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Myocardial infarction (MI) is one of the leading causes of death and disability. Recently developed cardiac patches provide mechanical support and additional conductive paths to promote electrical signal propagation in the MI area to synchronize cardiac excitation and contraction. Cardiac patches based on conductive polymers offer attractive features; however, the modest levels of elasticity and high impedance interfaces limit their mechanical and electrical performance. These structures also operate as permanent implants, even in cases where their utility is limited to the healing period of tissue damaged by the MI. The work presented here introduces a highly conductive cardiac patch that combines bioresorbable metals and polymers together in a hybrid material structure configured in a thin serpentine geometry that yields elastic mechanical properties. Finite element analysis guides optimized choices of layouts in these systems. Regular and synchronous contraction of human induced pluripotent stem cell‐derived cardiomyocytes on the cardiac patch and ex vivo studies offer insights into the essential properties and the bio‐interface. These results provide additional options in the design of cardiac patches to treat MI and other cardiac disorders. [ABSTRACT FROM AUTHOR]

Bioengineering approaches that combine living cellular components with three-dimensional scaffolds to generate motion can be used to develop a new generation of miniature robots. Integrating on-board electronics and remote control in these biological machines will enable various applications across engineering, biology, and medicine. Here, we present hybrid bioelectronic robots equipped with battery-free and microinorganic light-emitting diodes for wireless control and real-time communication. Centimeter-scale walking robots were computationally designed and optimized to host on-board optoelectronics with independent stimulation of multiple optogenetic skeletal muscles, achieving remote command of walking, turning, plowing, and transport functions both at individual and collective levels. This work paves the way toward a class of biohybrid machines able to combine biological actuation and sensing with on-board computing. [ABSTRACT FROM AUTHOR]

Elastomeric encapsulation layers are widely used in soft, wearable devices to physically isolate rigid electronic components from external environmental stimuli (e.g., stress) and facilitate device sterilization for reusability. In devices experiencing large deformations, the stress-isolation effect of the top encapsulation layer can eliminate the damage to the electronic components caused by external forces. However, for health monitoring and sensing applications, the strain-isolation effect of the bottom encapsulation layer can partially block the physiological signals of interest and degrade the measurement accuracy. Here, an analytic model is developed for the strain- and stress-isolation effects present in wearable devices with elastomeric encapsulation layers. The soft, elastomeric encapsulation layers and main electronic components layer are modeled as transversely isotropic-elastic mediums and the strain- and stress-isolation effects are described using isolation indexes. The analysis and results show that the isolation effects strongly depend on the thickness, density, and elastic modulus of both the elastomeric encapsulation layers and the main electronic component layer. These findings, combined with the flexible mechanics design strategies of wearable devices, provide new design guidelines for future wearable devices to protect them from external forces while capturing the relevant physiological signals underneath the skin. [ABSTRACT FROM AUTHOR]

With the high flexibility, good conformability and lightweight, the next‐generation energy harvesters could exist in the format of epidermal electronics. They are able to convert the mechanical energy from daily body motions into electrical signals for energy harvesting and human‐machine interfaces. Triboelectric nanogenerators (TENGs) have proven to be excellent candidates for wearable energy harvesters, however, the reported TENGs commonly face the hurdles of poor adhesion to skin and relative thick in geometry up to several cm. Herein, a series of ultrathin, soft, tattoo‐like triboelectric nanogenerators (TL‐TENGs) with well‐designed aesthetic patterns are introduced. With the ultrathin materials applied and state of art processing techniques in epidermal electronics, the TL‐TENGs present an outstanding mechanical property of high robustness and thickness of tens of μm. Besides, TL‐TENGs own remarkable electrical characteristics, the open‐circuit voltage and short circuit current can reach up to ≈180 V and ≈2.2 μA under constant tapping (≈16 kPa), respectively. With the well structural mechanics designs, the TL‐TENGs can be customized into various tattoo patterns, such as twelve Chinese zodiac signs. Demonstrations of TL‐TENGs in energy harvesting and the human‐machine interface indicate great potential in next generation wearable nanogenerators and internet of things. [ABSTRACT FROM AUTHOR]

