Seamless Interface Research Articles

The Medical Metaverse, Part 1: Introduction, Definitions, and New Horizons for Neuropsychiatry.

The Medical Metaverse, Part 1: Introduction, Definitions, and New Horizons for Neuropsychiatry.

Highly-Parallel Hardwired Deep Convolutional Neural Network for 1-ms Dual-Hand Tracking

1-ms vision systems represent an extreme case of temporal development in video sensing techniques. Moreover, a 1-ms dual-hand tracking system leverages the dexterous functionality of hands and thus serves as a seamless and intuitive interface for Human-Computer Interaction. Deep CNN is promising for high tracking robustness, however, neither GPU-based nor FPGA-based implementation addresses the tracking task with ultra-high-speed. This paper proposes: (a) A paradigm to directly map a deep CNN as a hardwired circuit, so the entire network runs in parallel and high processing speed is obtained. The network is exempted from memory access since all intermediate neural values are implicitly represented in hardware states. And condensed binarization is used to reduce resource utilization; (b) Hardware design of the hardwired network on FPGA, inside which kernel-adapted convolutional trees are devised to maximize the parallelism. The speed bottleneck of the network is therefore removed by implementing convolutional layers as fine-grained pipelines with unified components; (c) FPGA-GPU hetero complementation, which utilizes an auxiliary GPU network to compensate for accuracy of the FPGA network without affecting its speed. The quick primary results on FPGA are intermittently refined using delayed but accurate hints from GPU. Implementation results show that the proposed method reaches 973fps and consumes merely 1.30ms to process on <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$640\times 480$ </tex-math></inline-formula> images, while the accuracy is only 4.7% lower compared with the general method on test sequences. Video demonstrations are available at <uri xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">https://wcms.waseda.jp/em/5f9d020f136e7</uri> .

The Detector Control System of the New Small Wheel Electronics for the ATLAS experiment

The present ATLAS Small Wheel Muon detector is be replaced with a New Small Wheel(NSW) detector in order to cope up with the future LHC runs of high luminosit. One crucial part of the integration procedure concerns the validation of the electronics for a system with more than 2.1 M electronic channels. The readout chain is based on optical link technology connecting the back-end to the front-end electronics via the FELIX, which is a newly developed system that serves as the next generation readout driver for ATLAS. For the configuration, calibration and monitoring path the various electronics boards are supplied with the GBT-SCA ASIC and its purpose is to distribute control and monitoring signals to the electronics. Due to its complexity, NSW electronics requires the development of a sophisticated Control System. The use of such a system is necessary to allow the electronics to function consistently, safely and as a seamless interface to all sub-detectors and the technical infrastructure of the experiment. The central system handles the transition between the probe’s possible operating states while ensuring continuous monitoring and archiving of the system’s operating parameters.

MXene-Enabled Self-Adaptive Hydrogel Interface for Active Electroencephalogram Interactions.

Human-machine interaction plays a significant role in promoting convenience, production efficiency, and usage experience. Because of the universality and characteristics of electroencephalogram (EEG) signals, active EEG interaction is a promising and cutting-edge method for human-machine interaction. The seamless, skin-compliant, and motion-robust human-machine interface (HMI) for active EEG interaction has been in focus. Herein, we report a self-adaptive HMI (PAAS-MXene hydrogel) that can activate rapid gelation (5 s) using MXene cross-linking and conformably self-adapt to the scalp to help improve signal transduction. In addition to exhibiting satisfactory skin compliance, appropriate adhesion, and good biocompatibility, PAAS-MXene has demonstrated electrical performance reliability, such as low impedance (<50 Ω) at physiologically relevant frequencies, stable polarization potential (the rate of change is less than 6.5 × 10-4 V/min), negligible ion conductivity, and impedance change after 1000 stretch cycles, thereby realizing acquisition of EEG signals. In addition, a cap-free EEG signal acquisition method based on PAAS-MXene has been proposed. These findings confirm the high-precision detection ability of PAAS-MXene for electrocardiogram signals and EEG signals. Therefore, PAAS-MXene offers an option to actively control intention, motion, and vision through active EEG signals.

