A Generic Strategy to Create Mechanically Interlocked Nanocomposite/Hydrogel Hybrid Electrodes for Epidermal Electronics

Stretchable electronics are crucial enablers for next-generation wearables intimately integrated into the human body.As the primary compliant conductors used in these devices,metallic nanostructure/elastomer composites often struggle to form conformal contact with the textured skin.Hybrid electrodes have been consequently developed based on conductive nanocomposite and soft hydrogels to establish seamless skin-device interfaces.However,chemical modifications are typically needed for reliable bonding,which can alter their original properties.To overcome this limitation,this study presents a facile fabrication approach for mechanically interlocked nanocomposite/hydrogel hybrid electrodes.In this physical process,soft microfoams are thermally laminated on silver nanowire nanocomposites as a porous interface,which forms an interpenetrating network with the hydrogel.The microfoam-enabled bonding strategy is generally compatible with various polymers.The resulting interlocked hybrids have a 28-fold improved interfacial toughness compared to directly stacked hybrids.These electrodes achieve firm attachment to the skin and low contact impedance using tissue-adhesive hydrogels.They have been successfully integrated into an epidermal sleeve to distinguish hand gestures by sensing mus-cle contractions.Interlocked nanocomposite/hydrogel hybrids reported here offer a promising platform to combine the benefits of both materials for epidermal devices and systems.

Advances in Wireless,Batteryless,Implantable Electronics for Real‑Time,Continuous Physiological Monitoring

This review summarizes recent progress in developing wireless,batteryless,fully implantable biomedical devices for real-time continuous physiological signal monitoring,focusing on advancing human health care.Design considerations,such as biological constraints,energy sourcing,and wireless communication,are discussed in achieving the desired performance of the devices and enhanced interface with human tissues.In addition,we review the recent achievements in materials used for developing implantable systems,emphasizing their importance in achieving multi-functionalities,biocompatibility,and hemocompatibility.The wireless,batteryless devices offer minimally invasive device insertion to the body,enabling portable health monitoring and advanced disease diagnosis.Lastly,we summarize the most recent practical applications of advanced implantable devices for human health care,highlighting their potential for immediate commercialization and clinical uses.

3D‑Printed Carbon‑Based Conformal Electromagnetic Interference Shielding Module for Integrated Electronics

Electromagnetic interference shielding(EMI SE)modules are the core com-ponent of modern electronics.However,the tra-ditional metal-based SE modules always take up indispensable three-dimensional space inside electronics,posing a major obstacle to the integra-tion of electronics.The innovation of integrating 3D-printed conformal shielding(c-SE)modules with packaging materials onto core electronics offers infinite possibilities to satisfy ideal SE func-tion without occupying additional space.Herein,the 3D printable carbon-based inks with various proportions of graphene and carbon nanotube nanoparticles are well-formulated by manipulating their rheological peculiarity.Accordingly,the free-constructed architectures with arbitrarily-customized structure and multifunctionality are created via 3D printing.In particular,the SE performance of 3D-printed frame is up to 61.4 dB,simultaneously accompanied with an ultralight architecture of 0.076 g cm^(-3) and a superhigh specific shielding of 802.4 dB cm3 g^(-1).Moreover,as a proof-of-concept,the 3D-printed c-SE module is in situ integrated into core electronics,successfully replacing the traditional metal-based module to afford multiple functions for electromagnetic compatibility and thermal dissipa-tion.Thus,this scientific innovation completely makes up the blank for assembling carbon-based c-SE modules and sheds a brilliant light on developing the next generation of high-performance shielding materials with arbitrarily-customized structure for integrated electronics.