Skin-integrated electronics, also known as electronic skin (e-skin), are rapidly developing and are gradually being adopted in biomedical fields as well as in our daily lives. E-skin capable of providing sensitive and high-resolution tactile sensations and haptic feedback to the human body would open a new e-skin paradigm for closed-loop human–machine interfaces. Here, we report a class of materials and mechanical designs for the miniaturization of mechanical actuators and strategies for their integration into thin, soft e-skin for haptic interfaces. The mechanical actuators exhibit small dimensions of 5 mm diameter and 1.45 mm thickness and work in an electromagnetically driven vibrotactile mode with resonance frequency overlapping the most sensitive frequency of human skin. Nine mini actuators can be integrated simultaneously in a small area of 2 cm × 2 cm to form a 3 × 3 haptic feedback array, which is small and compact enough to mount on a thumb tip. Furthermore, the thin, soft haptic interface exhibits good mechanical properties that work properly during stretching, bending, and twisting and therefore can conformally fit onto various parts of the human body to afford programmable tactile enhancement and Braille recognition with an accuracy rate over 85%. [ABSTRACT FROM AUTHOR]

Temporary cardiac pacemakers used in periods of need during surgical recovery involve percutaneous leads and externalized hardware that carry risks of infection, constrain patient mobility and may damage the heart during lead removal. Here we report a leadless, battery-free, fully implantable cardiac pacemaker for postoperative control of cardiac rate and rhythm that undergoes complete dissolution and clearance by natural biological processes after a defined operating timeframe. We show that these devices provide effective pacing of hearts of various sizes in mouse, rat, rabbit, canine and human cardiac models, with tailored geometries and operation timescales, powered by wireless energy transfer. This approach overcomes key disadvantages of traditional temporary pacing devices and may serve as the basis for the next generation of postoperative temporary pacing technology. A biodegradable pacemaker without external leads improves the safety of temporary cardiac pacing. [ABSTRACT FROM AUTHOR]

Large, distributed collections of miniaturized, wireless electronic devices1,2 may form the basis of future systems for environmental monitoring3, population surveillance4, disease management5 and other applications that demand coverage over expansive spatial scales. Aerial schemes to distribute the components for such networks are required, and—inspired by wind-dispersed seeds6—we examined passive structures designed for controlled, unpowered flight across natural environments or city settings. Techniques in mechanically guided assembly of three-dimensional (3D) mesostructures7–9 provide access to miniature, 3D fliers optimized for such purposes, in processes that align with the most sophisticated production techniques for electronic, optoelectronic, microfluidic and microelectromechanical technologies. Here we demonstrate a range of 3D macro-, meso- and microscale fliers produced in this manner, including those that incorporate active electronic and colorimetric payloads. Analytical, computational and experimental studies of the aerodynamics of high-performance structures of this type establish a set of fundamental considerations in bio-inspired design, with a focus on 3D fliers that exhibit controlled rotational kinematics and low terminal velocities. An approach that represents these complex 3D structures as discrete numbers of blades captures the essential physics in simple, analytical scaling forms, validated by computational and experimental results. Battery-free, wireless devices and colorimetric sensors for environmental measurements provide simple examples of a wide spectrum of applications of these unusual concepts.With a design inspired by wind-dispersed seeds, a series of three-dimensional passive fliers at the macro-, meso- and microscale are realized that can bear active electronic payloads. [ABSTRACT FROM AUTHOR]

Capabilities for continuous monitoring of pressures and temperatures at critical skin interfaces can help to guide care strategies that minimize the potential for pressure injuries in hospitalized patients or in individuals confined to the bed. This paper introduces a soft, skin-mountable class of sensor system for this purpose. The design includes a pressure-responsive element based on membrane deflection and a battery-free, wireless mode of operation capable of multi-site measurements at strategic locations across the body. Such devices yield continuous, simultaneous readings of pressure and temperature in a sequential readout scheme from a pair of primary antennas mounted under the bedding and connected to a wireless reader and a multiplexer located at the bedside. Experimental evaluation of the sensor and the complete system includes benchtop measurements and numerical simulations of the key features. Clinical trials involving two hemiplegic patients and a tetraplegic patient demonstrate the feasibility, functionality and long-term stability of this technology in operating hospital settings. Uninterrupted monitoring of pressure and temperature at skin interfaces can help to minimize the potential for pressure injuries in hospitalized or bedridden patients. Here, the authors introduce a soft, skin-mountable sensor that can continuously provide readings via antennas mounted under bedding, and demonstrate the functionality and robustness of the devices on patients. [ABSTRACT FROM AUTHOR]