Hydrogel-Tissue Interface Interactions for Implantable Flexible Bioelectronics.

Hydrogels have emerged as multifunctional interface materials between implantable bioelectronic devices and biotissues. The soft and wet materials with low and alterable mechanical properties can match the mechanical, chemical, electrical, and biological properties of biotissues and thus diminish the mechanical and electrical mismatch. Interactions at the hydrogel-biotissue and hydrogel-device interfaces have attracted broad research interest. Great efforts have been devoted to establishing instant, strong, and conformal adhesion at the interface by chemical bonding, electrostatic interaction, hydrogen bonding, supramolecular recognition, hydrophobic association, and even topological entanglements at the interfaces. This Perspective provides a brief account of representative progress on the hydrogel-tissue adhesive that forms seamless and conformal interface adhesion and applications in implantable devices for physiological, cardiac, and neuronal signal collection and electrical stimulation. Major challenges such as wet adhesion and the stability of the adhesive hydrogel-tissue interface are identified for examination in future investigations.

Atomic transistors based on seamless lateral metal-semiconductor junctions with a sub-1-nm transfer length

The edge-to-edge connected metal-semiconductor junction (MSJ) for two-dimensional (2D) transistors has the potential to reduce the contact length while improving the performance of the devices. However, typical 2D materials are thermally and chemically unstable, which impedes the reproducible achievement of high-quality edge contacts. Here we present a scalable synthetic strategy to fabricate low-resistance edge contacts to atomic transistors using a thermally stable 2D metal, PtTe2. The use of PtTe2 as an epitaxial template enables the lateral growth of monolayer MoS2 to achieve a PtTe2-MoS2 MSJ with the thinnest possible, seamless atomic interface. The synthesized lateral heterojunction enables the reduced dimensions of Schottky barriers and enhanced carrier injection compared to counterparts composed of a vertical 3D metal contact. Furthermore, facile position-selected growth of PtTe2-MoS2 MSJ arrays using conventional lithography can facilitate the design of device layouts with high processability, while providing low contact resistivity and ultrashort transfer length on wafer scales.

Design, Characterization, and Dynamic Simulation of the MAHI Open Exoskeleton Upper Limb Robot

Stroke and spinal cord injury are becoming ever more prevalent in the United States. Recent research has shown that rehabilitation robots have the potential to positively impact the rehabilitation process by providing a platform for repetition-based movement therapy. To advance the field, future research directions for robotic rehabilitation are focused on advanced model-based control algorithms, and the combination of robotics with cutting-edge neuromodulation technologies. These approaches necessitate devices that not only feature kinematic and dynamic properties well-suited for model-based control, but also require devices that allow for easy placement of sensors and electrodes on the limb when inserted in the robot. With these design goals in mind, we present the MAHI Open Exoskeleton, a four-degree-of-freedom robot with an open mechanical structure and simplified dynamics, combined with open-source software, that together lay the groundwork for advanced model-based control. The dynamic properties of each joint were characterized and compared against other recently developed rehabilitation robots. Open-source software was developed for the robot, which provides users with both low-level and application-level interfaces to implement a variety of control strategies. Dynamic equations were developed and implemented into a real-time simulation with a visualization, including a seamless interface to the developed software library. Impedance control and model predictive control were implemented and compared to the simulation, proving the value of the new designs.

