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1.
J Mater Chem B ; 8(20): 4387-4394, 2020 May 27.
Artigo em Inglês | MEDLINE | ID: mdl-32373848

RESUMO

Researchers developing implantable neural probes face a dilemma. Rigid neural probes facilitate direct implantation, but the brain tissue suffers from a vulnerable interface and a strong neuroinflammatory response due to mechanical mismatch between the probe and the brain tissue. Flexible neural probes offer stable interfaces and eliminate neuroinflammatory responses but require auxiliary implantation. Here, we have created a new kind of micro fiber-shaped neural probe with alterable elastic moduli before and after implantation. Carbon nanotube fibers and calcium crosslinked sodium alginate functioned as the core electrode and sheath layer, respectively. The response of calcium crosslinked sodium alginate to water will alter the probe elastic moduli from ∼10 GPa to ∼10 kPa post implantation, which is close to the elastic modulus of brain tissue. The micro fiber probes were directly implanted into mouse brains without any additional materials. After implantation, they became soft and offered dynamically adaptable interfaces with a reduced inflammatory response, benefiting long-term monitoring of neuron signals. Continuous four week monitoring of neuron signals was achieved. The simplicity of the strategy makes it suitable for versatile neuron techniques in neuron recording and modulation.

2.
Artigo em Inglês | MEDLINE | ID: mdl-32342610

RESUMO

Electronic textiles may revolutionize many fields, such as communication, health care and artificial intelligence. To date, unfortunately, computing with them is not yet possible. Memristors are compatible with the interwoven structure and manufacturing process in textiles because of its two-terminal crossbar configuration. However, it remains a challenge to realize textile memristors owing to the difficulties in designing advanced memristive materials and achieving high-quality active layers on fiber electrodes. Herein we report a robust textile memristor based on an electrophoretic-deposited active layer of deoxyribonucleic acid (DNA) on fiber electrodes. The unique architecture and orientation of DNA molecules with the incorporation of Ag nanoparticles offer the best-in-class performances, e.g., both ultra-low operation voltage of 0.3 V and power consumption of 100 pW and high switching speed of 20 ns. Fundamental logic calculations such as implication and NAND are demonstrated as functions of textile chips, and it has been thus integrated with power-supplying and light emitting modules to demonstrate an all-fabric information processing system.

3.
Adv Mater ; 32(5): e1904697, 2020 02.
Artigo em Inglês | MEDLINE | ID: mdl-32017287
4.
J Mater Chem B ; 8(16): 3371-3381, 2020 Apr 29.
Artigo em Inglês | MEDLINE | ID: mdl-31951232

RESUMO

Chemical biosensors that can target analytes in a variety of biological fluids have been widely studied in recent decades. Extensive efforts have been made to design and build user-friendly, in situ tissue-interfaced biosensors with multiple integrated functions, miniaturized footprint and improved selectivity, sensitivity and stability. This review article presents the recent advances of these tissue-interfaced chemical biosensors. We start with a short introduction to the detection mechanism and design principles of soft chemical biosensors and then focus on the architectures, properties and applications of different types of such biosensors. The remaining challenges and future directions are finally highlighted for future research.

5.
Adv Mater ; 32(8): e1906806, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31950562

RESUMO

Oxygen evolution reaction (OER) catalysts that function efficiently in pH-neutral electrolyte are of interest for biohybrid fuel and chemical production. The low concentration of reactant in neutral electrolyte mandates that OER catalysts provide both the water adsorption and dissociation steps. Here it is shown, using density functional theory simulations, that the addition of hydrated metal cations into a Ni-Fe framework contributes water adsorption functionality proximate to the active sites. Hydration-effect-promoting (HEP) metal cations such as Mg2+ and hydration-effect-limiting Ba2+ into Ni-Fe frameworks using a room-temperature sol-gel process are incorporated. The Ni-Fe-Mg catalysts exhibit an overpotential of 310 mV at 10 mA cm-2 in pH-neutral electrolytes and thus outperform iridium oxide (IrO2 ) electrocatalyst by a margin of 40 mV. The catalysts are stable over 900 h of continuous operation. Experimental studies and computational simulations reveal that HEP catalysts favor the molecular adsorption of water and its dissociation in pH-neutral electrolyte, indicating a strategy to enhance OER catalytic activity.