Design and prototyping of the readout electronics for the transition radiation detector in the high energy cosmic radiation detection facility

The high energy cosmic-radiation detection(HERD)facility is planned to launch in 2027 and scheduled to be installed on the China Space Station.It serves as a dark matter particle detector,a cosmic ray instrument,and an observatory for high-energy gamma rays.A transition radiation detector placed on one of its lateral sides serves dual purpose,(ⅰ)calibrating HERD's electromagnetic calorimeter in the TeV energy range,and(ⅱ)serving as an independent detector for high-energy gamma rays.In this paper,the prototype readout electronics design of the transition radiation detector is demonstrated,which aims to accurately measure the charge of the anodes using the SAMPA application specific integrated circuit chip.The electronic performance of the prototype system is evaluated in terms of noise,linearity,and resolution.Through the presented design,each electronic channel can achieve a dynamic range of 0–100 fC,the RMS noise level not exceeding 0.15 fC,and the integral nonlinearity was<0.2%.To further verify the readout electronic performance,a joint test with the detector was carried out,and the results show that the prototype system can satisfy the requirements of the detector's scientific goals.

Advancements in transfer printing techniques for flexible electronics:adjusting interfaces and promoting versatility

The burgeoning interest in flexible electronics necessitates the creation of patterning technology specifically tailored for flexible substrates and complex surface morphologies.Among a variety of patterning techniques,transfer printing emerges as one of the most efficient,cost-effective,and scalable methods.It boasts the ability for high-throughput fabrication of 0–3D micro-and nano-structures on flexible substrates,working in tandem with traditional lithography methods.This review highlights the critical issue of transfer printing:the flawless transfer of devices during the pick-up and printing process.We encapsulate recent advancements in numerous transfer printing techniques,with a particular emphasis on strategies to control adhesion forces at the substrate/device/stamp interfaces.These strategies are employed to meet the requirements of competing fractures for successful pick-up and print processes.The mechanism,advantages,disadvantages,and typical applications of each transfer printing technique will be thoroughly discussed.The conclusion section provides design guidelines and probes potential directions for future advancements.

Fully Recyclable Liquid Metal-Based Ultra-St retch able Electronics Enabled by Water-Modulation-Degradation-Reconstruction Polymer-Gel

The rapid development of stretchable electronics made by circuits,microchips,and encapsulation elastomers has caused the production of a large amount of electronic waste(e-waste).The degradation of elastomers can highly minimize the negative effects of e-wastes.However,chemicals that included acid,alkali,and organics were repeatedly used during the recycling process,which were environmentally unfriendly.Here,a water-modulation-degradation-reconstruction(WDR)polyvinylpyrrolidone(PVP)-honey composite(PHC)polymer-gel was developed and could be regarded as encapsulation elastomers to realize a fully recyclable water-degradable stretchable(WS)electronics with multi-functions.The stretchability of the PHC polymer-gel could be modulated by the change of its water retention.The Chip-integrated liquid metal(LM)circuits encapsulated with the modulated PHC encapsulation elastomer could withstand a strain value of~3000%.Moreover,we developed a WS biomedical sensor composed of PHC encapsulation elastomer,LM circuits,and microchips,which could be fully recycled by biodegrading it in water to reconstruct a new one.As before,the reconstructed WS biomedical sensor could still simultaneously realize the combination of ultra-stretchability,recycling,self-healing,self-adhesive,and self-conformal abilities.The results revealed that this study exercises a profound influence on the rational design of multi-functional WS electronics.

Novel fabrication techniques for ultra-thin silicon based flexible electronics

Flexible electronics offer a multitude of advantages,such as flexibility,lightweight property,portability,and high durability.These unique properties allow for seamless applications to curved and soft surfaces,leading to extensive utilization across a wide range of fields in consumer electronics.These applications,for example,span integrated circuits,solar cells,batteries,wearable devices,bio-implants,soft robotics,and biomimetic applications.Recently,flexible electronic devices have been developed using a variety of materials such as organic,carbon-based,and inorganic semiconducting materials.Silicon(Si)owing to its mature fabrication process,excellent electrical,optical,thermal properties,and cost efficiency,remains a compelling material choice for flexible electronics.Consequently,the research on ultra-thin Si in the context of flexible electronics is studied rigorously nowadays.The thinning of Si is crucially important for flexible electronics as it reduces its bending stiffness and the resultant bending strain,thereby enhancing flexibility while preserving its exceptional properties.This review provides a comprehensive overview of the recent efforts in the fabrication techniques for forming ultra-thin Si using top-down and bottom-up approaches and explores their utilization in flexible electronics and their applications.