Multilayer polyetherimide films incorporating alumina nanolayers for dielectric capacitors

Multilayer dielectrics have attracted considerable attention in the last decade due to the enhanced electrical property and the promise for industry application. Thinner films with ultrahigh dielectric performance are yet to be designed. Herein, the ultrathin Al2O3 /PEI multilayer composite films are deliberately fabricated by combining the solution casting and atomic layer deposition techniques. The multilayer polymer constructed with 3-layer nano Al2O3 exhibits an ultrahigh breakdown strength (>800 kV/mm) and charge energy density (8.59 J/cm3) with high efficiency (93.8%). Counterintuitively, the hetero polyetherimide/alumina form a seamless interface revealed by a transmission electron microscope. The complementary molecular-dynamic calculation indicates the negative formation energy between the organic and inorganic interface to support the formation mechanism. Finite-element simulation reveals the reason for dielectric-breakdown enhancement from electrical field weakening and rapid heat dissipation assisted by the alumina layer. This ultrathin hetero multilayer composite strategy provides a pathway for the design and investigation of competitive heteropolymers and inorganics combinations.

Multi-cationic ionic liquid combination enabling 86-fold enhancement in frequency response and superior energy density in all-solid-state supercapacitors

Polymer ionic-conductor electrolytes with seamless electrode-electrolyte interface are indispensable for extracting the full potential of all-solid-state electrochemical double layer capacitors. While ionic liquids are among the best ionic conductors in liquid state and offer a wide potential window, translating their ionic mobility and activity to solid-state is important, yet challenging. In this direction, we report a mixed ionic liquid based solid electrolyte with an ionic conductivity of 1 mS/cm that delivers 86-fold higher scan-rate operability and 2.6 times lower relaxation time constant than their individual constituents. Specifically, a flexible polymeric matrix impregnated with a mixture of monocationic (1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl) imide (BMIm TFSI)) and a dicationic ionic liquid (1,4-di(vinylimidazolium) butane bisbromide ([DVIM]Br)) facilitates rapid and extensive formation of electrical double layer when integrated with carbon-based electrodes. The resulting all-solid-sate flexible supercapacitor achieves superior scan rate operability (15,000 mV/s) and ultralow relaxation time constant (7.8 ms), translating to high discharge current density (>1 mA/cm2), energy density (26.4 Wh/kg) and power density (61,127 W/kg). The improved rate capability (~83 %) and energy storage performance is attributed to a synergistic interplay of ionic strength, conductivity and ion mobility of the mixed ionic-liquid that unfold newer avenues towards solid-electrolyte engineering for energy storage devices.

Effects of neuronal cell adhesion molecule L1 and nanoparticle surface modification on microglia

Microelectrode arrays for neural recording suffer from low yield and stability partly due to the inflammatory host responses. A neuronal cell adhesion molecule L1 coating has been shown to promote electrode-neuron integration, reduce microglia activation and improve recording. Coupling L1 to surface via a nanoparticle (NP) base layer further increased the protein surface density and stability. However, the exact L1-microglia interaction in these coatings has not been studied. Here we cultured primary microglia on L1 modified surfaces (with and without NP) and characterized microglia activation upon phorbol myristate acetate (PMA) and lipopolysaccharide (LPS) stimulation. Results showed L1 coatings reduced microglia's superoxide production in response to PMA and presented intrinsic antioxidant properties. Meanwhile, L1 decreased iNOS, NO, and pro-inflammatory cytokines (TNF alpha, IL-6, IL-1 beta), while increased anti-inflammatory cytokines (TGF beta 1, IL-10) in LPS stimulated microglia. Furthermore, L1 increased Arg-1 expression and phagocytosis upon LPS stimulation. Rougher NP surface showed lower number of microglia attached per area than their smooth counterpart, lower IL-6 release and superoxide production, and higher intrinsic reducing potential. Finally, we examined the effect of L1 and nanoparticle modifications on microglia response in vivo over 8 weeks with 2-photon imaging. Microglial coverage on the implant surface was found to be lower on the L1 modified substrates relative to unmodified, consistent with the in vitro observation. Our results indicate L1 significantly reduces superoxide production and inflammatory response of microglia and promotes wound healing, while L1 immobilization via a nanoparticle base layer brings added benefit without adverse effects. Statement of significanceSurface modification of microelectrode arrays with L1 has been shown to reduce microglia coverage on neural probe surface in vivo and improves neural recording, but the specific mechanism of action is not fully understood. The results in this study show that surface bound L1 reduces superoxide production from cultured microglia via direct reduction reaction and signaling pathways, increases anti-inflammatory cytokine release and phagocytosis in response to PMA or LPS stimulation. Additionally, roughening the surface with nanoparticles prior to L1 immobilization further increased the benefit of L1 in reducing microglia activation and oxidative stress. Together, our findings shed light on the mechanisms of action of nanotextured and neuroadhesive neural implant coatings and guide future development of seamless tissue interface.