Injured peripheral nerves typically exhibit unsatisfactory and incomplete functional outcomes, and there are no clinically approved therapies for improving regeneration. Post‐operative electrical stimulation (ES) increases axon regrowth, but practical challenges, from the cost of extended operating room time to the risks and pitfalls associated with transcutaneous wire placement, have prevented broad clinical adoption. This study presents a possible solution in the form of advanced bioresorbable materials for a type of thin, flexible, wireless implant that provides precisely controlled ES of the injured nerve for a brief time in the immediate post‐operative period. Afterward, rapid, complete, and safe modes of bioresorption naturally and quickly eliminate all of the constituent materials in their entirety, without the need for surgical extraction. The unusually high rate of bioresorption follows from the use of a unique, bilayer enclosure that combines two distinct formulations of a biocompatible form of polyanhydride as an encapsulating structure, to accelerate the resorption of active components and confine fragments until complete resorption. Results from mouse models of tibial nerve transection with re‐anastomosis indicate that this system offers levels of performance and efficacy that match those of conventional wired stimulators, but without the need to extend the operative period or to extract the device hardware. [ABSTRACT FROM AUTHOR]

In nature, animals or plants often use soft organs to move and hunt. Research works on bioinspired materials and devices have attracted more and more interest as which show the potential for future intelligent robots. As key components of soft robots, biomimetic soft actuators are adapted to greater requirements for convenient, accurate, and programmable controlling robots. Here, a class of materials and processing routes of ultrathin actuators are reported for bioinspired piecewise controllable soft robots, where the actuators associate with thermal‐responsible soft silicone thin film with thickness as thin as 45 µm and electrically driven by well mechanical designed metallic thin film electrodes. Multiple electrodes in the robots in charge of individual segments control allow the soft robots exhibiting similar functionalities of animals or plants (for example, imitating the tongue of a reptile, such as chameleon to hunt moving preys, and mimicking vines to tightly wind around objects). These bionic results in the soft robots demonstrate their advantages in precise and flexible operation, which provides a good reference for the future research of intelligent soft actuators and robots. [ABSTRACT FROM AUTHOR]

Objective: High-density surface electromyography (HD-sEMG) has been utilized extensively in neuromuscular research. Despite its potential advantages, limitations in electrode design have largely prevented widespread acceptance of the technology. Commercial electrodes have limited spatial fidelity, because of a lack of sharpness of the signal, and variable signal stability. We demonstrate here a novel tattoo electrode that addresses these issues. Our dry HD electrode grid exhibits remarkable deformability which ensures superior conformity with the skin surface, while faithfully recording signals during different levels of muscle contraction. Method: We fabricated a 4 cm×3 cm tattoo HD electrode grid on a stretchable electronics membrane for sEMG applications. The grid was placed on the skin overlying the biceps brachii of healthy subjects, and was used to record signals for several hours while tracking different isometric contractions. Results: The sEMG signals were recorded successfully from all 64 electrodes across the grid. These electrodes were able to faithfully record sEMG signals during repeated contractions while maintaining a stable baseline at rest. During voluntary contractions, broad EMG frequency content was preserved, with accurate reproduction of the EMG spectrum across the full signal bandwidth. Conclusion: The tattoo grid electrode can potentially be used for recording high-density sEMG from skin overlying major limb muscles. Layout programmability, good signal quality, excellent baseline stability, and easy wearability make this electrode a potentially valuable component of future HD electrode grid applications. Significance: The tattoo electrode can facilitate high fidelity recording in clinical applications such as tracking the evolution and time-course of challenging neuromuscular degenerative disorders. [ABSTRACT FROM AUTHOR]