On-Chip Micro Temperature Controllers Based on Freestanding Thermoelectric Nano Films for Low-Power Electronics

Multidimensional integration and multifunctional com-ponent assembly have been greatly explored in recent years to extend Moore’s Law of modern microelectronics.However,this inevitably exac-erbates the inhomogeneity of temperature distribution in microsystems,making precise temperature control for electronic components extremely challenging.Herein,we report an on-chip micro temperature controller including a pair of thermoelectric legs with a total area of 50×50μm^(2),which are fabricated from dense and flat freestanding Bi2Te3-based ther-moelectric nano films deposited on a newly developed nano graphene oxide membrane substrate.Its tunable equivalent thermal resistance is controlled by electrical currents to achieve energy-efficient temperature control for low-power electronics.A large cooling temperature difference of 44.5 K at 380 K is achieved with a power consumption of only 445μW,resulting in an ultrahigh temperature control capability over 100 K mW^(-1).Moreover,an ultra-fast cooling rate exceeding 2000 K s^(-1) and excellent reliability of up to 1 million cycles are observed.Our proposed on-chip temperature controller is expected to enable further miniaturization and multifunctional integration on a single chip for microelectronics.

A comprehensive review on microchannel heat sinks for electronics cooling

The heat generation of electronic devices is increasing dramatically,which causes a serious bottleneck in the thermal management of electronics,and overheating will result in performance deterioration and even device damage.With the development of micro-machining technologies,the microchannel heat sink(MCHS)has become one of the best ways to remove the considerable amount of heat generated by high-power electronics.It has the advantages of large specific surface area,small size,coolant saving and high heat transfer coefficient.This paper comprehensively takes an overview of the research progress in MCHSs and generalizes the hotspots and bottlenecks of this area.The heat transfer mechanisms and performances of different channel structures,coolants,channel materials and some other influencing factors are reviewed.Additionally,this paper classifies the heat transfer enhancement technology and reviews the related studies on both the single-phase and phase-change flow and heat transfer.The comprehensive review is expected to provide a theoretical reference and technical guidance for further research and application of MCHSs in the future.

Wearable Triboelectric Nanogenerators Based on Printed Polyvinylidene Fluoride Films Incorporated with Cobalt-Based Metal-Organic Framework for Self-Powered Mobile Electronics

In this study,wearable triboelectric nanogenerators comprising bar-printed polyvinylidene fluoride(PVDF)films incorporated with cobalt-based metal-organic framework(Co-MOF)were developed.The enhanced output performance of the TENGs was attributed to the phase transition of PVDF from a-crystals toβ-crystals,as facilitated by the incorporation of the MOF.The synthesis conditions,including metal ion,concentration,and particle size of the MOF,were optimized to increase open-circuit voltage(VOC)and open-circuit current(I_(SC))of PVDF-based TENGs.In addition to high operational stability,mechanical robustness,and long-term reliability,the developed TENG consisting of PVDF incorporated with Co-MOF(Co-MOF@PVDF)achieved a VOC of 194 V and an I_(SC)of 18.8μA.Furthermore,the feasibility of self-powered mobile electronics was demonstrated by integrating the developed wearable TENG with rectifier and control units to power a global positioning system(GPS)device.The local position of the user in real-time through GPS was displayed on a mobile interface,powered by the battery charged through friction-induced electricity generation.