6.
Adv Mater ; 32(5): e1901971, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31273843

RESUMO

Modern electronic devices are moving toward miniaturization and integration with an emerging focus on wearable electronics. Due to their close contact with the human body, wearable electronics have new requirements including low weight, small size, and flexibility. Conventional 3D and 2D electronic devices fail to efficiently meet these requirements due to their rigidity and bulkiness. Hence, a new family of 1D fiber-shaped electronic devices including energy-harvesting devices, energy-storage devices, light-emitting devices, and sensing devices has risen to the challenge due to their small diameter, lightweight, flexibility, and weavability into soft textile electronics. The application challenges faced by fiber and textile electronics from single fiber-shaped devices to continuously scalable fabrication, to encapsulation and testing, and to application mode exploration, are discussed. The evolutionary trends of fiber and textile electronics are then summarized. Finally, future directions required to boost their commercialization are highlighted.

7.
Nat Biomed Eng ; 4(2): 159-171, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31659307

RESUMO

Mechanical mismatches between implanted electronics and biological tissues can lead to inaccurate readings and long-term tissue damage. Here, we show that functionalized multi-walled carbon nanotubes twisted into helical fibre bundles that mimic the hierarchical structure of muscle can monitor multiple disease biomarkers in vivo. The flexible fibre bundles are injectable, have a low bending stiffness and display ultralow stress under compression. As proof-of-concept evidence of the sensing capabilities of these fibre bundles, we show that the fibre bundles enable the spatially resolved and real-time monitoring of H2O2 when implanted in tumours in mice, and that they can be integrated with a wireless transmission system on an adhesive skin patch to monitor calcium ions and glucose in the venous blood of cats for 28 d. The versatility of the helical fibre bundles as chemically functionalized electrochemical sensors makes them suitable for multiple sensing applications in biomedicine and healthcare.

8.
Angew Chem Int Ed Engl ; 59(6): 2273-2278, 2020 Feb 03.
Artigo em Inglês | MEDLINE | ID: mdl-31743581

RESUMO

Rechargeable aqueous zinc-ion batteries are attractive because of their inherent safety, low cost, and high energy density. However, viable cathode materials (such as vanadium oxides) suffer from strong Coulombic ion-lattice interactions with divalent Zn2+ , thereby limiting stability when cycled at a high charge/discharge depth with high capacity. A synthetic strategy is reported for an oxygen-deficient vanadium oxide cathode in which facilitated Zn2+ reaction kinetic enhance capacity and Zn2+ pathways for high reversibility. The benefits for the robust cathode are evident in its performance metrics; the aqueous Zn battery shows an unprecedented stability over 200 cycles with a high specific capacity of approximately 400 mAh g-1 , achieving 95 % utilization of its theoretical capacity, and a long cycle life up to 2 000 cycles at a high cathode utilization efficiency of 67 %. This work opens up a new avenue for synthesis of novel cathode materials with an oxygen-deficient structure for use in advanced batteries.

9.
Small ; 15(52): e1905903, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31769588

RESUMO

Metal anodes, such as zinc and bismuth have been regarded as ideal materials for aqueous batteries due to high gravimetrical capacity, high abundance, low toxicity, and intrinsic safety. However, their translation into practical applications are hindered by the low mass loading (≈1 mg cm-2 ) of active materials. Here, the multiscale integrated structural engineering of 3D scaffold and active material, i.e., bismuth is in situ intercalated in reduced graphene oxide (rGO) wall of network, are reported. Tailoring the rapid charge transport on rGO 3D network and facile access to nano- and microscale bismuth, the rGO/Bi hybrid anode shows high utilization efficiency of 91.4% at effective high load density of ≈40 mg cm-2 , high areal capacity of 3.51 mAh cm-2 at the current density of 2 mA cm-2 and high reversibility of >10 000 cycles. The resulting Ni-Bi full battery exhibits high areal capacity of 3.13 mAh cm-2 at the current density of 2 mA cm-2 , far outperforming the other counterpart batteries. It represents a general and efficient strategy in enhancing the battery performance by designing hierarchically networked structure.

