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A self-powered system based on energy harvesting technology can be a potential candidate for solving the problem of supplying power to electronic devices. In this review, we focus on portable and wearable self-powered systems, starting with typical energy harvesting technology, and introduce portable and wearable self-powered systems with sensing functions. In addition, we demonstrate the potential of self-powered systems in actuation functions and the development of self-powered systems toward intelligent functions under the support of information processing and artificial intelligence technologies.

Flexible wearable sweat sensors allow continuous, real-time, noninvasive detection of sweat analytes, provide insight into human physiology at the molecular level, and have received significant attention for their promising applications in personalized health monitoring. Electrochemical sensors are the best choice for wearable sweat sensors due to their high performance, low cost, miniaturization, and wide applicability. Recent developments in soft microfluidics, multiplexed biosensing, energy harvesting devices, and materials have advanced the compatibility of wearable electrochemical sweat-sensing platforms. In this review, we summarize the potential of sweat for medical detection and methods for sweat stimulation and collection. This paper provides an overview of the components of wearable sweat sensors and recent developments in materials and power supply technologies and highlights some typical sensing platforms for different types of analytes. Finally, the paper ends with a discussion of the challenges and a view of the prospective development of this exciting field.

The rigidity and relatively primitive modes of operation of catheters equipped with sensing or actuation elements impede their conformal contact with soft-tissue surfaces, limit the scope of their uses, lengthen surgical times and increase the need for advanced surgical skills. Here, we report materials, device designs and fabrication approaches for integrating advanced electronic functionality with catheters for minimally invasive forms of cardiac surgery. By using multiphysics modelling, plastic heart models and Langendorff animal and human hearts, we show that soft electronic arrays in multilayer configurations on endocardial balloon catheters can establish conformal contact with curved tissue surfaces, support high-density spatiotemporal mapping of temperature, pressure and electrophysiological parameters and allow for programmable electrical stimulation, radiofrequency ablation and irreversible electroporation. Integrating multimodal and multiplexing capabilities into minimally invasive surgical instruments may improve surgical performance and patient outcomes. Soft multilayer electronic arrays on endocardial balloon catheters allow for multiplexed high-density spatiotemporal sensing and actuation, as shown in perfused ex vivo hearts.

Recent progress in the synthesis and deterministic assembly of advanced classes of single crystalline inorganic semiconductor nanomaterial establishes a foundation for high-performance electronics on bendable, and even elastomeric, substrates. The results allow for classes of systems with capabilities that cannot be reproduced using conventional wafer-based technologies. Specifically, electronic devices that rely on the unusual shapes/forms/constructs of such semiconductors can offer mechanical properties, such as flexibility and stretchability, traditionally believed to be accessible only via comparatively low-performance organic materials, with superior operational features due to their excellent charge transport characteristics. Specifically, these approaches allow integration of high-performance electronic functionality onto various curvilinear shapes, with linear elastic mechanical responses to large strain deformations, of particular relevance in bio-integrated devices and bio-inspired designs. This review summarizes some recent progress in flexible electronics based on inorganic semiconductor nanomaterials, the key associated design strategies and examples of device components and modules with utility in biomedicine.

Three-dimensional (3D) structures capable of reversible transformations in their geometrical layouts have important applications across a broad range of areas. Most morphable 3D systems rely on concepts inspired by origami/kirigami or techniques of 3D printing with responsive materials. The development of schemes that can simultaneously apply across a wide range of size scales and with classes of advanced materials found in state-of-the-art microsystem technologies remains challenging. Here, we introduce a set of concepts for morphable 3D mesostructures in diverse materials and fully formed planar devices spanning length scales from micrometres to millimetres. The approaches rely on elastomer platforms deformed in different time sequences to elastically alter the 3D geometries of supported mesostructures via nonlinear mechanical buckling. Over 20 examples have been experimentally and theoretically investigated, including mesostructures that can be reshaped between different geometries as well as those that can morph into three or more distinct states. An adaptive radiofrequency circuit and a concealable electromagnetic device provide examples of functionally reconfigurable microelectronic devices.

Efficient and highly functional three-dimensional systems that are ubiquitous in biology suggest that similar design architectures could be useful in electronic and optoelectronic technologies, extending their levels of functionality beyond those achievable with traditional, planar two-dimensional platforms. Complex three-dimensional structures inspired by origami, kirigami have promise as routes for two-dimensional to three-dimensional transformation, but current examples lack the necessary combination of functional materials, mechanics designs, system-level architectures, and integration capabilities for practical devices with unique operational features. Here, we show that two-dimensional semiconductor/semi-metal materials can play critical roles in this context, through demonstrations of complex, mechanically assembled three-dimensional systems for light-imaging capabilities that can encompass measurements of the direction, intensity and angular divergence properties of incident light. Specifically, the mechanics of graphene and MoS 2 , together with strategically configured supporting polymer films, can yield arrays of photodetectors in distinct, engineered three-dimensional geometries, including octagonal prisms, octagonal prismoids, and hemispherical domes. The strain tolerance and promising optoelectronic properties of 2D materials can be leveraged to design functional optical sensing devices. Here, the authors provide a demonstration of arrays of independently addressable photodetectors constructed from graphene and MoS 2 engineered in 3D Kirigami geometries.