Numerical Investigation on Thermal Performance of Two-Phase Immersion Cooling Method for High-Power Electronics

The power density of electronic components grows continuously,and the subsequent heat accumulation and temperature increase inevitably affect electronic equipment’s stability,reliability and service life.Therefore,achieving efficient cooling in limited space has become a key problem in updating electronic devices with high performance and high integration.Two-phase immersion is a novel cooling method.The computational fluid dynamics(CFD)method is used to investigate the cooling performance of two-phase immersion cooling on high-power electronics.The two-dimensional CFD model is utilized by the volume of fluid(VOF)method and Reynolds StressModel.Lee’s model was employed to calculate the phase change rate.The heat transfer coefficient along the heatedwalls and the shear-lift force on bubbles are calculated.The simulation data are verified with the literature results.The cooling performance of different coolants has been studied.The results indicate that the boiling heat transfer coefficient can be enhanced by using a low boiling point coolant.The methanol is used as the cooling medium for further research.In addition,the mass flow rate and inlet temperature are investigated to assess the thermal performance of twophase immersion cooling.The average temperature of the high-power electronics is 80℃,and the temperature difference can be constrained to 8℃.Meanwhile,the convective heat transfer coefficient reaches 2740 W/(m2・℃)when the inlet temperature is 50℃,and the mass flow rate is 0.3 kg/s.In conclusion,the results demonstrated that two-phase immersion cooling has provided an effective method for the thermal management of high-power electronics.

Application of Power Electronics Converters in Renewable Energy

Against the backdrop of global energy shortages and increasingly severe environmental pollution,renewable energy is gradually becoming a significant direction for future energy development.Power electronics converters,as the core technology for energy conversion and control,play a crucial role in enhancing the efficiency and stability of renewable energy systems.This paper explores the basic principles and functions of power electronics converters and their specific applications in photovoltaic power generation,wind power generation,and energy storage systems.Additionally,it analyzes the current innovations in high-efficiency energy conversion,multilevel conversion technology,and the application of new materials and devices.By studying these technologies,the aim is to promote the widespread application of power electronics converters in renewable energy systems and provide theoretical and technical support for achieving sustainable energy development.

Heterogeneous Cu_(x)O Nano‑Skeletons from Waste Electronics for Enhanced Glucose Detection

Electronic waste(e-waste)and diabetes are global challenges to modern societies.However,solving these two challenges together has been challenging until now.Herein,we propose a laser-induced transfer method to fabricate portable glucose sensors by recycling copper from e-waste.We bring up a laser-induced full-automatic fabrication method for synthesizing continuous heterogeneous Cu_(x)O(h-Cu_(x)O)nano-skeletons electrode for glucose sensing,offering rapid(<1 min),clean,air-compatible,and continuous fabrication,applicable to a wide range of Cu-containing substrates.Leveraging this approach,h-Cu_(x)O nanoskeletons,with an inner core predominantly composed of Cu_(2)O with lower oxygen content,juxtaposed with an outer layer rich in amorphous Cu_(x)O(a-Cu_(x)O)with higher oxygen content,are derived from discarded printed circuit boards.When employed in glucose detection,the h-Cu_(x)O nano-skeletons undergo a structural evolution process,transitioning into rigid Cu_(2)O@CuO nano-skeletons prompted by electrochemical activation.This transformation yields exceptional glucose-sensing performance(sensitivity:9.893 mA mM^(-1) cm^(-2);detection limit:0.34μM),outperforming most previously reported glucose sensors.Density functional theory analysis elucidates that the heterogeneous structure facilitates gluconolactone desorption.This glucose detection device has also been downsized to optimize its scalability and portability for convenient integration into people’s everyday lives.

ZnO nanowires based degradable high-performance photodetectors for eco-friendly green electronics

Disposable devices designed for single and/or multiple reliable measurements over a short duration have attracted considerable interest recently. However, these devices often use non-recyclable and non-biodegradable materials and wasteful fabrication methods. Herein, we present ZnO nanowires(NWs) based degradable high-performance UV photodetectors(PDs) on flexible chitosan substrate. Systematic investigations reveal the presented device exhibits excellent photo response, including high responsivity(55 A/W), superior specific detectivity(4×10^(14) jones), and the highest gain(8.5×10~(10)) among the reported state of the art biodegradable PDs. Further, the presented PDs display excellent mechanical flexibility under wide range of bending conditions and thermal stability in the measured temperature range(5–50 ℃).The biodegradability studies performed on the device, in both deionized(DI) water(pH≈6) and PBS solution(pH=7.4),show fast degradability in DI water(20 mins) as compared to PBS(48 h). These results show the potential the presented approach holds for green and cost-effective fabrication of wearable, and disposable sensing systems with reduced adverse environmental impact.

