Project description:Despite the promise of high flexibility and conformability of hydrogel ionic conductors, existing polymeric conductive hydrogels have long suffered from compromises in mechanical, electrical, and cryoadaptive properties due to monotonous functional improvement strategies, leading to lingering challenges. Here, we propose an all-in-one strategy for the preparation of poly(acrylic acid)/cellulose (PAA/Cel) hydrogel ionic conductors in a facile yet effective manner combining acrylic acid and salt-dissolved cellulose, in which abundant zinc ions simultaneously form strong coordination interactions with the two polymers, while free solute salts contribute to ionic conductivity and bind water molecules to prevent freezing. Therefore, the developed PAA/Cel hydrogel simultaneously achieved excellent mechanical, conductive, and cryogenically adaptive properties, with performances of 42.5 MPa for compressive strength, 1.6 MPa for tensile strength, 896.9% for stretchability, 9.2 MJ m-3 for toughness, 59.5 kJ m-2 for fracture energy, and 13.9 and 6.2 mS cm-1 for ionic conductivity at 25 and -70 °C, respectively. Enabled by these features, the resultant hydrogel ionic conductor is further demonstrated to be assembled as a self-powered electronic skin (e-skin) with high signal-to-noise ratio for use in monitoring movement and physiological signals regardless of cold temperatures, with hinting that could go beyond high-performance hydrogel ionic conductors.
Project description:Understanding the nature of charge carriers at the LaAlO3/SrTiO3 interface is one of the major open issues in the full comprehension of the charge confinement phenomenon in oxide heterostructures. Here, we investigate thermopower to study the electronic structure in LaAlO3/SrTiO3 at low temperature as a function of gate field. In particular, under large negative gate voltage, corresponding to the strongly depleted charge density regime, thermopower displays high negative values of the order of 10(4)-10(5) μVK(-1), oscillating at regular intervals as a function of the gate voltage. The huge thermopower magnitude can be attributed to the phonon-drag contribution, while the oscillations map the progressive depletion and the Fermi level descent across a dense array of localized states lying at the bottom of the Ti 3d conduction band. This study provides direct evidence of a localized Anderson tail in the two-dimensional electron liquid at the LaAlO3/SrTiO3 interface.
Project description:Combinations of ionic liquids (ILs) with antimicrobial compounds have been shown to produce synergistic activities in model liposomes. In this study, imidazolium chloride-based ILs with alkyl tail length variations are combined with commercially available, small-molecule antimicrobials to examine the potential for combinatorial and synergistic antimicrobial effects on P. aeruginosa, E. coli, S. aureus, and S. cerevisiae. The effects of these treatments in a human cell culture model indicate the cytotoxic limits of ILs paired with antimicrobials. The analysis of these ILs demonstrates that the length of the alkyl chain on the IL molecule is proportional to both antimicrobial activity and cytotoxicity. Moreover, the ILs which exhibit synergy with small-molecule antibiotics appear to be acting in a membrane permeabilizing manner. Collectively, results from these experiments demonstrate an increase in antimicrobial efficacy with specific IL + antimicrobial combinations on microbial cultures while maintaining low cytotoxicity in a mammalian cell culture model.
Project description:We demonstrate that the giant magnetoresistance can be switched off (on) in even- (odd-) width zigzag graphene-like nanoribbons by an atomistic gate potential or edge disorder inside the domain wall in the antiparallel (ap) magnetic configuration. A strong magneto-thermopower effect is also predicted that the spin thermopower can be greatly enhanced in the ap configuration while the charge thermopower remains low. The results extracted from the tight-binding model agree well with those obtained by first-principles simulations for edge doped graphene nanoribbons. Analytical expressions in the simplest case are obtained to facilitate qualitative analyses in general contexts.
Project description:Ionic thermoelectrics show great potential in thermal sensing owing to their ultrahigh thermopower, low cost, and ease in production. However, the lack of effective n-type ionic thermoelectric materials seriously hinders their applications. Here, we report giant and bidirectionally tunable thermopowers within an ultrawide range from −15 to +17 mV K−1 in solid ionic liquid–based ionogels. Particularly, a record high negative thermopower of −15 mV K−1 is achieved in the ternary ionogel, rendering it among the best n-type ionic thermoelectric materials under the same condition. A thermopower regulation strategy through ion doping to selectively induce ion aggregates to enhance ion-ion interactions is proposed. These selective ion interactions are found to be decisive in modulating the sign and magnitude of the thermopower in the ionogels. A prototype wearable device integrated with 12 p-n pairs is demonstrated with a total thermopower of 0.358 V K−1, showing promise for ultrasensitive thermal detection.
