Liquid Metal Droplets Wrapped with Polysaccharide Microgel as Biocompatible Aqueous Ink for Flexible Conductive Devices

Nanometerization of liquid metal in organic systems can facilitate deposition of liquid metals onto substrates and then recover its conductivity through sintering. Although having broader potential applications, producing stable aqueous inks of liquid metals keeps challenging because of rapid oxidation of liquid metal when exposing to water and oxygen. Here, a biocompatible aqueous ink is produced by encapsulating alloy nanodroplets of gallium and indium (EGaIn) into microgels of marine polysaccharides. During sonicating bulk EGaIn in aqueous alginate solution, alginate not only facilitates the downsizing process via coordination of their carboxyl groups with Ga ions but also forms microgel shells around EGaIn droplets. Due to the deceasing oxygen‐permeability of microgel shells, aqueous ink of EGaIn nanodroplets can maintain colloidal and chemical stability for a period of >7 d. Crosslinked alginate‐gel with tunable thickness can retard the generation and release of toxic cations, thereby affording high biocompatibility. The soft alginate shells also enable to recover electric conductivity of EGaIn layers by “mechanical sintering” for applications in microcircuits, electric‐thermal actuators, and wearable sensors, offering huge potential for electronic tattoos, artificial limbs, electric skins, etc.     

Mussel‐Inspired Adhesive and Conductive Hydrogel with Long‐Lasting Moisture and Extreme Temperature Tolerance

Conductive hydrogels are a promising class of materials to design bioelectronics for new technological interfaces with human body, which are required to work for a long‐term or under extreme environment. Traditional hydrogels are limited in short‐term usage under room temperature, as it is difficult to retain water under cold or hot environment. Inspired by the antifreezing/antiheating behaviors from nature, and based on mussel chemistry, an adhesive and conductive hydrogel is developed with long‐lasting moisture lock‐in capability and extreme temperature tolerance, which is formed in a binary‐solvent system composed of water and glycerol. Polydopamine (PDA)‐decorated carbon nanotubes (CNTs) are incorporated into the hydrogel, which assign conductivity to the hydrogel and serve as nanoreinforcements to enhance the mechanical properties of the hydrogel. The catechol groups on PDA and viscous glycerol endow the hydrogel with high tissue adhesiveness. Particularly, the hydrogel is thermal tolerant to maintain all the properties under extreme wide tempreature spectrum (?20 or 60 °C) or stored for a long term. In summary, this mussel‐inspired hydrogel is a promising material for self‐adhesive bioelectronics to detect biosignals in cold or hot environments, and also as a dressing to protect skin from injuries related to frostbites or burns.     

Memristor with Ag‐Cluster‐Doped TiO2 Films as Artificial Synapse for Neuroinspired Computing

Memristor, based on the principle of biological synapse, is recognized as one of the key devices in confronting the bottleneck of classical von Neumann computers. However, conventional memristors are difficult to continuously adjust the conduction and dutifully mimic the biosynapse function. Here, TiO₂ films with self‐assembled Ag nanoclusters implemented by gradient Ag dopant are employed to achieve enhanced memristor performance. The memristors exhibit gradual both potentiating and depressing conduction under positive and negative pulse trains, which can fully emulate excitation and inhibition of biosynapse. Moreover, comprehensive biosynaptic functions and plasticity, including the transition from short‐term memory to long‐term memory, long‐term potentiation and depression, spike‐timing‐dependent plasticity, and paired‐pulse facilitation, are implemented with the fabricated memristors in this work. The applied pulses with a width of hundreds of nanoseconds timescale are beneficial to realize fast learning and computing. High‐resolution transmission electron microscopy observations clearly demonstrate that Ag clusters redistribute to form Ag conductive filaments between Ag and Pt electrode under electrical field at ON‐state device. The experimental data confirm that the oxides doped with Ag clusters have the potential for mimicking biosynaptic behavior, which is essential for the further creation of artificial neural systems.     