Form, fit, and function: Improper fit between the prosthetic socket and the residual limb of persons with amputation causes discomfort, pressure ulcers, and altered load bearing. Kwak and colleagues developed pressure and temperature sensors to monitor the interface between a prosthesis and residual limb. The soft sensors communicated wirelessly with portable electronic devices during walking, sitting, and standing in non-amputees wearing prosthesis simulators and in two individuals with transtibial and transfemoral amputation, respectively. Results support use of wireless sensors to monitor the skin-prosthesis interface. Precise form-fitting of prosthetic sockets is important for the comfort and well-being of persons with limb amputations. Capabilities for continuous monitoring of pressure and temperature at the skin-prosthesis interface can be valuable in the fitting process and in monitoring for the development of dangerous regions of increased pressure and temperature as limb volume changes during daily activities. Conventional pressure transducers and temperature sensors cannot provide comfortable, irritation-free measurements because of their relatively rigid construction and requirements for wired interfaces to external data acquisition hardware. Here, we introduce a millimeter-scale pressure sensor that adopts a soft, three-dimensional design that integrates into a thin, flexible battery-free, wireless platform with a built-in temperature sensor to allow operation in a noninvasive, imperceptible fashion directly at the skin-prosthesis interface. The sensor system mounts on the surface of the skin of the residual limb, in single or multiple locations of interest. A wireless reader module attached to the outside of the prosthetic socket wirelessly provides power to the sensor and wirelessly receives data from it, for continuous long-range transmission to a standard consumer electronic device such as a smartphone or tablet computer. Characterization of both the sensor and the system, together with theoretical analysis of the key responses, illustrates linear, accurate responses and the ability to address the entire range of relevant pressures and to capture skin temperature accurately, both in a continuous mode. Clinical application in two prosthesis users demonstrates the functionality and feasibility of this soft, wireless system. [ABSTRACT FROM AUTHOR]

The dramatic advances in flexible/wearable electronics have garnered great attention for touch sensors for practical applications in human health monitoring and human–machine interfaces. Self-powered triboelectric tactile sensors with high sensitivity, reduced crosstalk, and simple processing routes are highly desirable. Herein, we introduce a facile and low-cost fabrication approach for a metal-electrode free, fully integrated, flexible, and self-powered triboelectric tactile sensor array with 8-by-8 sensor units. Through the height difference between the sensor units and interconnect electrodes, the crosstalk derived from the electrodes has been successfully suppressed with no additional shielding layers. The tactile sensor array shows a remarkable sensitivity of 0.063 V kPa–1 with a linear range from 5 to 50 kPa, which covers a broad range of testing objects. Furthermore, due to the advanced mechanical design, the flexible sensor array exhibits great capability of pressure sensing even under a curved state. The voltage responses from the pattern mapping by finger touching demonstrate the uniformity of the sensor array. Finally, real-time tactile sensing associated with light-emitting diode (LED) array lighting demonstrates the potential application of the sensor array in position tracking, self-powered touch screens, human–machine interfaces and many others. Sensors: Fully integrated, soft sensor array for self-powered tactile sensing A fully integrated soft tactile sensor array (ISTSA) that is self-powered and without metal electrodes has been developed using a low-cost, easily performed fabrication process. A sensor array is a group of sensors used for collecting and processing electromagnetic signals, and arrays of tactile sensors have recently attracted substantial attention with the growth of wearable electronics and application in health monitoring and human-machine interfaces. A team headed by Yunlong Zi at The Chinese University of Hong Kong succeeded in developing an ISTSA with remarkable sensitivity. The ISTSA is so flexible that it exhibits excellent pressure sensing even in a curved state. The authors conducted real-time tactile sensing with LED lighting and finger touching, and they believe their ISTSA has considerable potential for application in such areas as position tracking, self-powered touch screens, and wearable electronics. [ABSTRACT FROM AUTHOR]

