical applications. In summary, the study and mechanism analysis of tribological performance and thermal management based on two polymers can help solve the heat transfer and packaging problems of integrated circuits and electronic devices in the future.
Physically transient electronics have attracted increasing attention recently due to their potential as the basis for building "green" electronics and biomedical devices. In the development of transient devices for biomedical applications, however, the dilemma between the strictly required biodegradability and device performance has brought great difficulties to the material selection. In this paper, we introduced silk fibroin as dielectric layer to fabricate biodegradable resistive memory devices. Comprising a W/silk fibroin/Mg sandwich structure, stable bipolar resistive switching behavior with good repeatability and device variability was obtained, surpassing most organic resistive memory and comparable to inorganic resistive memory. The carrier-transport evolution process was carefully examined to reveal the mechanism behind resistive switching. A switching model regarding the formation of metallic conductive filament was proposed by considering both the nature of silk fibroin dielectric layer and the key role of active metal electrode. Furthermore, the solubility test in phosphate-buffered saline indicates the device exhibiting physically transient behavior and good biodegradability. Good mechanical property and flexibility were also demonstrated through electrical testing under different bending conditions. These results suggest that our device is a promising memory element candidate for constructing transient electronic system, especially for biomedical applications.
In this letter, by utilizing the unique property of large hysteresis of threshold selector, a novel operation scheme is proposed to not only lower the voltages and power, but also remove the voltage matching constrains between resistive memory (RRAM) and selector. This makes threshold selector suitable for most of RRAM integration.
Memristive devices, having a huge potential as artificial synapses for low‐power neural networks, have received tremendous attention recently. Despite great achievements in demonstration of plasticity and learning functions, little progress has been made in the repeatable analog resistance states of memristive devices, which is, however, crucial for achieving controllable synaptic behavior. The controllable behavior of synapse is highly desired in building neural networks as it helps reduce training epochs and diminish error probability. Fundamentally, the poor repeatability of analog resistance states is closely associated with the random formation of conductive filaments, which consists of oxygen vacancies. In this work, graphene quantum dots (GQDs) are introduced into memristive devices. By virtue of the abundant oxygen anions released from GQDs, the GQDs can serve as nano oxygen‐reservoirs and enhance the localization of filament formation. As a result, analog resistance states with highly tight distribution are achieved with nearly 85% reduction in variations. In addition the insertion of GQDs can alter the energy band alignment and boost the tunneling current, which leads to significant reduction in both switching voltages and their distribution variations. This work may pave the way for achieving artificial neural networks with accurate and efficient learning capability.
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