10.
Angew Chem Int Ed Engl ; 58(47): 16820-16825, 2019 Nov 18.
Artigo em Inglês | MEDLINE | ID: mdl-31535447

RESUMO

The electrocatalytic urea oxidation reaction (UOR) provides more economic electrons than water oxidation for various renewable energy-related systems owing to its lower thermodynamic barriers. However, it is limited by sluggish reaction kinetics, especially by CO2 desorption steps, masking its energetic advantage compared with water oxidation. Now, a lattice-oxygen-involved UOR mechanism on Ni4+ active sites is reported that has significantly faster reaction kinetics than the conventional UOR mechanisms. Combined DFT, 18 O isotope-labeling mass spectrometry, and in situ IR spectroscopy show that lattice oxygen is directly involved in transforming *CO to CO2 and accelerating the UOR rate. The resultant Ni4+ catalyst on a glassy carbon electrode exhibits a high current density (264 mA cm-2 at 1.6 V versus RHE), outperforming the state-of-the-art catalysts, and the turnover frequency of Ni4+ active sites towards UOR is 5 times higher than that of Ni3+ active sites.

11.
Angew Chem Int Ed Engl ; 58(47): 17054-17060, 2019 Nov 18.
Artigo em Inglês | MEDLINE | ID: mdl-31523899

RESUMO

Despite efforts to stabilize sodium metal anodes and prevent dendrite formation, achieving long cycle life with high areal capacities remains difficult owing to a combination of complex failure modes that involve retardant uneven sodium nucleation and subsequent dendrite formation. Now, a sodiophilic interphase based on oxygen-functionalized carbon nanotube networks is presented, which concurrently facilitates a homogeneous sodium nucleation and a dendrite-free, lateral growth behavior upon recurring sodium plating/stripping processes. This sodiophilic interphase renders sodium anodes with an ultrahigh capacity of 1078 mAh g-1 (areal capacity of 10 mAh cm-2 ), approaching the theoretical capacity of 1166 mAh g-1 of pure sodium, as well as a long cycle life up to 3000 cycles. Implementation of this anode allows for the construction of a sodium-air battery with largely enhanced cycling performance owing to the oxygen functionalization-mediated, dendrite-free sodium morphology.

12.
Nat Commun ; 10(1): 3302, 2019 Jul 24.
Artigo em Inglês | MEDLINE | ID: mdl-31341162

RESUMO

Rechargeable sodium metal batteries with high energy density could be important to a wide range of energy applications in modern society. The pursuit of higher energy density should ideally come with high safety, a goal difficult for electrolytes based on organic solvents. Here we report a chloroaluminate ionic liquid electrolyte comprised of aluminium chloride/1-methyl-3-ethylimidazolium chloride/sodium chloride ionic liquid spiked with two important additives, ethylaluminum dichloride and 1-ethyl-3-methylimidazolium bis(fluorosulfonyl)imide. This leads to the first chloroaluminate based ionic liquid electrolyte for rechargeable sodium metal battery. The obtained batteries reached voltages up to ~ 4 V, high Coulombic efficiency up to 99.9%, and high energy and power density of ~ 420 Wh kg-1 and ~ 1766 W kg-1, respectively. The batteries retained over 90% of the original capacity after 700 cycles, suggesting an effective approach to sodium metal batteries with high energy/high power density, long cycle life and high safety.

13.
Nat Commun ; 10(1): 2790, 2019 06 26.
Artigo em Inglês | MEDLINE | ID: mdl-31243276

RESUMO

We previously demonstrated that for long-term spastic limb paralysis, transferring the seventh cervical nerve (C7) from the nonparalyzed side to the paralyzed side results in increase of 17.7 in Fugl-Meyer score. One strategy for further improvement in voluntary arm movement is selective activation of five target muscles innervated by C7 during recovery process. In this study, we develop an implantable multisite optogenetic stimulation device (MOSD) based on shape-memory polymer. Two-site stimulation of sciatic nerve bundles by MOSD induces precise extension or flexion movements of the ankle joint, while eight-site stimulation of C7 nerve bundles induce selective limb movement. Long-term implant of MOSD to mice with severed and anastomosed C7 nerve is proven to be both safe and effective. Our work opens up the possibility for multisite nerve bundle stimulation to induce highly-selective activations of limb muscles, which could inspire further applications in neurosurgery and neuroscience research.


