Neuromorphic electro-stimulation based on atomically thin semiconductor for damage-free inflammation inhibition.

Inflammation, caused by accumulation of inflammatory cytokines from immunocytes, is prevalent in a variety of diseases. Electro-stimulation emerges as a promising candidate for inflammatory inhibition. Although electroacupuncture is free from surgical injury, it faces the challenges of imprecise pathways/current spikes, and insufficiently defined mechanisms, while non-optimal pathway or spike would require high current amplitude, which makes electro-stimulation usually accompanied by damage and complications. Here, we propose a neuromorphic electro-stimulation based on atomically thin semiconductor floating-gate memory interdigital circuit. Direct stimulation is achieved by wrapping sympathetic chain with flexible electrodes and floating-gate memory are programmable to fire bionic spikes, thus minimizing nerve damage. A substantial decrease (73.5%) in inflammatory cytokine IL-6 occurred, which also enabled better efficacy than commercial stimulator at record-low currents with damage-free to sympathetic neurons. Additionally, using transgenic mice, the anti-inflammation effect is determined by ß2 adrenergic signaling from myeloid cell lineage (monocytes/macrophages and granulocytes).

A flexible neural implant with ultrathin substrate for low-invasive brain-computer interface applications.

Implantable brain-computer interface (BCI) devices are an effective tool to decipher fundamental brain mechanisms and treat neural diseases. However, traditional neural implants with rigid or bulky cross-sections cause trauma and decrease the quality of the neuronal signal. Here, we propose a MEMS-fabricated flexible interface device for BCI applications. The microdevice with a thin film substrate can be readily reduced to submicron scale for low-invasive implantation. An elaborate silicon shuttle with an improved structure is designed to reliably implant the flexible device into brain tissue. The flexible substrate is temporarily bonded to the silicon shuttle by polyethylene glycol. On the flexible substrate, eight electrodes with different diameters are distributed evenly for local field potential and neural spike recording, both of which are modified by Pt-black to enhance the charge storage capacity and reduce the impedance. The mechanical and electrochemical characteristics of this interface were investigated in vitro. In vivo, the small cross-section of the device promises reduced trauma, and the neuronal signals can still be recorded one month after implantation, demonstrating the promise of this kind of flexible BCI device as a low-invasive tool for brain-computer communication.

Self-adaptive cardiac optogenetics device based on negative stretching-resistive strain sensor.

Precision medicine calls for high demand of continuous, closed-loop physiological monitoring and accurate control, especially for cardiovascular diseases. Cardiac optogenetics is promising for its superiority of cell selectivity and high time-space accuracy, but the efficacy of optogenetics relative to the input of light stimulus is detected and controlled separately by discrete instruments in vitro, which suffers from time retardation, energy consumption, and poor portability. Thus, a highly integrated system based on implantable sensors combining closed-loop self-monitoring with simultaneous treatment is highly desired. Here, we report a self-adaptive cardiac optogenetics system based on an original negative stretching-resistive strain sensor array for closed-loop heart rate recording and self-adaptive light intensity control. The strain sensor exhibits a dual and synchronous capability of precise monitor and physiological-electrical-optical regulation. In an in vivo ventricular tachycardia model, our system demonstrates the potential of a negative stretching-resistive device in controlling-in-sensor electronics for wearable/implantable autodiagnosis and telehealth applications.

A Novel Heterostructure Based on RuMo Nanoalloys and N-doped Carbon as an Efficient Electrocatalyst for the Hydrogen Evolution Reaction.

Heterostructures exhibit considerable potential in the field of energy conversion due to their excellent interfacial charge states in tuning the electronic properties of different components to promote catalytic activity. However, the rational preparation of heterostructures with highly active heterosurfaces remains a challenge because of the difficulty in component tuning, morphology control, and active site determination. Herein, a novel heterostructure based on a combination of RuMo nanoalloys and hexagonal N-doped carbon nanosheets is designed and synthesized. In this protocol, metal-containing anions and layered double hydroxides are employed to control the components and morphology of heterostructures, respectively. Accordingly, the as-made RuMo-nanoalloys-embedded hexagonal porous carbon nanosheets are promising for the hydrogen evolution reaction (HER), resulting in an extremely small overpotential (18 mV), an ultralow Tafel slope (25 mV dec-1 ), and a high turnover frequency (3.57 H2 s-1 ) in alkaline media, outperforming current Ru-based electrocatalysts. First-principle calculations based on typical 2D N-doped carbon/RuMo nanoalloys heterostructures demonstrate that introducing N and Mo atoms into C and Ru lattices, respectively, triggers electron accumulation/depletion regions at the heterosurface and consequently reduces the energy barrier for the HER. This work presents a convenient method for rational fabrication of carbon-metal heterostructures for highly efficient electrocatalysis.

Ionic Polyimide Derived Porous Carbon Nanosheets as High-Efficiency Oxygen Reduction Catalysts for Zn-Air Batteries.

Two-dimensional (2D) porous carbon nanosheets (2DPCs) have attracted great attention for their good porosity and long-distance conductivity. Factors such as templates, precursors, and carbonization-activation methods, directly determine their performance. However, rational design and preparation of porous carbon materials with controlled 2D morphology and heteroatom dopants remains a challenge. Therefore, an ionic polyimide with both sp2 - and sp3 -hybridized nitrogen atoms was prepared as a precursor for fabricating N-doped hexagonal porous carbon nanosheets through a hard-template approach. Because of the large surface area and efficient charge-mass transport, the resulting activated 2D porous carbon nanosheets (2DPCs-a) displayed promising electrocatalytic properties for oxygen reduction reaction (ORR) in alkaline and acidic media, such as ultralow half-wave potential (0.83 vs. 0.84 V of Pt/C) and superior limiting current density (5.42 vs. 5.14 mA cm-2 of Pt/C). As air cathodes in Zn-air batteries, the as-developed 2DPCs-a exhibited long stability and high capacity (up to 614 mA h g-1 ), which are both higher than those of commercial Pt/C. This work provides a convenient method for controllable and scalable 2DPCs fabrication as well as new opportunities to develop high-efficiency electrocatalysts for ORR and Zn-air batteries.