Advanced silicon nanomembrane based bioelectronics for flexible and stretchable implantable systems.

In recent years, flexible sensors based on laser-induced graphene (LIG) have played an important role in areas such as smart healthcare, smart skin, and wearable devices. This paper presents the fabrication of flexible sensors based on LIG technology and their applications in human-computer interaction (HCI) systems. Firstly, LIG with a sheet resistance as low as 4.5 Ω per square was generated through direct laser interaction with commercial polyimide (PI) film. The flexible sensors were then fabricated through a one-step method using the as-prepared LIG. The applications of the flexible sensors were demonstrated by an HCI system, which was fabricated through the integration of the flexible sensors and a flexible glove. The as-prepared HCI system could detect the bending motions of different fingers and translate them into the movements of the mouse on the computer screen. At the end of the paper, a demonstration of the HCI system is presented in which words were typed on a computer screen through the bending motion of the fingers. The newly designed LIG-based flexible HCI system can be used by persons with limited mobility to control a virtual keyboard or mouse pointer, thus enhancing their accessibility and independence in the digital realm.

Soft material applied technology has in recent years become more advanced, enabling for, e.g., soft robotics, skin electronics, and wearable systems. Yet, the processing technology of soft materials has not been sufficiently developed to create high performance in soft and stretchable systems, as compared to the processing technology of conventional electronics or electromechanical systems. Liquid alloys have shown excellent properties for soft and stretchable electrical interconnectors and conductors, which is a basic building block to produce electric or electromechanical systems. In order to overcome the limited resolution of previously developed liquid alloy patterning methods for large‐area printed circuits, this work explores the possibility of employing shrinking substrates. By utilizing the characteristics of liquid alloys and elastomers the pattern resolution is improved through a stretch‐shrink patterning (SSP) process. The process provides highly conductive liquid conductors of high resolution and can be combined with existing printing techniques for liquid alloys. The SSP process increases design flexibility of soft and stretchable systems that use liquid alloys and enables designs with finer and denser patterns, and cost‐effective production for small scale systems.

Sulfadimidine (SM2), a potentially carcinogenic sulfonamides,poses a threat to food safety. In this study,a portable electrochemical sensing platform integrated with a smartphone is developed for on-site sulfadimidine (SM2) detection. The electrode utilizes a flexible three-electrode system based on laser-induced porous graphene (LIPG), fabricated via CO₂ laser etching of polyimide (PI) film. The platform is wirelessly connected to a portable electrochemical workstation and smartphone via Bluetooth. Laser parameters, including power and etching depth, are optimized to improve electrochemical performance. The optimized LIPG electrode exhibits significantly improved sensitivity-2.87 and 10.87-fold higher than screen-printed carbon electrode (SPCE) and glassy carbon electrode (GCE), respectively-along with excellent stability (RSD < 0.46% over 99 cycles) and a rapid 10s response time. Quantitative detection of SM2 demonstrates good linearity (3-110μM, R2 = 0.999), with low limits of detection (LOD) of 0.03μM and quantification (LOQ) of 0.1μM. The method is validated in spiked beef (recovery 93.34%-103.70%) and milk (recovery 98.50%-100.80%), confirming its practical applicability. This work is novel in systematically linking laser processing parameters to LIPG electrochemical performance and significant in demonstrating a field-deployable, cost-effective, and smartphone-enabled strategy for monitoring SM2 residues.

The rapid advancement of optoelectronic devices has intensified the demand for materials that are not only functional but also mechanically adaptable to human-centric applications. Conventional transparent conductors, such as indium tin oxide, offer excellent conductivity and optical transparency but fail under mechanical strain, limiting their use in flexible and stretchable systems. This limitation has motivated the development of intrinsically stretchable and transparent conductors capable of maintaining electrical and optical performance under large, repeated deformations. These conductors are typically fabricated by embedding conducting fillers within elastomeric matrices, providing skin-like mechanical compliance without the need for complex geometric patterning and enabling seamless integration with soft, irregular surfaces. Intrinsically stretchable and transparent conductors can be divided into metallic and non-metallic conductors. Each category offers distinct advantages but also presents trade-offs among conductivity, transparency, stretchability, and environmental stability. Therefore, careful material selection and design optimization are essential to balance these competing properties. This review summarizes recent progress in intrinsically stretchable and transparent conductors, with a focus on materials and design strategies for optimizing electrical, optical, and mechanical performance. We further highlight their integration into optoelectronic devices and discuss remaining challenges and potential solutions to advance next-generation soft optoelectronic technologies.

Recent progress in the development of the flexible and stretchable systems with various materials strategies establishes a fundamental basis for a high-performance electronics on the soft and ultrathin bendable elastomeric deformable substrates. The resulting enabled type of functionality cannot be reproduced using conventional wafer-based technologies. These types of electronics on the unusual soft substrates relies on the techniques of either top-down approaches or bottom-up approaches. These approaches allow assemblies of ultra-thin electronics onto various curvilinear shapes, with linear elastic mechanical responses to large strain deformations. However, such electronic devices fabricated using these techniques suffers from the poor device performances compared to that of the conventional rigid substrate based electronics. Here, we report a new technology in flexible electronics based on a new fabrication technique called, “Fully Formed Reverse Device Fabrication.” The key fabrication strategies and examples of various device characteristic allow integration of high-performance electronics with ultra-thin flexible substrates.