Soft Electronics for Health Monitoring Assisted by Machine Learning

Due to the development of the novel materials,the past two decades have witnessed the rapid advances of soft electronics.The soft electronics have huge potential in the physical sign monitoring and health care.One of the important advantages of soft electronics is forming good interface with skin,which can increase the user scale and improve the signal quality.Therefore,it is easy to build the specific dataset,which is important to improve the performance of machine learning algorithm.At the same time,with the assistance of machine learning algorithm,the soft electronics have become more and more intelligent to realize real-time analysis and diagnosis.The soft electronics and machining learning algorithms complement each other very well.It is indubitable that the soft electronics will bring us to a healthier and more intelligent world in the near future.Therefore,in this review,we will give a careful introduction about the new soft material,physiological signal detected by soft devices,and the soft devices assisted by machine learning algorithm.Some soft materials will be discussed such as two-dimensional material,carbon nanotube,nanowire,nanomesh,and hydrogel.Then,soft sensors will be discussed according to the physiological signal types(pulse,respiration,human motion,intraocular pressure,phonation,etc.).After that,the soft electronics assisted by various algorithms will be reviewed,including some classical algorithms and powerful neural network algorithms.Especially,the soft device assisted by neural network will be introduced carefully.Finally,the outlook,challenge,and conclusion of soft system powered by machine learning algorithm will be discussed.

Rational Design of Cellulosic Triboelectric Materials for Self‑Powered Wearable Electronics

With the rapid development of the Internet of Things and flexible electronic technologies,there is a growing demand for wireless,sustainable,multifunctional,and independently operating self-powered wearable devices.Nevertheless,structural flexibility,long operating time,and wearing comfort have become key requirements for the widespread adoption of wearable electronics.Triboelectric nanogenerators as a distributed energy harvesting technology have great potential for application development in wearable sensing.Compared with rigid electronics,cellulosic self-powered wearable electronics have significant advantages in terms of flexibility,breathability,and functionality.In this paper,the research progress of advanced cellulosic triboelectric materials for self-powered wearable electronics is reviewed.The interfacial characteristics of cellulose are introduced from the top-down,bottom-up,and interfacial characteristics of the composite material preparation process.Meanwhile,the modulation strategies of triboelectric properties of cellulosic triboelectric materials are presented.Furthermore,the design strategies of triboelectric materials such as surface functionalization,interfacial structure design,and vacuum-assisted self-assembly are systematically discussed.In particular,cellulosic self-powered wearable electronics in the fields of human energy harvesting,tactile sensing,health monitoring,human–machine interaction,and intelligent fire warning are outlined in detail.Finally,the current challenges and future development directions of cellulosic triboelectric materials for self-powered wearable electronics are discussed.

Fabrication of polyetheretherketone(PEEK)-based 3D electronics with fine resolution by a hydrophobic treatment assisted hybrid additive manufacturing method

Additive manufacturing(AM)is a free-form technology that shows great potential in the integrated creation of three-dimensional(3D)electronics.However,the fabrication of 3D conformal circuits that fulfill the requirements of high service temperature,high conductivity and high resolution remains a challenge.In this paper,a hybrid AM method combining the fused deposition modeling(FDM)and hydrophobic treatment assisted laser activation metallization(LAM)was proposed for manufacturing the polyetheretherketone(PEEK)-based 3D electronics,by which the conformal copper patterns were deposited on the 3D-printed PEEK parts,and the adhesion between them reached the 5B high level.Moreover,the 3D components could support the thermal cycling test from-55℃ to 125℃ for more than 100 cycles.Particularly,the application of a hydrophobic coating on the FDM-printed PEEK before LAM can promote an ideal catalytic selectivity on its surface,not affected by the inevitable printing borders and pores in the FDM-printed parts,then making the resolution of the electroless plated copper lines improved significantly.In consequence,Cu lines with width and spacing of only60μm and 100μm were obtained on both as-printed and after-polished PEEK substrates.Finally,the potential of this technique to fabricate 3D conformal electronics was demonstrated.

