Battery-free, lightweight, injectable microsystem for in vivo wireless pharmacology and optogenetics.

Pharmacology and optogenetics are widely used in neuroscience research to study the central and peripheral nervous systems. While both approaches allow for sophisticated studies of neural circuitry, continued advances are, in part, hampered by technology limitations associated with requirements for physical tethers that connect external equipment to rigid probes inserted into delicate regions of the brain. The results can lead to tissue damage and alterations in behavioral tasks and natural movements, with additional difficulties in use for studies that involve social interactions and/or motions in complex 3-dimensional environments. These disadvantages are particularly pronounced in research that demands combined optogenetic and pharmacological functions in a single experiment. Here, we present a lightweight, wireless, battery-free injectable microsystem that combines soft microfluidic and microscale inorganic light-emitting diode probes for programmable pharmacology and optogenetics, designed to offer the features of drug refillability and adjustable flow rates, together with programmable control over the temporal profiles. The technology has potential for large-scale manufacturing and broad distribution to the neuroscience community, with capabilities in targeting specific neuronal populations in freely moving animals. In addition, the same platform can easily be adapted for a wide range of other types of passive or active electronic functions, including electrical stimulation.

Publisher Correction: Large-area MRI-compatible epidermal electronic interfaces for prosthetic control and cognitive monitoring.

In Fig. 4c of this Article, the scale bar units were incorrectly stated as 'µV'; the correct units are 'mV'. The figure has now been amended accordingly.

Large-area MRI-compatible epidermal electronic interfaces for prosthetic control and cognitive monitoring.

Skin-interfaced medical devices are critically important for diagnosing disease, monitoring physiological health and establishing control interfaces with prosthetics, computer systems and wearable robotic devices. Skin-like epidermal electronic technologies can support these use cases in soft and ultrathin materials that conformally interface with the skin in a manner that is mechanically and thermally imperceptible. Nevertheless, schemes so far have limited the overall sizes of these devices to less than a few square centimetres. Here, we present materials, device structures, handling and mounting methods, and manufacturing approaches that enable epidermal electronic interfaces that are orders of magnitude larger than previously realized. As a proof-of-concept, we demonstrate devices for electrophysiological recordings that enable coverage of the full scalp and the full circumference of the forearm. Filamentary conductive architectures in open-network designs minimize radio frequency-induced eddy currents, forming the basis for structural and functional compatibility with magnetic resonance imaging. We demonstrate the use of the large-area interfaces for the multifunctional control of a transhumeral prosthesis by patients who have undergone targeted muscle-reinnervation surgery, in long-term electroencephalography, and in simultaneous electroencephalography and structural and functional magnetic resonance imaging.

High Volumetric and Gravimetric Capacity Electrodeposited Mesostructured Sb2 O3 Sodium Ion Battery Anodes.

Sodium ion batteries (SIBs) are considered promising alternatives to lithium ion batteries for grid-scale and other energy storage applications because of the broad geographical distribution and low cost of sodium relative to lithium. Here, fabrication and characterization of high gravimetric and volumetric capacity 3D Ni-supported Sb2 O3 anodes for SIBs are presented. The electrodes are prepared by colloidal templating and pulsed electrodeposition followed by heat treatment. The colloidal template is optimized to provide large pore interconnects in the 3D scaffold to enable a high active materials loading and accommodate a large volume expansion during cycling. An electrodeposited loading of 1.1 g cm-3 is chosen to enable a combined high gravimetric and volumetric capacity. At this loading, the electrodes exhibit a specific capacity of ≈445 mA h g-1 and a volumetric capacity of ≈488 mA h cm-3 with a capacity retention of 89% after 200 cycles at 200 mA g-1 . The stable cycling performance can be attributed to the 3D metal scaffold, which supports active materials undergoing large volume changes, and an initial heat treatment appears to improve the adhesion of the Sb2 O3 to the metal scaffold.

Publisher Correction: Large-area MRI-compatible epidermal electronic interfaces for prosthetic control and cognitive monitoring.

In Fig. 4c of this Article originally published, the bottom y axis was incorrectly labelled as 'MRI-ECG (µV)'; the correct label is 'MRI/ECG'. In addition, in Fig. 4d, the bottom y axis was incorrectly labelled as 'ECG (µV)'; the correct label is 'ECG (mV)'. The scale bar units were also incorrectly stated as 'mV', the correct units are 'µV'. The figure has now been amended accordingly.

Colloidal Metal-Organic Framework Hexapods Prepared from Postsynthesis Etching with Enhanced Catalytic Activity and Rollable Packing.

Recent studies on the effect of particle shapes have led to extensive applications of anisotropic colloids as complex materials building blocks. Although much research has been devoted to colloids of convex polyhedral shapes, branched colloids remain largely underexplored because of limited synthesis strategies. Here we achieved the preparation of metal-organic framework (MOF) colloids in a hexapod shape, not directly from growth but from postsynthesis etching of truncated rhombic dodecahedron (TRD) parent particles. To understand the branch development, we used in situ optical microscopy to track the local surface curvature evolution of the colloids as well as facet-dependent etching rate. The hexapods show unique properties, such as improved catalytic activity in a model Knoevenagel reaction likely due to enhanced access to active sites, and the assembly into open structures which can be easily integrated with a self-rolled-up nanomembrane structure. Both the postsynthesis etching and the hexapod colloids demonstrated here show a new route of engineering micrometer-sized building blocks with exotic shapes and intrinsic functionalities originated from the molecular structure of materials.

Dendritic nanostructured FeS2-based high stability and capacity Li-ion cathodes.

Here we show that dendritic architectures are attractive as the basis of hierarchically structured battery electrodes. Dendritically structured FeS2, synthesized via simple thermal sulfidation of electrodeposited dendritic α-Fe, was formed into an electrode and cycled vs. lithium. The reversible capacities of the dendritic FeS2 cathode were 560 mA h g-1 at 0.5C and 533 mA h g-1 at 1.0C after 50 cycles over 0.7-3.0 V. Over 0.7-2.4 V, where the electrode is more stable, the reversible capacities are 348 mA h g-1 at 0.2C and 179 mA h g-1 at 1.0C after 150 cycles. The good cycling performance and high specific capacities of the dendritic FeS2 cathodes are attributed to the ability of a dendritic structure to provide good ion and electron conducting pathways, and a large surface area. Importantly, the dendritic structure appears capable of accommodating volume changes imposed by the lithiation and delithiation process. The presence of a Li2-x FeS2 phase is indicated for the first time by high-resolution transmission electron microscopy (HRTEM) and scanning transmission electron microscopy (STEM) electron energy loss spectroscopy (EELS). We suspect this phase is what enables electrochemical cycling to possess high reversibility over 0.7-2.4 V.