A Self‐Healable,Highly Stretchable,and Solution Processable Conductive Polymer Composite for Ultrasensitive Strain and Pressure Sensing

Mimicking human skin's functions to develop electronic skins has inspired tremendous efforts in design and synthesis of novel soft materials with simplified fabrication methods. However, it still remains a great challenge to develop electronically conductive materials that are both stretchable and self‐healable. Here it is demonstrated that a ternary polymer composite comprised of polyaniline, polyacrylic acid, and phytic acid can exhibit high stretchability ( ≈ 500%) and excellent self‐healing properties. The polymer composite with optimized composition shows an electrical conductivity of 0.12 S cm^?1. On rupture, both electrical and mechanical properties can be restored with ≈ 99% efficiency in a 24 h period, which is enabled by the dynamic hydrogen bonding and electrostatic interactions. It is further shown that this composite is both strain and pressure sensitive, and therefore can be used for fabricating strain and pressure sensors to detect a variety of mechanical deformations with ultrahigh sensitivity. The sensitivity and sensing range are the highest among all of the reported self‐healable piezoresistive pressure sensors and even surpass most flexible mechanical sensors. Notably, this composite is prepared via a solution casting process, which potentially allows for large‐area, low‐cost fabrication electronic skins.     

Plasma-modified multiwalled carbon nanotubes with polyaniline for glucose biosensor applications

Multiwalled carbon nanotube (MWCNT) was modified through plasma polymerization of aniline by applying different radio frequency (radio frequency (RF): 13.56?MHz) powers. The modified MWCNTs were investigated in terms of morphology, chemical structure, and thermal behaviors, indicating the formation of composites based on the surface modification of MWCNT with polyaniline (PANI). These composites were then used in amperometric glucose biosensor, which was constructed by immobilizing glucose oxidase on premodified Pt electrode with PANI/MWCNT composites. The biosensor based on the composite obtained under RF power of 60?W exhibited the high sensitivity of 54.91?µA mM^?1 cm^?2 to glucose.     

电化学合成氧化钴/聚苯胺复合膜工艺研究

采用单因素对比试验对电化学合成氧化钴/聚苯胺复合膜工艺进行了研究,并利用电化学测试技术、扫描电子显微镜(SEM)和X射线衍射仪(XRD)对氧化钴/聚苯胺复合膜的性能进行测试。结果表明,采用恒电位法制备氧化钴/聚苯胺膜微观呈现为规则片状形貌,膜层覆盖均匀,其腐蚀电位-0.04 V,腐蚀电流47.42μA,10%HCl点滴腐蚀时间达382 s,10%NaOH点滴腐蚀时间达到364 s,中性盐雾实验48 h未见锈蚀。     

Ultraviolet Irradiation Effect on Polyvinylpyrrolidone/Polyaniline Films with Additives

Polyvinylpyrrolidone/polyaniline (PVP/PANI) with additives (TiO₂, ZnO, NaCl and Na₂SO₄) was synthesized. To spread the electric and photoelectric applications of PVP/PANI, its photodegradation under UV irradiation was studied by Fourier transform infrared spectroscopy, diffuse reflectance spectroscopy, water uptake and scanning electron microscopy. Results show that ZnO, TiO₂ and NaCl accelerate the photodegradation, respectively, but Na₂SO₄ stabilized PVP/PANI. The degradation rate of PVP/PANI/tert-butyl alcohol and PVP/PANI/ascorbic acid proved the radical role. Water uptake results show that the power of interactions is in this order: PVP/PANI/Na₂SO₄?>?PVP/PANI/TiO₂?>?PVP/PANI/ZnO?>?PVP/PANI?>?PVP/PANI/NaCl?>?PVP/PANI/tert-butyl alcohol>PVP/PANI/ascorbic acid.     

导电炭黑和沥青基短切碳纤维对丁腈橡胶性能的影响

研究导电炭黑及其与沥青基短切碳纤维(PCF)并用对丁腈橡胶(NBR)物理、导电和导热性能的影响。结果表明:随着导电炭黑用量增大,导电炭黑/NBR硫化胶的拉伸强度、撕裂强度和热导率均呈增大趋势,而体积电阻率呈阶梯形减小趋势;随着导电炭黑用量减小和PCF用量增大,导电炭黑/PCF/NBR硫化胶的拉伸强度和撕裂强度均明显减小,体积电阻率略有降低,而热导率呈线性增大趋势。     

导电填料和偶联剂Si69对电场下丁腈橡胶与铁热硫化粘合性能的影响

通过电化学反应法研究导电填料和偶联剂Si69对电场下丁腈橡胶(NBR)与铁(Fe)热硫化粘合性能的影响。结果表明:电场作用下,NBR与Fe界面层间形成化学键合,实现良好粘合;采用普通导电炭黑的硫化胶综合性能较好;电场强度和偶联剂Si69用量对NBR与Fe粘合性能以及硫化胶的物理性能和导电性能影响显著。