Fiber-based electronics enabling lightweight and mechanically flexible/stretchable functions are desirable for numerous e-textile/e-skin optoelectronic applications. These wearable devices require low-cost manufacturing, high reliability, multifunctionality and long-term stability. Here, we report the preparation of representative classes of 3D-inorganic nanofiber network (FN) films by a blow-spinning technique, including semiconducting indium-gallium-zinc oxide (IGZO) and copper oxide, as well as conducting indium-tin oxide and copper metal. Specifically, thin-film transistors based on IGZO FN exhibit negligible performance degradation after one thousand bending cycles and exceptional room-temperature gas sensing performance. Owing to their great stretchability, these metal oxide FNs can be laminated/embedded on/into elastomers, yielding multifunctional single-sensing resistors as well as fully monolithically integrated e-skin devices. These can detect and differentiate multiple stimuli including analytes, light, strain, pressure, temperature, humidity, body movement, and respiratory functions. All of these FN-based devices exhibit excellent sensitivity, response time, and detection limits, making them promising candidates for versatile wearable electronics. Designing energy efficient, flexible opto-electronic systems integrated with textiles remains a challenge. Here, the authors propose a solution-based blow-spinning technique for 3D flexible and stretchable metal oxide nanofiber networks for multimodal and monolithically integrated wearable electronics. [ABSTRACT FROM AUTHOR]

Small animals support a wide range of pathological phenotypes and genotypes as versatile, affordable models for pathogenesis of cardiovascular diseases and for exploration of strategies in electrotherapy, gene therapy, and optogenetics. Pacing tools in such contexts are currently limited to tethered embodiments that constrain animal behaviors and experimental designs. Here, we introduce a highly miniaturized wireless energy-harvesting and digital communication electronics for thin, miniaturized pacing platforms weighing 110 mg with capabilities for subdermal implantation and tolerance to over 200,000 multiaxial cycles of strain without degradation in electrical or optical performance. Multimodal and multisite pacing in ex vivo and in vivo studies over many days demonstrate chronic stability and excellent biocompatibility. Optogenetic stimulation of cardiac cycles with in-animal control and induction of heart failure through chronic pacing serve as examples of modes of operation relevant to fundamental and applied cardiovascular research and biomedical technology. Pacing tools that support small animals and can serve as models for pathogenesis of cardiovascular diseases are currently not available. Here, the authors report a miniaturized wireless battery-free implantable multimodal and multisite pacemaker that provides unlimited stimulation to test subjects. [ABSTRACT FROM AUTHOR]

Traditional technologies for virtual reality (VR) and augmented reality (AR) create human experiences through visual and auditory stimuli that replicate sensations associated with the physical world. The most widespread VR and AR systems use head-mounted displays, accelerometers and loudspeakers as the basis for three-dimensional, computer-generated environments that can exist in isolation or as overlays on actual scenery. In comparison to the eyes and the ears, the skin is a relatively underexplored sensory interface for VR and AR technology that could, nevertheless, greatly enhance experiences at a qualitative level, with direct relevance in areas such as communications, entertainment and medicine1,2. Here we present a wireless, battery-free platform of electronic systems and haptic (that is, touch-based) interfaces capable of softly laminating onto the curved surfaces of the skin to communicate information via spatio-temporally programmable patterns of localized mechanical vibrations. We describe the materials, device structures, power delivery strategies and communication schemes that serve as the foundations for such platforms. The resulting technology creates many opportunities for use where the skin provides an electronically programmable communication and sensory input channel to the body, as demonstrated through applications in social media and personal engagement, prosthetic control and feedback, and gaming and entertainment. Interfaces for epidermal virtual reality technology are demonstrated that can communicate by programmable patterns of localized mechanical vibrations. [ABSTRACT FROM AUTHOR]

B Bioresorbable Cardiac Patch b Bioresorbable materials have great potential in implantable and temporal biomedical devices. Studies by in vitro, and ex vivo models show regular and synchronous contraction of cardiomyocytes on the cardiac patch, biocompatibility, and reconstruction of the conductive pathways. In article number 2303429, Guillermo Antonio Ameer, John A. Rogers, and co-workers demonstrate a highly conductive and elastic bioresorbable cardiac patch to treat myocardial infarction and other cardiac disorders. [Extracted from the article]