Project description:There has been increasing interest in the emerging ionic thermoelectric materials with huge ionic thermopower. However, it's challenging to selectively tune the thermopower of all-solid-state polymer materials because the transportation of ions in all-solid-state polymers is much more complex than those of liquid-dominated gels. Herein, this work provides all-solid-state polymer materials with a wide tunable thermopower range (+20~-6 mV K-1), which is different from previously reported gels. Moreover, the mechanism of p-n conversion in all-solid-state ionic thermoelectric polymer material at the atomic scale was presented based on the analysis of Eastman entropy changes by molecular dynamics simulation, which provides a general strategy for tuning ionic thermopower and is beneficial to understand the fundamental mechanism of the p-n conversion. Furthermore, a self-powered ionic thermoelectric thermal sensor fabricated by the developed p- and n-type polymers demonstrated high sensitivity and durability, extending the application of ionic thermoelectric materials.
Project description:The influence of the linking group between the phosphoryl and bridging moieties in phosphoryl-containing task-specific ionic liquids (TSILs) on the extraction of uranyl ions was experimentally and theoretically investigated. A novel phosphoramidate-based TSIL with an amine group as the linking moiety resulted in a higher uranyl ion extraction efficiency compared with that of other phosphoryl-based TSILs. A distribution ratio of 4999 ± 51 can be achieved for uranyl ions. The uranyl ions (76.7 ± 1.5%) were stripped from the loaded ionic liquid phase in a single stage using 0.05 M diethylenetriamine pentaacetic acid in a 1.0 M guanidine carbonate solution. The extraction stoichiometry of the uranyl ions was determined by a slope analysis of the extraction data. Furthermore, the fundamental nature of the interaction between the phosphoramidate-based TSIL and uranyl ions was theoretically studied for the first time. The theoretical calculations demonstrated that the synergistic effect of the complexation interaction and H-bond formation between the phosphoramidate-functional ionic liquid and uranyl nitrate led to the higher extraction efficiency. These results provide a basis for rational design, synthesis and potential applications of novel TSILs for uranyl extraction.
Project description:Flexible power supply devices provide possibilities for wearable electronics in the Internet of Things. However, unsatisfying capacity or lifetime of typical batteries or capacitors seriously limit their practical applications. Different from conventional heat-to-electricity generators, zinc ion thermal charging cells has been a competitive candidate for the self-power supply solution, but the lack of promising cathode materials has restricted the achievement of promising performances. Herein, we propose an attractive cathode material by rational heterostructure engineering of hydrated vanadium pentoxide. Owing to the integration of thermodiffusion and thermoextraction effects, the thermopower is significantly improved from 7.8 ± 2.6 mV K-1 to 23.4 ± 1.5 mV K-1. Moreover, an impressive normalized power density of 1.9 mW m-2 K-2 is achieved in the quasi-solid-state cells. In addition, a wearable power supply constructed by three units can drive the commercial health monitoring system by harvesting body heat. This work demonstrates the effectiveness of electrodes design for wearable thermoelectric applications.
Project description:Introducing hydration layers to hydrogel microspheres (HMs) by coating the surface with liposomes can effectively reduce friction. However, the lubrication can be inactivated when the surface coatings are damaged. To endow HMs with the ability to form self-renewable hydration layers and maintain cellular homeostasis, rapamycin-liposome-incorporating hyaluronic acid-based HMs (RAPA@Lipo@HMs) were created using microfluidic technology and photopolymerization processes. The RAPA@Lipo@HMs improve joint lubrication by using a smooth rolling mechanism and continuously exposing liposomes on the outer surface to form self-renewable hydration layers via frictional wear. In addition, the released autophagy activator (rapamycin)-loaded cationic liposomes can target negatively charged cartilage through electrostatic interactions and maintain cellular homeostasis by increasing autophagy. Furthermore, the in vivo data showed that the RAPA@Lipo@HMs can alleviate joint wear and delay the progression of osteoarthritis. The RAPA@Lipo@HMs can provide efficient lubrication and potentially alleviate friction-related diseases such as osteoarthritis.
Project description:Local drug delivery directly to the source of a given pathology using retrodialysis is a promising approach to treating otherwise untreatable diseases. As the primary material component in retrodialysis, the semipermeable membrane represents a critical point for innovation. This work presents a new ionic hydrogel based on polyethylene glycol and acrylate with dopamine counterions. The ionic hydrogel membrane is shown to be a promising material for controlled diffusive delivery of dopamine. The ionic nature of the membrane accelerates uptake of cationic species compared to a nonionic membrane of otherwise similar composition. It is demonstrated that the increased uptake of cations can be exploited to confer an accelerated transport of cationic species between reservoirs as is desired in retrodialysis applications. This effect is shown to enable nearly 10-fold increases in drug delivery rates from low concentration solutions. The processability of the membrane is found to allow for integration with microfabricated devices which will in turn accelerate adaptation into both existing and emerging device modalities. It is anticipated that a similar materials design approach may be broadly applied to a variety of cationic and anionic compounds for drug delivery applications ranging from neurological disorders to cancer.