Assuntos
Luz , Dispositivos Ópticos , Neurônios Retinianos/efeitos da radiação , Nervo Isquiático/efeitos da radiação , Animais , Comportamento Animal , Simulação por Computador , Camundongos , Método de Monte Carlo , Ratos
14.
Small ; 15(18): e1805493, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-30945787

RESUMO

Flexible devices integrated with sensing and energy storage functions are highly desirable due to their potential application in wearable electronics and human motion detection. Here, a flexible film is designed in a facile and low-cost leaf templating process, comprising wrinkled carbon nanotubes (CNTs) as the conductive layer and patterned polydimethylsiloxane (PDMS) with bio-inspired microstructure as a soft substrate. Assembled from wrinkled CNTs on patterned PDMS film, a strain sensor is realized to possess sensitive resistance response against various deformations, producing a resistance response of 0.34%, 0.14%, and 9.1% under bending, pressing, and 20% strain, respectively. Besides, the strain sensor can reach a resistance response of 3.01 when stretched to 44%. Furthermore, through the electro-deposition of polyaniline, the CNTs film is developed into a supercapacitor, which exhibits a specific capacitance of 176 F g-1 at 1 A g-1 and a capacitance retention of 88% after 10 000 cycles. In addition, the fabricated supercapacitor shows super flexibility, delivering a capacitance retention of 98% after 180° bending for 100 cycles, 95% after 45° twisting for 100 cycles, and 98% after 100% stretching for 400 cycles. The superior capacitance stability demonstrates that the design of wrinkled CNTs-based electrodes fixed by microstructures is beneficial to the excellent electrochemical performance.

15.
Angew Chem Int Ed Engl ; 58(39): 13643-13653, 2019 Sep 23.
Artigo em Inglês | MEDLINE | ID: mdl-30986329

RESUMO

As a new direction in applied chemistry, fiber electronics allow device configuration to evolve from three to two dimensions and then to one dimension. The reduction in dimension brings unique properties, such as ultraflexibility, tissue adaptability, and weavability, enabling their use in a variety of applications, particularly in various emerging fields related to implantable devices and wearable systems. The different types of fiber electrode materials are summarized based on the one-dimensional configuration and their distinctive interfaces, various devices, and promising applications. The remaining challenges and future directions are finally highlighted.

16.
ACS Appl Mater Interfaces ; 11(4): 4345-4352, 2019 Jan 30.
Artigo em Inglês | MEDLINE | ID: mdl-30609342

RESUMO

Flexible strain sensors have attracted extensive attention in electronic skins and health monitoring systems. To date, it remains a great challenge for the development of a multifunctional strain sensor with simultaneous ultralow detection limit, broad sensing range, and high repeatability. In this paper, we report a new carbon nanotube/flexible fiber-shaped strain sensor. The fiber substrate has a novel microstructure where a highly elastic rubber fiber core is tightly wound by a continuous spring-like polypropylene fiber as the shell. Our sensor offers combined sensing performances of ultralow detection limit of 0.01% strain, wide sensing range of 200% strain, and high repeatability of 20 000 cycles by designing double-leveled helical gaps. This strain sensor shows a rapid response time of 70 ms under both stretching and releasing. In addition, it is available for a variety of other deformations such as bending and torsion. Due to the unique fiber structure, it can extend the torsion detection range to 1000 rad m-1. On the basis of the superior sensing performances, our sensor demonstrates to efficiently work for both subtle physiological activities and vigorous human motions. This work provides a general and effective strategy for designing smart wearable devices with high performance.


Assuntos
Dispositivos Eletrônicos Vestíveis , Limite de Detecção , Nanotubos de Carbono/química , Polipropilenos/química
17.
Angew Chem Int Ed Engl ; 58(8): 2437-2442, 2019 Feb 18.
Artigo em Inglês | MEDLINE | ID: mdl-30575248

RESUMO

Although lithium-oxygen batteries possess a high theoretical energy density and are considered as promising candidates for next-generation power systems, the enhancement of safety and cycling efficiency of the lithium anodes while maintaining the high energy storage capability remains difficult. Here, we overcome this challenge by cross-stacking aligned carbon nanotubes into porous networks for ultrahigh-capacity lithium anodes to achieve high-performance lithium-oxygen batteries. The novel anode shows a reversible specific capacity of 3656 mAh g-1 , approaching the theoretical capacity of 3861 mAh g-1 of pure lithium. When this anode is employed in lithium-oxygen full batteries, the cycling stability is significantly enhanced, owing to the dendrite-free morphology and stabilized solid-electrolyte interface. This work presents a new pathway to high performance lithium-oxygen batteries towards practical applications by designing cross-stacked and aligned structures for one-dimensional conducting nanomaterials.