The mechanical mismatch between metallic implants and bone tissue is a well-recognized challenge in load-bearing biomedical applications and is commonly associated with stress shielding effects. Architected cellular materials, and in particular auxetic lattice structures, offer a promising route to tailor mechanical response through geometry rather than material substitution alone. However, the mechanical behavior of metallic auxetic lattices fabricated under realistic additive manufacturing conditions, especially their static and fatigue performance, remains insufficiently understood. In this study, the mechanical response of additively manufactured metallic auxetic lattice structures is experimentally investigated using stainless steel 316 L as a well-characterized reference material. Re-entrant auxetic lattice geometries were fabricated via laser-based powder bed fusion (L-PBF) and subjected to controlled post-processing heat treatments. Static tensile and compressive tests, together with compression fatigue experiments, were conducted to evaluate stiffness modulation, strength, deformation stability, and fatigue durability. Finite element analysis was employed as a complementary tool to support interpretation of observations and replicate manufacturing effects, i.e., shape deviation, along the fabrication process chain including heat treatment. The mechanical characterization results demonstrate that auxetic lattice architecture enables substantial stiffness reduction relative to bulk material while maintaining load-bearing capability. Heat-treated specimens exhibited improved ductility and significantly enhanced fatigue resistance compared to as-built structures, highlighting the critical role of post-processing in governing long-term mechanical performance. At the same time, the findings reveal inherent trade-offs between stiffness reduction and strength in highly porous auxetic lattices. Overall, this work provides experimentally grounded insights into the structure–property relationships of metallic auxetic lattices manufactured by L-PBF. By clarifying the mechanical mechanisms that control stiffness, strength, and fatigue response, the study establishes a mechanical foundation for future investigations involving optimized geometries, advanced materials, and application-specific requirements, including orthopedic implant design.

Flexible and reusable parylene C mask technology for applications in cascade impactor air quality monitoring systems

It is a well-known fact that the use of artificial fibers is increasing today. However, some reasons such as the high amount of chemicals, energy, water used in the production of artificial fibers and environmental pollution, allergic reactions on the skin it comes into contact with, and not being destroyed in nature for a long time have caused natural fibers have been preferred again. Among these fibers, which have been most preferred from the past to the present, wool fiber comes after cotton. The products produced from wool fiber provide the comfort features expected for the user in the best way, with their elasticity, drape, brightness, adaptability to the human body's thermal responses, and rapid transfer of heat and water vapor. Nowadays, the emergence of the need for functional and comfortable clothing in business life has necessitated different patterns and construction studies in wool fabrics. For this reason, different searches have emerged in conventional patterning (dobby patterning) techniques made on classical wool fabrics. The need to expand the boundaries of patterning studies created with conventional production techniques, different knitting, and yarn colors has led to the emergence of new patterns with printing techniques. In this study, different printing pattern studies were carried out on woolen dress/uniform fabrics in different constructions and weights. The pattern studies were carried out on woolen fabrics by using colors with different themes. As a result of printing patterns on woolen fabrics, it was aimed to increase the use of wool-based products in daily clothing.

Reliable energy access in rural schools is necessary for educational and community development. Solar hybrid systems, particularly Direct Current (DC) Coupled designs, offer a sustainable solution. However, they face significant scalability, maintenance complexity, and charge controller dependency challenges. This paper addresses these issues and presents an adaptive model to optimize DC Coupled solar hybrid systems. Applying Basic Qualitative Inquiry, semi-structured interviews were conducted during this study with five experts, including site officers, maintenance contractors, and a senior electrical engineer. The results reveal that rigid system design, high upgrading costs, and charge controller inefficiencies limit scalability and long-term performance. System reliability will suffer from a lack of maintenance, especially battery management and overheating prevention. The Adaptive DC Coupled System Solution Model (ADCSM) was proposed to overcome these challenges, including adaptive system restructuring, AC-DC hybrid integration, advanced charge controller optimization technologies, and intelligent monitoring technologies. This paradigm improves the system's flexibility, efficiency, and sustainability and provides a cost-effective and scalable strategy for policymakers, engineers, and researchers to manage rural energy. Keywords: Solar Hybrid Systems, DC Coupled, Scalability Challenges, Charge Controller Optimization, Renewable Energy in Rural Schools.

