architecture, diversity, and electrophysiology of the human brain at early stages. [7,8] Brain organoids thus provide a reliable and easily accessible platform to study human brain development and neurodevelopmental diseases, [9][10][11][12] bridging the gap between animal research and human clinical study.However, long-term stable recording of single-cell electrophysiology in developing brain organoids is still a challenge. The recording technology not only needs to form minimally invasive and long-term stable electrical interfaces with individual neurons 3D distributed across brain organoids but also needs to accommodate the rapid volume change occurring during the organoid organogenesis and cortical expansion. Optical imaging coupled with fluorescence dyes [13] or calcium indicators [14] has been used to visualize the neuron activities in 3D. They, however, are limited by temporal resolution, penetration depth, and long-term signal stability. Electrical measurement techniques such as 2D multielectrode arrays (MEA) [15,16] and patch-clamp [17,18] have been applied to measure the functional development of brain organoids, but they can only capture the activities from the bottom surface of brain organoids [1,19,20] or assay one cell at a time with cell membrane disruption. The recent development of 3D bioelectronics enables 3D interfaces with brain organoids. [21][22][23][24][25][26][27] However, they either only contact organoids at the surface by flexible electronics, [21][22][23] where noncorrelated and 3D-distributed single-unit action potentials cannot be recorded, or penetrate organoids invasively by rigid probes, [25] which cannot further accommodate volume and morphological changes of brain organoids during development. It has also been shown that organoids can grow around a suspended array of electrodes, [26,27] but the electrodes cannot deform to adapt to the morphological changes of the organoid. To date, it is still a challenge to noninvasively probe neuron activity at single-cell, single-spike spatiotemporal resolution across the 3D volume of brain organoids, and over the time course of development. This constraint prevents further understanding of the functional development in brain organoids and standardizing culture conditions and protocols for brain organoid generation based on their electrical functions.Recently, we developed a cyborg organoid platform by integrating "tissue-like" stretchable mesh nanoelectronics with 2D stem cell sheets. Leveraging the 2D-to-3D reconfiguration Human induced pluripotent stem cell derived brain organoids have shown great potential for studies of human brain development and neurological disorders. However, quantifying the evolution of the electrical properties of brain organoids during development is currently limited by the measurement techniques, which cannot provide long-term stable 3D bioelectrical interfaces with developing brain organoids. Here, a cyborg brain organoid platform is reported, in which "tissue-like" stretchable mesh nanoelectronics are designed...

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The cyborg brain organoid platform reported by Jia Liu and co-workers in article number 2106829 features "tissue-like" stretchable mesh nanoelectronics designed to match the mechanical properties of brain organoids and to be folded by the organogenetic process of progenitor or stem cells. Long-term stable, continuous recording is enabled and the emergence of single-cell action potentials from early-stage brain organoid development can be captured. A 3D reconstructed fluorescence image of cyborg brain organoid tissue is shown. The red represents neural stem cells, the green neurons, the blue cell nuclei, and the yellow soft nanoelectronic interconnects and sensors.

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Human induced pluripotent stem cell-derived brain organoids have shown great potential for studies of human brain development and neurological disorders. However, quantifying the evolution and development of electrical functions in brain organoids is currently limited by measurement techniques that cannot provide long-term stable three-dimensional (3D) bioelectrical interfaces with brain organoids during development. Here, we report a cyborg brain organoid platform, in which 2D progenitor or stem cell sheets can fold "tissue-like" stretchable mesh nanoelectronics through organogenesis, distributing stretchable electrode arrays across 3D organoids. The tissue-wide integrated stretchable electrode arrays show no interruption to neuronal differentiation, adapt to the volume and morphological changes during organogenesis, and provide long-term stable electrical contacts with neurons within brain organoids during development. The seamless and non-invasive coupling of electrodes to neurons enables a 6-month continuous recording of the same brain organoids and captures the emergence of single-cell action potentials from early-stage brain organoid development.

Two-dimensional (2D) polar materials experience an in-plane charge transfer between different elements due to their electron negativities. When they form vertical heterostructures, the electrostatic force triggered by such charge transfer plays an important role in the interlayer bonding beyond van der Waals (vdW) interaction. Our comprehensive first principle study on the structural stability of the 2D SiC/GeC hybrid bilayer heterostructure has found that the electrostatic interlayer interaction can induce the π-π orbital hybridization between adjacent layers under different stacking and out-of-plane species ordering, with strong hybridization in the cases of Si-C and C-Ge species orderings but weak hybridization in the case of the C-C ordering. In particular, the attractive electrostatic interlayer interaction in the cases of Si-C and C-Ge species orderings mainly controls the equilibrium interlayer distance and the vdW interaction makes the system attain a lower binding energy. On the contrary, the vdW interaction mostly controls the equilibrium interlayer distance in the case of the C-C species ordering and the repulsive electrostatic interlayer force has less effect. Interesting finding is that the band structure of the SiC/GeC hybrid bilayer is sensitive to the layer-layer stacking and the out-of-plane species ordering. An indirect band gap of 2.76 eV (or 2.48 eV) was found under the AA stacking with Si-C ordering (or under the AB stacking with C-C ordering). While a direct band gap of 2.00 eV – 2.88 eV was found under other stacking and species orderings, demonstrating its band gap tunable feature. Furthermore, there is a charge redistribution in the interfacial region leading to a built-in electric field. Such field will separate the photo-generated charge carriers in different layers and is expected to reduce the probability of carrier recombination, and eventually give rise to the electron tunneling between layers.

Face mask usage is a critical means of limiting SARS-CoV-2 airborne transmission. To the best of our knowledge, a single study reviewing all major life stages of a mask has yet to be conducted. Here, we first describe the production and material sourcing of respirators, surgical/procedural masks, and cloth masks. We then evaluate filtration efficiency, fit, and breathability in estimating emitted viral load and personal compliance. In decontamination, vaporous hydrogen peroxide and ultraviolet germicidal irradiation are feasible and effective methods for large healthcare systems, while washing is recommended for masks with no electrostatic charge (e.g., cotton masks). Finally, we discuss how disposal of masks only contributes marginally to current environmental issues. Insights into the life cycle stages of masks may inform mask use and support mitigation strategies in preventing the spread of respiratory diseases.

Two-dimensional (2D) lateral polar heterostructures, constructed by seamlessly stitching 2D polar materials, exhibit unique properties triggered by the in-plane charge transfer between different elements in each domain. Our first-principles study of 2D SiC/GeC lateral polar heterostructures has unraveled their interesting characteristics. The local strain induced by a lattice mismatch leads to an artificial uniaxial strain along the interface. The synergistic effect of such uniaxial strain, the microstructure of interface, and the width of domains modulates the feature of the bandgap with an indirect bandgap nature in armchair lateral heterostructures and a direct bandgap nature in zigzag lateral heterostructures. The bandgap monotonically decreases with increasing the width of domains, showing its tunability. Furthermore, the valence band maximum is found to be mainly contributed from C-2 p orbitals located at both GeC and SiC domains, and the conduction band minimum is mainly contributed from Ge-4 p orbitals located at the GeC domain, implying that most excited electrons prefer to stay at the GeC domain of the SiC/GeC lateral polar heterostructures. Interestingly, a net charge transfer from the SiC domain to the GeC domain was found, resulting in a spontaneous lateral p–n junction, and there is a net charge redistribution at the interfacial region leading to a built-in electric field which is expected to reduce the carrier recombination losses, implying the promising application for visible light photocatalyst, photovoltaics, and water splitting to achieve clean and renewable energy.