Ultrathin Van der Waals Antiferromagnet CrTe3 for Fabrication of In-Plane CrTe3 /CrTe2 Monolayer Magnetic Heterostructures.

Ultrathin van der Waals (vdW) magnets are heavily pursued for potential applications in developing high-density miniaturized electronic/spintronic devices as well as for topological physics in low-dimensional structures. Despite the rapid advances in ultrathin ferromagnetic vdW magnets, the antiferromagnetic counterparts, as well as the antiferromagnetic junctions, are much less studied owing to the difficulties in both material fabrication and magnetism characterization. Ultrathin CrTe3 layers have been theoretically proposed to be a vdW antiferromagnetic semiconductor with intrinsic intralayer antiferromagnetism. Herein, the epitaxial growth of monolayer (ML) and bilayer CrTe3 on graphite surface is demonstrated. The structure, electronic and magnetic properties of the ML CrTe3 are characterized by combining scanning tunneling microscopy/spectroscopy and non-contact atomic force microscopy and confirmed by density functional theory calculations. The CrTe3 MLs can be further utilized for the fabrication of a lateral heterojunction consisting of ML CrTe2 and ML CrTe3 with an atomically sharp and seamless interface. Since ML CrTe2 is a metallic vdW magnet, such a heterostructure presents the first in-plane magnetic metal-semiconductor heterojunction made of two vdW materials. The successful fabrication of ultrathin antiferromagnetic CrTe3 , as well as the magnetic heterojunction, will stimulate the development of miniaturized antiferromagnetic spintronic devices based on vdW materials.

Harnessing Oxidative Microenvironment for In Vivo Synthesis of Subcellular Conductive Polymer Microesicles Enhances Nerve Reconstruction.

Conductive polymers (CPs) are promising biomaterials to address signal connection at biointerfaces for tissue regeneration. However, regulating material microstructure at the subcellular scale to provide a more seamless interface between conductive substrates and cells remains a great challenge. Here, we demonstrate that chemical factors and enzyme-carried subcellular structures at lesion site provide a natural bioreactor to self-assemble conductive microvesicles (CMVs) for improving bioelectrical signal reconstruction. The synthesized CMVs contribute to the electrical conduction of the injured nerve in the early stage. Moreover, CMVs are eventually expelled via lymphatic capillary to minimize space-occupying and chronic inflammation. Therefore, we provide a prototype to integrate specific physiological microenvironments and polymer chemistry to manufacture subcellular functional materials with self-adaptive interface in vivo for biomedical applications.

A Self-Supporting, Conductor-Exposing, Stretchable, Ultrathin, and Recyclable Kirigami-Structured Liquid Metal Paper for Multifunctional E-Skin.