Battery-free, soft, skin-mounted wireless sensors enable continuous, full-body spatiotemporal mapping of pressure and temperature on human subjects. Feeling the heat under pressure: Pressure ulcers, or bedsores, can develop at skin sites overlying bony areas of the body when a patient remains in one position for an extended period. These sores can be difficult to detect in their early stages. To begin to address this, Han et al. developed flexible, adherent sensors that measure skin temperature and pressure in real time. The small sensors use wireless power to communicate with external reader antennas. Data acquired from multiple sensors were used to create full-body pressure and temperature maps, which detected changes in pressure due to adjusting the angle of hospital bed incline and changes in skin temperature during sleep in human participants during proof-of-concept studies. Thin, soft, skin-like sensors capable of precise, continuous measurements of physiological health have broad potential relevance to clinical health care. Use of sensors distributed over a wide area for full-body, spatiotemporal mapping of physiological processes would be a considerable advance for this field. We introduce materials, device designs, wireless power delivery and communication strategies, and overall system architectures for skin-like, battery-free sensors of temperature and pressure that can be used across the entire body. Combined experimental and theoretical investigations of the sensor operation and the modes for wireless addressing define the key features of these systems. Studies with human subjects in clinical sleep laboratories and in adjustable hospital beds demonstrate functionality of the sensors, with potential implications for monitoring of circadian cycles and mitigating risks for pressure-induced skin ulcers. [ABSTRACT FROM AUTHOR]

Abstract: The work presented here introduces a materials strategy that involves physically transferred, ultrathin layers of silicon dioxide (SiO2) thermally grown on silicon wafers and then coated with hafnium oxide (HfO2) by atomic layer deposition, as barriers that satisfy requirements for even the most challenging flexible electronic devices. Materials and physics aspects of hydrolysis and ionic transport associated with such bilayers define their performance and reliability characteristics. Systematic experimental studies and reactive diffusion modeling suggest that the HfO2 film, even with some density of pinholes, slows dissolution of the underlying SiO2 by orders of magnitude, independent of the concentration of ions in the surrounding biofluids. Accelerated tests that involve immersion in phosphate‐buffered saline solution at a pH of 7.4 and under a constant electrical bias demonstrate that this bilayer barrier can also obstruct the transport of ions that would otherwise cause drifts in the operation of the electronics. Theoretical drift–diffusion modeling defines the coupling of dissolution and ion diffusion, including their effects on device lifetime. Demonstrations of such barriers with passive and active components in thin, flexible electronic test structures highlight the potential advantages for wide applications in chronic biointegrated devices. [ABSTRACT FROM AUTHOR]

Development of unconventional technologies for wireless collection and analysis of quantitative, clinically relevant information on physiological status is of growing interest. Soft, biocompatible systems are widely regarded as important because they facilitate mounting on external (e.g., skin) and internal (e.g., heart and brain) surfaces of the body. Ultraminiaturized, lightweight, and battery-free devices have the potential to establish complementary options in biointegration, where chronic interfaces (i.e., months) are possible on hard surfaces such as the fingernails and the teeth, with negligible risk for irritation or discomfort. Here, the authors report materials and device concepts for flexible platforms that incorporate advanced optoelectronic functionality for applications in wireless capture and transmission of photoplethysmograms, including quantitative information on blood oxygenation, heart rate, and heart rate variability. Specifically, reflectance pulse oximetry in conjunction with near-field communication capabilities enables operation in thin, miniaturized flexible devices. Studies of the material aspects associated with the body interface, together with investigations of the radio frequency characteristics, the optoelectronic data acquisition approaches, and the analysis methods capture all of the relevant engineering considerations. Demonstrations of operation on various locations of the body and quantitative comparisons to clinical gold standards establish the versatility and the measurement accuracy of these systems, respectively. [ABSTRACT FROM AUTHOR]

A class of thin, lightweight, flexible, near-field communication (NFC) devices with ultraminiaturized format is introduced, and systematic investigations of the mechanics, radio frequency characteristics, and materials aspects associated with their optimized construction are presented. These systems allow advantages in mechanical strength, placement versatility, and minimized interfacial stresses compared to other NFC technologies and wearable electronics. Detailed experimental studies and theoretical modeling of the mechanical and electromagnetic properties of these systems establish understanding of the key design considerations. These concepts can apply to many other types of wireless communication systems including biosensors and electronic implants. [ABSTRACT FROM AUTHOR]