18.
Angew Chem Int Ed Engl ; 57(49): 16114-16119, 2018 Dec 03.
Artigo em Inglês | MEDLINE | ID: mdl-30315718

RESUMO

Enhancing the p-orbital delocalization of a Bi catalyst (termed as POD-Bi) via layer coupling of the short inter-layer Bi-Bi bond facilitates the adsorption of intermediate *OCHO of CO2 and thus boosts the CO2 reduction reaction (CO2 RR) rate to formate. X-ray absorption fine spectroscopy shows that the POD-Bi catalyst has a shortened inter-layer bond after the catalysts are electrochemically reduced in situ from original BiOCl nanosheets. The catalyst on a glassy carbon electrode exhibits a record current density of 57 mA cm-2 (twice the state-of-the-art catalyst) at -1.16 V vs. RHE with an excellent formate Faradic efficiency (FE) of 95 %. The catalyst has a record half-cell formate power conversion efficiency of 79 % at a current density of 100 mA cm-2 with 93 % formate FE when applied in a flow-cell system. The highest rate of the CO2 RR production reported (391 mg h-1 cm2 ) was achieved at a current density of 500 mA cm-2 with formate FE of 91 % at high CO2 pressure.

19.
Chemistry ; 24(69): 18271-18292, 2018 Dec 10.
Artigo em Inglês | MEDLINE | ID: mdl-30156031

RESUMO

Carbon dioxide electroreduction and water splitting are known as two promising strategies to convert renewable intermittent electrical energy into chemical energy. Thus, the three half-reactions, namely, CO2 reduction reaction, hydrogen evolution reaction, and the oxygen evolution counter reaction, in these two electrolytic processes have attracted wide research interest. Organic polymer electrocatalysts or electrocatalysts containing organic components play important roles in these catalytic processes. It has been shown that the organic molecules can efficiently catalyze the reactions themselves, and modulate the active sites towards high selectivity and efficiency. The roles of the organic molecules in conducting polymers, the metal complexes, and the framework materials are extracted for the three half-reactions mentioned above, and this comprehensive review will serve as a guide for future research and aid in the design of electrocatalysts related to organic molecules.

20.
Adv Mater ; 30(43): e1803165, 2018 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-30160338

RESUMO

Solar radiation, especially ultraviolet (UV) light, is a major hazard for most skin-related cancers. The growing needs for wearable health monitoring systems call for a high-performance real-time UV sensor to prevent skin diseases caused by excess UV exposure. To this end, here a novel self-powered p-CuZnS/n-TiO2 UV photodetector (PD) with high performance is successfully developed (responsivity of 2.54 mA W-1 at 0 V toward 300 nm). Moreover, by effectively replacing the Ti foil with a thin Ti wire for the anodization process, the conventional planar rigid device is artfully turned into a fiber-shaped flexible and wearable one. The fiber-shaped device shows an outstanding responsivity of 640 A W-1 , external quantum efficiency of 2.3 × 105 %, and photocurrent of ≈4 mA at 3 V, exceeding those of most current UV PDs. Its ultrahigh photocurrent enables it to be easily integrated with commercial electronics to function as a real-time monitor system. Thus, the first real-time wearable UV radiation sensor that reads out ambient UV power density and transmits data to smart phones via wifi is demonstrated. This work not only presents a promising wearable health monitor, but also provides a general strategy for designing and fabricating smart wearable electronic devices.


Assuntos
Monitoramento de Radiação/instrumentação , Raios Ultravioleta , Desenho de Equipamento , Humanos , Nanocompostos/química , Processos Fotoquímicos , Energia Solar , Luz Solar , Titânio/química , Dispositivos Eletrônicos Vestíveis
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