Electronic skin (E-skin) is a crucial seamless human-machine interface (HMI), holding promise in healthcare monitoring and personal electronics. Liquid metal (LM) has been recognized as an ideal electrode material to fabricate E-skins. However, conventional sealed LM electrodes cannot expose the LM layer for direct contact with the skin resulting in the low performance of electrophysiological monitoring. Furthermore, traditional printed LM electrodes are difficult to transfer or recycle, and fractures easily occur under stretching of the substrate. Here, we report a kind of LM electrode that we call a kirigami-structured LM paper (KLP), which is self-supporting, conductor-exposing, stretchable, ultrathin, and recyclable for multifunctional E-skin. The KLP is fabricated by the kirigami paper cutting art with three types of structures including uniaxial, biaxial, and square spiral. The KLP can act as an E-skin to acquire high-quality electrophysiological signals, such as electroencephalogram (EEG), electrocardiogram (ECG), and electromyogram (EMG). Upon integration with a triboelectric nanogenerator (TENG), the KLP can also operate as a self-powered E-skin. On the basis of the self-powered E-skin, we further developed a smart dialing communication system, which is applied on human skin to call a cellphone. Compared with conventional sealed or printed LM electrodes, the KLP can simultaneously achieve self-supporting, conductor-exposing, stretchable, ultrathin, and recyclable features. Such KLP offers potential for E-skins in healthcare monitoring and intelligent control, as well as smart robots, virtual reality, on-skin personal electronics, etc.

Highly stable flexible pressure sensors with a quasi-homogeneous composition and interlinked interfaces

Electronic skins (e-skins) are devices that can respond to mechanical stimuli and enable robots to perceive their surroundings. A great challenge for existing e-skins is that they may easily fail under extreme mechanical conditions due to their multilayered architecture with mechanical mismatch and weak adhesion between the interlayers. Here we report a flexible pressure sensor with tough interfaces enabled by two strategies: quasi-homogeneous composition that ensures mechanical match of interlayers, and interlinked microconed interface that results in a high interfacial toughness of 390 J·m−2. The tough interface endows the sensor with exceptional signal stability determined by performing 100,000 cycles of rubbing, and fixing the sensor on a car tread and driving 2.6 km on an asphalt road. The topological interlinks can be further extended to soft robot-sensor integration, enabling a seamless interface between the sensor and robot for highly stable sensing performance during manipulation tasks under complicated mechanical conditions.

Novel “Rubber” electrolyte will be applied to long-lasting, safer future EV batteries

Solid-state lithium metal batteries (LMBs) have become a potential component, as they provide a considerable safety upgrade by eliminating flammable organic solvents. Solid polymer electrolytes (SPEs) are also a promising candidate, owing to their non-toxicity, low-manufacturing cost, and comparatively soft nature that allows the development of a seamless interface with the electrodes. Polymerization-induced phase separation (PIPS) controls the connectivity of phase-separated structures and domain size, enabling the co-continuous nanostructures’ formation. Researchers of a study published in Nature envisioned that outstanding mechanical and ionic properties could be realized, provided ionic conducting materials form a 3D interconnected phase inside a mechanically strong elastomer matrix via PIPS.

Architecting Silk Protein and Melanin for Photoresponsive and Self‐Healable Optoelectronic Skins

AbstractThe central processes driving biological phenomena are based on the conduction of ions and electrons in biomaterials, implying the possibility of achieving a fully biomaterial‐based electronic skin. However, finding the appropriate biomaterials for electronic skins is still challenging. Here, a photoresponsive, self‐healable, and biomaterial‐based optoelectronic skin (OE‐skin) fabricated with melanin nanoparticles and silk protein is proposed and the electronic properties and their mechanisms in the artificially generated OE‐skin are reported. Not only does silk protein hydrogel provide a transparent and skin‐compatible platform for use as OE‐skin but it also provides the appropriate environment for melanin to demonstrate high electrical conductivity. The OE‐skin can be considered a p‐type semiconducting material showing high conductivity of up to 6 mS cm−1 in addition to a 40% enhancement in the conductivity by green laser and ultraviolet light emitting diode illuminations. Additionally, the OE‐skin autonomously heals itself from multiple cuts, allowing the restoration of its electrical properties. These material properties enable applications for strain‐sensors, humidity sensors, and ultraviolet light sensors, as well as image pixels to convert light‐lettering into electrical signals. The proposed fully biomaterial‐based OE material platform offers a new way for next‐generation electronic skins to achieve a seamless interface with the human body.