Biological Tissue-Inspired Ultrasoft,Ultrathin,and Mechanically Enhanced Microfiber Composite Hydrogel for Flexible Bioelectronics

Hydrogels offer tissue-like softness,stretchability,fracture toughness,ionic conductivity,and compatibility with biological tissues,which make them promising candidates for fabricating flexible bioelectronics.A soft hydrogel film offers an ideal interface to directly bridge thin-film electronics with the soft tissues.However,it remains difficult to fabricate a soft hydrogel film with an ultrathin configuration and excellent mechanical strength.Here we report a biological tissue-inspired ultrasoft microfiber composite ultrathin(<5μm)hydrogel film,which is currently the thinnest hydrogel film as far as we know.The embedded microfibers endow the composite hydrogel with prominent mechanical strength(tensile stress~6 MPa)and anti-tearing property.Moreover,our microfiber composite hydrogel offers the capability of tunable mechanical properties in a broad range,allowing for matching the modulus of most biological tissues and organs.The incorporation of glycerol and salt ions imparts the microfiber composite hydrogel with high ionic conductivity and prominent anti-dehydration behavior.Such microfiber composite hydrogels are promising for constructing attaching-type flexible bioelectronics to monitor biosignals.

Textile electronics for wearable applications

Textile electronics have become an indispensable part of wearable applications because of their large flexibility,light-weight,comfort and electronic functionality upon the merge of textiles and microelectronics.As a result,the fabrication of functional fibrous materials and the integration of textile electronic devices have attracted increasing interest in the wearable electronic community.Challenges are encountered in the development of textile electronics in a way that is electrically reliable and durable,without compromising on the deformability and comfort of a garment,including processing multiple materials with great mismatches in mechanical,thermal,and electrical properties and assembling various structures with the disparity in dimensional scales and surface roughness.Equal challenges lie in high-quality and cost-effective processes facilitated by high-level digital technology enabled design and manufacturing methods.This work reviews the manufacturing of textile-shaped electronics via the processing of functional fibrous materials from the perspective of hierarchical architectures,and discusses the heterogeneous integration of microelectronics into normal textiles upon the fabric circuit board and adapted electrical connections,broadly covering both conventional and advanced textile electronic production processes.We summarize the applications and obstacles of textile electronics explored so far in sensors,actuators,thermal management,energy fields,and displays.Finally,the main conclusions and outlook are provided while the remaining challenges of the fabrication and application of textile electronics are emphasized.

Electronics system for the cosmic X-ray polarization detector

This study presents an electronics system for cosmic X-ray polarization detection(CXPD).The CXPD was designed as a high-sensitivity soft X-ray polarimeter with a measurement energy range of 2-10 keV carried by a CubeSat.A stable and functionally complete electronics system under power and space constraints is a key challenge.The complete CXPD electronics system(CXPDES)comprises hardware and firmware.CXPDES adopts a three-layer electronic board structure based on functionality and available space.Two gas pixel detectors(GPDs)were placed on the top layer board,and CXPDES provided the GPDs with voltages up to-4000 V.Each GPD signal was digitized,compressed,encoded,and stored before being transmitted to the ground.The CXPDES provided stable and high-speed communication based on a scheme that separated command and data transmission,and it supports the CXPDES in-orbit upgrade.In addition,environmental monitors,silicon photomultiplier(SiPM)triggers,power management,GPDs configuration,and mode switches were included in the overall operating logic of the CXPDES.The results obtained by testing the CXPDES showed that it satisfied all the requirements of CXPD.The CXPDES provides design experience and technological readiness for future large-area X-ray polarimetry missions.