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Large, distributed collections of miniaturized, wireless electronic devices.sup.1,2 may form the basis of future systems for environmental monitoring.sup.3, population surveillance.sup.4, disease management.sup.5 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 seeds.sup.6--we examined passive structures designed for controlled, unpowered flight across natural environments or city settings. Techniques in mechanically guided assembly of three-dimensional (3D) mesostructures.sup.7-9 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., Author(s): Bong Hoon Kim [sup.1] [sup.2] , Kan Li [sup.3] [sup.4] , Jin-Tae Kim [sup.5] , Yoonseok Park [sup.5] , Hokyung Jang [sup.6] , Xueju Wang [sup.7] , Zhaoqian Xie [...]

Standard clinical care in neonatal and pediatric intensive-care units (NICUs and PICUs, respectively) involves continuous monitoring of vital signs with hard-wired devices that adhere to the skin and, in certain instances, can involve catheter-based pressure sensors inserted into the arteries. These systems entail risks of causing iatrogenic skin injuries, complicating clinical care and impeding skin-to-skin contact between parent and child. Here we present a wireless, non-invasive technology that not only offers measurement equivalency to existing clinical standards for heart rate, respiration rate, temperature and blood oxygenation, but also provides a range of important additional features, as supported by data from pilot clinical studies in both the NICU and PICU. These new modalities include tracking movements and body orientation, quantifying the physiological benefits of skin-to-skin care, capturing acoustic signatures of cardiac activity, recording vocal biomarkers associated with tonality and temporal characteristics of crying and monitoring a reliable surrogate for systolic blood pressure. These platforms have the potential to substantially enhance the quality of neonatal and pediatric critical care. Soft electronic patches worn on the skin of infants or children in intensive-care units have a wide range of capabilities in aiding critical care, including monitoring of hemodynamic parameters, cardiac activity, movement and crying., Author(s): Ha Uk Chung [sup.1] [sup.2] [sup.3] , Alina Y. Rwei [sup.1] [sup.3] , Aurélie Hourlier-Fargette [sup.1] [sup.3] , Shuai Xu [sup.1] [sup.3] [sup.4] , KunHyuck Lee [sup.1] [sup.3] [sup.5] [...]

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 medicine.sup.1,2. 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., Author(s): Xinge Yu [sup.1] , Zhaoqian Xie [sup.1] [sup.2] [sup.3] [sup.4] [sup.5] , Yang Yu [sup.6] [sup.7] [sup.8] , Jungyup Lee [sup.9] , Abraham Vazquez-Guardado [sup.10] , Haiwen Luan [sup.10] [...]

Peripheral nerve injuries represent a significant problem in public health, constituting 2-5% of all trauma cases.sup.1. For severe nerve injuries, even advanced forms of clinical intervention often lead to incomplete and unsatisfactory motor and/or sensory function.sup.2. Numerous studies report the potential of pharmacological approaches (for example, growth factors, immunosuppressants) to accelerate and enhance nerve regeneration in rodent models.sup.3-10. Unfortunately, few have had a positive impact in clinical practice. Direct intraoperative electrical stimulation of injured nerve tissue proximal to the site of repair has been demonstrated to enhance and accelerate functional recovery.sup.11,12, suggesting a novel nonpharmacological, bioelectric form of therapy that could complement existing surgical approaches. A significant limitation of this technique is that existing protocols are constrained to intraoperative use and limited therapeutic benefits.sup.13. Herein we introduce (i) a platform for wireless, programmable electrical peripheral nerve stimulation, built with a collection of circuit elements and substrates that are entirely bioresorbable and biocompatible, and (ii) the first reported demonstration of enhanced neuroregeneration and functional recovery in rodent models as a result of multiple episodes of electrical stimulation of injured nervous tissue. A biocompatible device built from naturally dissolving components and controlled by wireless technology enables programmable electrical stimulation of injured rodent peripheral nerves to accelerate regeneration and recovery., Author(s): Jahyun Koo [sup.1] [sup.2] , Matthew R. MacEwan [sup.3] [sup.4] , Seung-Kyun Kang [sup.5] [sup.6] , Sang Min Won [sup.7] , Manu Stephen [sup.3] , Paul Gamble [sup.3] , [...]

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]

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]

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]