In order to solve the problem of wear-out-failure of diesel engine cylinder, the laser-quenching and low temperature ion sulfurizing complex surface treatment technology was operated on the surface of 42MnCr52 steel. And the tribological properties of the complex layer were investigated. The experimental results indicated that the complex layer was composed of soft surface sulphide layer and sub-surface laserquenching harden layer, and showed excellent friction-reduction and wear-resistance performance at high temperature. The synergistic effect of the complex layer resulted in 20% increase in hardness, 10% reduction in friction coefficient and 50% reduction in wear weight loss, respectively, compared with those of the standard samples. The bench-test further demonstrated that this technology can improve the lubricating condition between cylinder and piston ring, and reduce both abnormity wear when the lubricating oil is deficiency at the time of start-up and sticking wear at high temperature during the operating period, and then prolong the service life of engine. [ABSTRACT FROM AUTHOR]

From the first application of the Boolean model to the cell cycle regulation network of budding yeast, new regulative pathways have been discovered, particularly in the G1/S transition circuit. This discovery called for finer modeling to study the essential biology, and the resulting outcomes are first introduced in the article. A traditional Boolean network model set up for the new G1/S transition circuit shows that it cannot correctly simulate real biology unless the model parameters are fine tuned. The deficiency is caused by an overly coarsegrained description of the inhibitor binding process, which shall be overcome by a two-vector model proposed whose robustness is surveyed using random perturbations. Simulations show that the proposed two-vector model is much more robust in describing inhibitor binding processes within the Boolean framework. [ABSTRACT FROM AUTHOR]

These authors contributed equally: Yong Suk Oh, Jae-Hwan Kim, Zhaoqian Xie. In the Acknowledgements section of this article the grant number relating to Korea Government (MSIT) given for Yong Suk Oh, Seokjoo Cho, Hyeonseok Han, Kyuyoung Kim, Seunghwan Kim, Min Seong Kim, Jungrak Choi, and Inkyu Park was incorrectly given as 2018R1A2B200491013 and should have been 2021R1A2C3008742. [Extracted from the article]

Piezoelectric materials are widely fabricated and investigated for potential applications in microelectromechanical systems as direct converters between mechanical and electrical signals, where some show pyroelectric features involving thermo-electro-mechanical interactions. This study aimed to introduce a novel numerical technique to predict the thermo-electro-mechanical behaviors of piezoelectric structures, based on a strong-form numerical framework called the element differential method. In this method, the shape functions of the isoparametric element and their first two derivatives were derived analytically by interpolating the temperature, displacement, and electric potentials. Then, a point collocation method based on node positions in the elements was proposed to generate the final system of equations without any domain integrations. Thus, the coupled behaviors of thermal piezoelectric structures, including the pyroelectric features, can be simulated by the strong-form formulation of the governing equations. Several numerical examples, including the piezoelectric composites structures, are presented, and the coupled thermo-electro-mechanical responses have been analyzed to validate the proposed method. [ABSTRACT FROM AUTHOR]

Structural topology and loading condition have important influences on the mechanical behaviors of porous soft solids. The porous solids are usually set to be under uniaxial tension or compression. Only a few studies have considered the biaxial loads, especially the combined loads of tension and compression. In this study, porous soft solids with oblique and square lattices of circular voids under biaxial loadings were studied through integrated experiments and numerical simulations. For the soft solids with oblique lattices of circular voids, we found a new pattern transformation under biaxial compression, which has alternating elliptic voids with an inclined angle. This kind of pattern transformation is rarely reported under uniaxial compression. Introducing tensile deformation in one direction can hamper this kind of pattern transformation under biaxial loading. For the soft solids with square lattices of voids, the number of voids cannot change their deformation behaviors qualitatively, but quantitatively. In general, our present results demonstrate that void morphology and biaxial loading can be harnessed to tune the pattern transformations of porous soft solids under large deformation. This discovery offers a new avenue for designing the void morphology of soft solids for controlling their deformation patterns under a specific biaxial stress-state. [ABSTRACT FROM AUTHOR]

A Correction to this paper has been published: https://doi.org/10.1038/s41467-020-20857-y [ABSTRACT FROM AUTHOR]