Capabilities in health monitoring enabled by capture and quantitative chemical analysis of sweat could complement, or potentially obviate the need for, approaches based on sporadic assessment of blood samples. Established sweat monitoring technologies use simple fabric swatches and are limited to basic analysis in controlled laboratory or hospital settings. We present a collection of materials and device designs for soft, flexible, and stretchable microfluidic systems, including embodiments that integrate wireless communication electronics, which can intimately and robustly bond to the surface of the skin without chemical and mechanical irritation. This integration defines access points for a small set of sweat glands such that perspiration spontaneously initiates routing of sweat through a microfluidic network and set of reservoirs. Embedded chemical analyses respond in colorimetric fashion to markers such as chloride and hydronium ions, glucose, and lactate. Wireless interfaces to digital image capture hardware serve as a means for quantitation. Human studies demonstrated the functionality of this microfluidic device during fitness cycling in a controlled environment and during long-distance bicycle racing in arid, outdoor conditions. The results include quantitative values for sweat rate, total sweat loss, pH, and concentration of chloride and lactate.

Recent advances in nanolithography, miniaturization, and material science, along with developments in wearable electronics, are pushing the frontiers of sensor technology into the large-scale fabrication of highly sensitive, flexible, stretchable, and multimodal detection systems. Various strategies, including surface engineering, have been developed to control the electrical and mechanical characteristics of sensors. In particular, surface wrinkling provides an effective alternative for improving both the sensing performance and mechanical deformability of flexible and stretchable sensors by releasing interfacial stress, preventing electrical failure, and enlarging surface areas. In this study, recent developments in the fabrication strategies of wrinkling structures for sensor applications are discussed. The fundamental mechanics, geometry control strategies, and various fabricating methods for wrinkling patterns are summarized. Furthermore, the current state of wrinkling approaches and their impacts on the development of various types of sensors, including strain, pressure, temperature, chemical, photodetectors, and multimodal sensors, are reviewed. Finally, existing wrinkling approaches, designs, and sensing strategies are extrapolated into future applications.

The construction of lightweight, flexible and stretchable power systems for modern electronic devices without using elastic polymer substrates is critical but remains challenging. We have developed a new and general strategy to produce both freestanding, stretchable, and flexible supercapacitors and lithium‐ion batteries with remarkable electrochemical properties by designing novel carbon nanotube fiber springs as electrodes. These springlike electrodes can be stretched by over 300 %. In addition, the supercapacitors and lithium‐ion batteries have a flexible fiber shape that enables promising applications in electronic textiles.

Macroscale and multi-functional flexible sensor networks have been widely proposed for the Internet of Things (IoT) and the trillion sensor networks. In this report, our recent progress of flexible sensors fabricated by some printing methods on user-defined non-planer substrates is presented. Especially, flexible strain sensor and temperature sensors are discussed to monitor human condition as a health monitoring device and to detect an object for a robotic prosthesis skin. In addition, flexible digital and analog circuits for the future fully integrated flexible device system are introduced.

A new approach has been developed for determining layered elastic moduli from in situ load-deflection data. This approach is called forwardcalculation, and it differs from backcalculation in that modulus values are calculated directly from the load-deflection data by using closed-form formulas rather than through iteration. The closed-form equations are used for the subgrade and the bound surface course for both flexible and rigid pavement systems. Intermediate-layer moduli are estimated through commonly used modular ratios between adjacent layers. The entire pre-1998 Long-Term Pavement Performance (LTPP) set of backcalculated results was screened with forwardcalculated moduli. Because both back-and forwardcalculation techniques use identical falling weight deflectometer load-deflection data as input, it was expected that the moduli derived from each approach should be reasonably close to each other. This result was not always the case, however. Forwardcalculated values were, in most cases, more stable on a section-by-section basis than the backcalculated values in the LTPP database. Similarly, the forwardcalculated values usually appeared more reasonable. The exception to this finding was the portion of the database based on slab-on-dense-liquid or slab-on-elastic-solid theory, in which the correspondence between the two approaches was excellent, and both approaches were stable.

A finite element (FE) response model has been developed to describe stress and strain response parameters for geosynthetic-reinforced flexible pavement systems where the geosynthetic is placed at the bottom of the unbound aggregate layer. The model contains membrane elements and an anisotropic linear-elastic material model for the geosynthetic inclusion. Elasto-plastic models are used for the asphalt concrete, base aggregate and subgrade layers. Principal response parameters extracted from the FE model include vertical strain in the top of the subgrade and bulk stress in the unbound base aggregate layer. These response parameters are used in empirical damage models for the prediction of long-term pavement performance and the definition of reinforcement benefit. Reinforcement benefit is defined in terms of an extension of service life of the pavement, a reduction in aggregate thickness for equivalent service life, or a combination of the two. The damage models are calibrated from reinforced and unreinforced pavement test sections. The model is shown to provide general descriptions of reinforcement mechanisms that are consistent with those previously observed in instrumented pavement test sections. A companion paper (S.W., Perkins and M.Q., Edens (2003) A Design Model for Geosynthetic-Reinforced Pavements, International Journal of Pavement Engineering) describes the use of the response and damage models in a parametric study from which a design model for geosynthetic-reinforced pavements is developed.