Scabiosa comosa and S. tschilliensis (SCST) are traditionally used for liver diseases in Mongolian medicine. However, their active ingredients and molecular mechanisms are unknown. The present study employed network pharmacology and experimental verification approaches to decipher the common pharmacological mechanisms of SCST on liver fibrosis, which is the key step in liver diseases. We predicted the targets of all available SCST ingredients with the SWISS and SuperPred servers and clustered the targets related to liver fibrosis from DrugBank, the OMIM database and the literature. We further evaluated the links between the herbal ingredients and pharmacological actions to explore the potential mechanism of action of SCST. We found that the PPARG signalling pathway could be regulated by SCST for liver fibrosis through enrichment analysis. The key targets included 8 co-targets, including HSP90AA1, PPARG, HSP90AB1, STAT1, etc., which play pivotal roles in the pathogenesis of liver fibrosis. Additionally, the top 15 key compounds included flavonoids and phenylpropanoids. Central to the pathogenesis of liver fibrosis is trans-differentiation or activation of hepatic stellate cells (HSCs). Therefore, LX2 cells, an immortalized human HSC line, were studied. Here, a total 37 components were isolated and identified from the inflorescences of SCST, including the new compound tschilliensisin, and the first separated components, β-sitosterol and luteolin, and these compounds were assessed against anti-hepatic fibrosis. An MTT assay and quantitative real-time polymerase chain reaction (qRT-PCR) and Western blotting analyses demonstrated that the flavonoids of SCST revealed anti-hepatic fibrosis effects via anti-proliferation and increases in the Stat1, Pparg, Hsp90aa1 genes and STAT1 and PPARG proteins in LX-2 cells. In conclusion, these results indicate that SCST has multi-targeted and multi-component synergistic anti-hepatic fibrosis effects.

Piezoelectric microsystems are of use in areas such as mechanical sensing, energy conversion and robotics. The systems typically have a planar structure, but transforming them into complex three-dimensional (3D) frameworks could enhance and extend their various modes of operation. Here, we report a controlled, nonlinear buckling process to convert lithographically defined two-dimensional patterns of electrodes and thin films of piezoelectric polymers into sophisticated 3D piezoelectric microsystems. To illustrate the engineering versatility of the approach, we create more than twenty different 3D geometries. With these structures, we then demonstrate applications in energy harvesting with tailored mechanical properties and root-mean-square voltages ranging from 2 mV to 790 mV, in multifunctional sensors for robotic prosthetic interfaces with improved responsivity (for example, anisotropic responses and sensitivity of 60 mV N −1 for normal force), and in bio-integrated devices with in vivo operational capabilities. The 3D geometries, especially those with ultralow stiffnesses or asymmetric layouts, yield unique mechanical attributes and levels of functionality that would be difficult or impossible to achieve with conventional two-dimensional designs. Nonlinear buckling processes can be used to transform thin films of piezoelectric polymers into sophisticated 3D piezoelectric microsystems with applications in energy harvesting, multifunctional sensing and bio-integrated devices.

Flexible sensors and actuators typically rely on functional materials with low Young's moduli or ultrathin geometries [...].Flexible sensors and actuators typically rely on functional materials with low Young's moduli or ultrathin geometries [...].

Vivid haptic feedback remains a challenge in truly immersive virtual reality and augmented reality. As the tactile sensitivity among different individuals and different parts of the hand within a person varies widely, a universal method to encode tactile information into faithful feedback in hands according to sensitivity features is urgently needed. In addition, existing haptic interfaces worn on the hand are usually bulky, rigid and tethered by cables, which is a hurdle for accurately and naturally providing haptic feedbacks. Here we report a soft, ultrathin, miniaturized and wireless electrotactile system (WeTac) that delivers current through the hand to induce tactile sensations as the skin-integrated haptic interface. With a relatively high pixel density over the whole hand area, the WeTac can provide tactile stimulation and measure the sensation thresholds of users in a flexible way. By mapping the thresholds for different electrical parameters, personalized threshold data can be acquired to reproduce virtual touching sensations on the hand with optimized stimulation intensity and avoid causing pain. With an accurate control of sensation level, temporal and spatial perception, it allows providing personalized feedback when users interact with virtual objects. This technique is promising for a more vivid touching experience in the virtual world and in human–machine interactions. The haptic interface is an essential part of human–machine interfaces where tactile information is delivered between human and machine. Yao et al. develop a soft, ultrathin, miniaturized and wireless electrotactile system that allows virtual tactile information to be reproduced over the hand.