The effect of degumming conditions on the functionality of silk fibroin films
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Identification, deterioration, and protection of organic cultural heritages from a modern perspective
Organic substances such as fibroin, collagen, and cellulose are vital components of organic cultural heritages, carrying significant ancient cultural information. However, their sensitivity to environmental factors leads to heritage deterioration and reduction of values. This review briefly introduces the composition of several major organic cultural heritages (silk fabrics, leather, parchment, paper, and wood), focusing on their multilayer structure of the molecules. All aspects of organic heritages are evaluated from surface to interior using modern analytical techniques. Furthermore, the review covers the different deterioration mechanisms of organic cultural heritages by temperature, humidity, light, air pollutants, and microorganisms. Hydrolysis and oxidation are the main deterioration formats during all types of cultural heritages. The original degradation of silk fabrics and paper took place in the amorphous region, while both the crystalline and amorphous regions are destroyed as aging progresses. Compared to silk fabrics, leather and parchment are more prone to suffer bio-deterioration due to the weakness of the covalent bonds between the tanning agent and collagen. Compared to traditional contact conservation methods, contactless methods provide protection while avoiding damage to the fragile and precious organic heritages, which promotes the development of biopolymer-based composites as a promising alternative. In conclusion, it describes potential challenges and prospects for the appropriate conservation of organic cultural heritages. The comprehensive exploration of organic cultural heritages from a modern perspective is expected to promote its preservation and the transmission of history and culture.
The enhanced ferroelectric properties of flexible Hf0.85Ce0.15O2 thin films based on in situ stress regulation
As the core component of ferroelectric memories, HfO2-based ferroelectric thin films play a crucial role in achieving their excellent storage performance. Here, we improved the ferroelectric properties and domain switching properties through in situ stress loading during annealing. The thin films are annealed under different bending states by applying different stress actions, and it is observed that, within a certain range of stress bending, the optimization of the ferroelectric properties of the annealed thin films can reach an extreme value. Specifically, under the influence of a small electric field, the 2Pr values of thin films annealed at +10 and −10 mm increased by 87.1% and 71.1%, respectively, compared with the unbent films. Additionally, these thin films exhibit extremely high domain wall mobility and excellent domain switching capabilities. Once the ferroelectric phase is formed through in situ stress modulation, it remains stable even under multiple service environments.
Combustion-assisted low-temperature ZrO2/SnO2 films for high-performance flexible thin film transistors
We developed high-performance flexible oxide thin-film transistors (TFTs) using SnO2 semiconductor and high-k ZrO2 dielectric, both formed through combustion-assisted sol-gel processes. This method involves the exothermic reaction of fuels and oxidizers to produce high-quality oxide films without extensive external heating. The combustion ZrO2 films were revealed to have an amorphous structure with a higher proportion of oxygen corresponding to the oxide network, which contributes to the low leakage current and frequency-independent dielectric properties. The ZrO2/SnO2 TFTs fabricated on flexible substrates using combustion synthesis exhibited excellent electrical characteristics, including a field-effect mobility of 26.16 cm2/Vs, a subthreshold swing of 0.125 V/dec, and an on/off current ratio of 1.13 × 106 at a low operating voltage of 3 V. Furthermore, we demonstrated flexible ZrO2/SnO2 TFTs with robust mechanical stability, capable of withstanding 5000 cycles of bending tests at a bending radius of 2.5 mm, achieved by scaling down the device dimensions.
Layer-by-layer assembly yields thin graphene films with near theoretical conductivity
Thin films fabricated from solution-processed graphene nanosheets are of considerable technological interest for a wide variety of applications, such as transparent conductors, supercapacitors, and memristors. However, very thin printed films tend to have low conductivity compared to thicker ones. In this work, we demonstrate a simple layer-by-layer deposition method which yields thin films of highly-aligned, electrochemically-exfoliated graphene which have low roughness and nanometer-scale thickness control. By optimising the deposition parameters, we demonstrate films with high conductivity (1.3 × 105 S/m) at very low thickness (11 nm). Finally, we connect our high conductivities to low inter-nanosheet junction resistances (RJ), which we estimate at RJ ~ 1kΩ.
Kinetic liquid metal synthesis of flexible 2D conductive oxides for multimodal wearable sensing
Transparent conducting oxides (TCOs) are crucial for high-performance displays, solar cells, and wearable sensors. However, their high process temperatures and brittle nature have hindered their use in flexible electronics. In this paper, we overturn these limitations by harnessing Cabrera-Mott oxidation to fabricate large-area, two-dimensional (2D) transparent electrodes via liquid metal printing. Our robotic, vacuum-free process deposits ultrathin (2–10 nm) indium tin oxide (ITO) with exceptional flexibility, transparency (>95%) and conductivity (>1300 S/cm) by utilizing hypoeutectic In-Sn alloys to print at <140 °C. Detailed characterization reveals the efficacy of Sn-doping and high crystallinity with large, platelike grains. The ultrathin nature enhances bending strain tolerance and scratch resistance, exceeding durability of PEDOT and offering low contact impedance to skin comparable to Ag/AgCl. We implement 2D ITO in synchronous, multimodal electrocardiography (ECG) and pulse plethysmography (PPG) measurements. This order-of-magnitude improvement to printed TCOs could enable wearable biometrics and display-integrated sensors.
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