A Bilayer Electrolyte Design to Enable High-Areal-Capacity Composite Cathodes in Polymer Electrolytes Based Solid-State Lithium Metal Batteries

High-areal-capacity cathodes are needed for energy-dense solid-state batteries. Here, we demonstrate a bilayer polymer electrolyte design for cycling 3–6 mAh/cm2 NMC811 composite cathodes. The bilayer electrolyte comprises a cross-linked poly(ethylene oxide) (PEO)-based electrolyte layer and a linear-PEO-based electrolyte layer. The former provides dendritic resistance, and the latter provides a seamless interface with the cathode during cycling. Using a single layer of either membrane led to severe shorting or extremely low Coulombic efficiency (CE) in the first cycle. The general concept of a rigid dendrites-inhibiting electrolyte facing Li anode and a softer, cathode-integrated electrolyte that ensures contact with the cathodes during cycling may present a pattern for enabling high-energy-density cathodes.

Low-overpotential overall water splitting by a cooperative interface of cobalt-iron hydroxide and iron oxyhydroxide

Interface engineering is a powerful strategy for modulating electronic structure and enhancing intrinsic activity of electrocatalysts for water splitting. Here, we grow two-dimensional cobalt-iron hydroxide (CoFe-OH) nanosheets on nickel foam substrates and deposit FeOOH nanoparticles in a rapid and scalable wet chemical approach. The [email protected] nanocomposite features abundant active sites and high surface area, allowing fast kinetics for electrochemical water splitting. The electrode has a low overpotential value of 200 mV at 50 mA cm−2 for oxygen evolution. When used as both anode and cathode for overall water splitting, [email protected] provides a low cell voltage of 1.56 V to deliver 10 mA cm−2 current density. The synergistic activity is presumed to be from the seamless interface of CoFe-OH and FeOOH, improving conductivity and mass transfer. We envision that this simple approach may offer a new direction for designing efficient electrodes for energy conversion applications.

Continuously growing multi-layered hydrogel structures with seamless interlocked interface

<h2>Summary</h2> Many natural tissues feature layered structures for multi-functionality as each layer consists of different cell types and therefore exhibits unique physicochemical properties. Creating such complex multi-layered structures in human-made soft materials is hardly achievable with common gelation methods, lacking spatiotemporal control, and thus demands a living polymerization-based controllable continuous growing process to imitate bio-tissue growth. Herein, a method, namely, ultraviolet-triggered surface catalytically initiated radical polymerization (UV-SCIRP), is demonstrated in living growth of uniform hydrogel layers at room temperature, facilitated by the <i>in situ</i> generation of Fe²⁺ ion catalysts from the surface-bound Fe³⁺ ions of the hydrogel substrate. Reiterative application of UV-SCIRP enables fabrication of multi-layered hydrogels with diverse components and layered features. The surface-catalyzed gelation makes the method effective in constructing complex hydrogel patterns, non-flat arbitrary-shaped hydrogel objects, and blood vessel-like intricate multi-layered hydrogel tubes. This work manifests a new route to engineer bioinspired structural hydrogels and complex soft architectures with on-demand functions.

Graphene-Based Scaffolds: Fundamentals and Applications for Cardiovascular Tissue Engineering.

Cardiac tissue engineering requires materials that can faithfully recapitulate and support the native in vivo microenvironment while providing a seamless bioelectronic interface. Current limitations of cell scaffolds include the lack of electrical conductivity and suboptimal mechanical properties. Here we discuss how the incorporation of graphene into cellular scaffolds, either alone or in combination with other materials, can affect morphology, function, and maturation of cardiac cells. We conclude that graphene-based scaffolds hold great promise for cardiac tissue engineering.