A bioinspired optoelectronically engineered artificial neurorobotics device with sensorimotor functionalities

Development of the next generation of bio- and nano-electronics is inseparably connected to the innovative concept of emulation and reproduction of biological sensorimotor systems and artificial neurobotics. Here, we report for the first time principally new artificial bioinspired optoelectronic sensorimotor system for the controlable immitation of opto-genetically engineered neurons in the biological motor system. The device is based on inorganic optical synapse (In-doped TiO2 nanofilm) assembled into a liquid metal (galinstan) actuator. The optoelectronic synapse generates polarised excitatory and inhibitory postsynaptic potentials to trigger the liquid metal droplet to vibrate and then mimic the expansion and contraction of biological fibre muscle. The low-energy consumption and precise modulation of electrical and mechanical outputs are the distinguished characteristics of fabricated sensorimotor system. This work is the underlying significant step towards the development of next generation of low-energy the internet of things for bioinspired neurorobotic and bioelectronic system

Nanoscale Au-ZnO heterostructure developed by atomic layer deposition towards amperometric H2O2 detection

Nanoscale Au-ZnO heterostructures were fabricated on 4-in. SiO2/Si wafers by the atomic layer deposition (ALD) technique. Developed Au-ZnO heterostructures after post-deposition annealing at 250 degrees C were tested for amperometric hydrogen peroxide (H2O2) detection. The surface morphology and nanostructure of Au-ZnO heterostructures were examined by field emission scanning electron microscopy (FE-SEM), Raman spectroscopy, atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), etc. Additionally, the electrochemical behavior of Au-ZnO heterostructures towards H2O2 sensing under various conditions is assessed by chronoamperometry and electrochemical impedance spectroscopy (EIS). The results showed that ALD-fabricated Au-ZnO heterostructures exhibited one of the highest sensitivities of 0.53 mu A mu M(-1)cm(-2), the widest linear H2O2 detection range of 1.0 mu M-120mM, a low limit of detection (LOD) of 0.78 mu M, excellent selectivity under the normal operation conditions, and great long-term stability. Utilization of the ALD deposition method opens up a unique opportunity for the improvement of the various capabilities of the devices based on Au-ZnO heterostructures for amperometric detection of different chemicals

Nanoscale all-oxide-heterostructured bio-inspired optoresponsive nociceptor

Retina nociceptor, as a key sensory receptor, not only enables the transport of warning signals to the human central nervous system upon its exposure to noxious stimuli, but also triggers the motor response that minimizes potential sensitization. In this study, the capability of two-dimensional all-oxide-heterostructured artificial nociceptor as a single device with tunable properties was confirmed. Newly designed nociceptors utilize ultra-thin sub-stoichiometric TiO2-Ga2O3 heterostructures, where the thermally annealed Ga2O3 films play the role of charge transfer controlling component. It is discovered that the phase transformation in Ga2O3 is accompanied by substantial jump in conductivity, induced by thermally assisted internal redox reaction of Ga2O3 nanostructure during annealing. It is also experimentally confirmed that the charge transfer in all-oxide heterostructures can be tuned and controlled by the heterointerfaces manipulation. Results demonstrate that the engineering of heterointerfaces of two-dimensional (2D) films enables the fabrication of either high-sensitive TiO2-Ga2O3 (Ar) or high-threshold TiO2-Ga2O3 (N-2) nociceptors. The hypersensitive nociceptor mimics the functionalities of corneal nociceptors of human eye, whereas the delayed reaction of nociceptor is similar to high-threshold nociceptive characteristics of human sensory system. The long-term stability of 2D nociceptors demonstrates the capability of heterointerfaces engineering for effective control of charge transfer at 2D heterostructured devices

Optoelectronic nociceptive sensors based on heterostructured semiconductor films

A visible light optical nociceptive sensor was developed based on the heterostructured plasmonic Au/G2O3/TiO2 semiconductor films. The incorporation of nitrogen atoms and the following phase transformation of G2O3 ultra-thin film during rapid thermal annealing enabled the nociceptive characteristics in heterostructured G2O3/TiO2 plasmonic visible light sensor. The fabricated nociceptor showed the post-synaptic current, nociceptive threshold and non-adaption modes in normal states

Macrocyclic cyanocobalamin (vitamin B12) as a homogeneous electrocatalyst for water oxidation under neutral conditions

Highly water-soluble cyanocobalamin (also known as vitamin B-12) is the most structurally macrocyclic complex comprising cobalt in the center of a corrin ring. Interestingly, it acts as a robust electrocatalyst in water oxidation at similar to 0.58 V overpotential with a faradaic efficiency of 97.50% under neutral buffered conditions. The catalyst is impressively stable even after long-term bulk electrolysis, and homogeneous in nature, as established by a series of experiments and characterization techniques

Metal/semiconductor hetero-interface engineering for photocurrent controlling in plasmonic photodetectors

The heterointerface engineering at metal/semiconductor (MS) hetero-interfaces in Au/Ga2O3/TiO2 plasmonic photosensors enabled the modulation of charge transfer and photoconductance of detectors for adaptive perception of visible optical lights. The photoconductance at heterointerface between plasmonic Au antenna and main TiO2 semiconductor was modulated by deposition of ultra-thin Ga2O3 film at the Au/TiO2 hetero-interface. The fast and improved photoresponsivity were achieved by the surface functionalization of Au plasmonic antenna with N2 doped Ga2O3 ultra-thin film

Selective cyclodimerization of epichlorohydrin to dioxane derivatives over MOFs

Glycerol can be converted to valuable products such as epichlorohydrin which is an important intermediate applied in various industries. For example, dioxane derivatives, which are important pharmaceuticals, can be obtained from epichlorohydrin. In the present study, ZIF-8, ZIF-67, MIL-100, and UiO-66 were applied for the direct cyclodimerization of epichlorohydrin. These MOFs were selected because they were already applied as active catalysts in ring opening of epoxides. Among them, ZIF-8 showed the highest activity and selectivity in the absence of any solvent or co-catalyst. Using ZIF-8 as a catalyst, the cyclodimer product (1,4-dioxane 2,5-bis-chloromethyl) was obtained in a yield of about 70% which was significantly superior to previous homo or heterogeneous catalysts for this reaction. Due to ZIF-8 structure and the proposed mechanism, the cyclodimerization reaction catalyzed either by the defects in the structure and/or on the surface. Furthermore, acidic-basic characteristics were also in play. The NH3 and CO2 temperature-programed desorption technique were utilized to identify the active sites and thereby reaction mechanism. Moreover, because of similar properties of ZIF-8 to zeolites, the activity of commercial ZSM-5 for the same reaction was also investigated in this work

2D semiconductor nanomaterials and heterostructures : controlled synthesis and functional applications

Two-dimensional (2D) semiconductors beyond graphene represent the thinnest stable known nanomaterials. Rapid growth of their family and applications during the last decade of the twenty-first century have brought unprecedented opportunities to the advanced nano- and opto-electronic technologies. In this article, we review the latest progress in findings on the developed 2D nanomaterials. Advanced synthesis techniques of these 2D nanomaterials and heterostructures were summarized and their novel applications were discussed. The fabrication techniques include the state-of-the-art developments of the vapor-phase-based deposition methods and novel van der Waals (vdW) exfoliation approaches for fabrication both amorphous and crystalline 2D nanomaterials with a particular focus on the chemical vapor deposition (CVD), atomic layer deposition (ALD) of 2D semiconductors and their heterostructures as well as on vdW exfoliation of 2D surface oxide films of liquid metals