Bioresorbable electronic stimulators are of rapidly growing interest as unusual therapeutic platforms, i.e., bioelectronic medicines, for treating disease states, accelerating wound healing processes and eliminating infections. Here, we present advanced materials that support operation in these systems over clinically relevant timeframes, ultimately bioresorbing harmlessly to benign products without residues, to eliminate the need for surgical extraction. Our findings overcome key challenges of bioresorbable electronic devices by realizing lifetimes that match clinical needs. The devices exploit a bioresorbable dynamic covalent polymer that facilitates tight bonding to itself and other surfaces, as a soft, elastic substrate and encapsulation coating for wireless electronic components. We describe the underlying features and chemical design considerations for this polymer, and the biocompatibility of its constituent materials. In devices with optimized, wireless designs, these polymers enable stable, long-lived operation as distal stimulators in a rat model of peripheral nerve injuries, thereby demonstrating the potential of programmable long-term electrical stimulation for maintaining muscle receptivity and enhancing functional recovery. Bioresorbable electronic stimulators can deliver electrical stimulation in rodents to enhance functional muscle recovery after nerve injury. Here, the authors present a bioresorbable dynamic covalent polymer that enables reliable, long-lived operation of soft, stretchable devices of this type. [ABSTRACT FROM AUTHOR]

Recent advances in thin, soft skin‐integrated electronics have brought many opportunities in the wearable technics. A simple platform with the functionality of self‐powering for epidermal electronics is reported. These electronics can generate electricity from external mechanical stresses that associates with triboelectric effect, and therefore afford excellent performance in tactile sensing and energy harvesting. Combined advances in materials and mechanics of the skin‐integrated electronics with high efficiency energy harvesting techniques, triboelectric nanogenerators (TENGs) in an epidermal format is realized for the first time. The dots‐distributed electrode pattern allows these electronics exhibiting excellent flexibility and stretchability, distinguishing a broad range of pressures that are relevant to normal body motions. The electricity output of the epidermal device from simple finger tapping modes can achieve >60 V of voltage and >1 µA of current, which is sufficient to light up 15 small light‐emitting diodes. Furthermore, the authors also report a 4 × 4 sensor array based on these TENGs, and demonstrate a skin‐like electronics for real‐time motion monitoring and tactile mapping. [ABSTRACT FROM AUTHOR]

Thin, soft, skin‐like electronics capable of transforming body mechanical motions to electrical signals have broad potential applications in biosensing and energy harvesting. Forming piezoelectric materials into flexible and stretchable formats and integrating with soft substrate would be a considerable strategy for this aspect. Here, a skin‐integrated rubbery electronic device that associates with a simple low‐cost fabrication method for a ternary piezoelectric rubber composite of graphene, lead zirconate tinanate (PZT), and polydimethylsiloxane (PDMS) is introduced. Comparing to the binary composite that blend with PZT and PDMS, the graphene‐embedded ternary composite exhibits a significant enhancement of self‐powered behavior, with a maximum power density of 972.43 µW cm−3 under human walking. Combined experimental and theoretical studies of the graphene‐embedded PZT rubber allow the skin‐integrated electronic device to exhibit excellent mechanical tolerance to bending, stretching, and twisting for thousands of cycles. Customized device geometries guided by optimized mechanical design enable a more comprehensive integration of the rubbery electronics with the human body. For instance, annulus‐shape devices can perfectly mount on the joints and ensure great power output and stability under continuous and large deformations. This work demonstrates the potential of large‐area, skin‐integrated, self‐powered electronics for energy harvesting as well as human health related mechanical sensing. [ABSTRACT FROM AUTHOR]

Bioresorbable electronic technologies form the basis for classes of biomedical devices that undergo complete physical and chemical dissolution after a predefined operational period, thereby eliminating the costs and risks associated with secondary surgical extraction. A continuing area of opportunity is in the development of strategies for power supply for these systems, where previous studies demonstrate some utility for biodegradable batteries, radio frequency harvesters, solar cells, and others. This paper introduces a type of bioresorbable system for wireless power transfer, in which a rotating magnet serves as the transmitter and a bioresorbable antenna as the remote receiver, with capabilities for operation at low frequencies (<200 Hz). Systematic experimental and numerical studies demonstrate several unique advantages of this system, most significantly the elimination of impedance matching and electromagnetic radiation exposure presented with the types of radio frequency energy harvesters explored previously. These results add to the portfolio of power supply options in bioresorbable electronic implants. [ABSTRACT FROM AUTHOR]