Low Thermal Conductivity and Diffusivity at High Temperatures Using Stable High-Entropy Spinel Oxide Nanoparticles.

The realization of low thermal conductivity at high temperatures (0.11 W m K 800 °C) in ambient air in a porous solid thermal insulation material, using stable packed nanoparticles of high-entropy spinel oxide with 8 cations (HESO-8 NPs) with a relatively high packing density of ≈50%, is reported. The high-density HESO-8 NP pellets possess around 1000-fold lower thermal diffusivity than that of air, resulting in much slower heat propagation when subjected to a transient heat flux.

Liquid Crystal Elastomer for Compression Therapy.

Compression therapy is a widely used treatment for various disorders including venous leg ulcers. Traditional methods such as inelastic bandages and elastic stockings, have limitations in maintaining optimal pressure over time. Dynamic therapy devices offer intermittent pressure cycles but are often bulky or rigid.

Modeling nematic phase main-chain liquid crystal elastomer synthesis, mechanics, and thermal actuation coarse-grained molecular dynamics.

This paper presents a coarse-grained molecular dynamics simulation study of the synthesis, mechanics, and thermal actuation of nematic phase main-chain liquid crystal elastomers (LCEs), a type of soft, temperature-responsive, polymeric actuating material. The simulations herein model the crosslinking, mechanical stretching, and additional crosslinking synthesis process, following which, the simulated LCE exhibits a direction-dependent thermal actuation and mechanical response. The thermal actuation response shows good qualitative agreement with experimental results, including the variation of a global order parameter that describes the orientation of the mesogen domains comprising the LCE.

Soft elasticity enabled adhesion enhancement of liquid crystal elastomers on rough surfaces.

The fabrication of pressure-sensitive adhesives (PSA) using liquid crystal elastomers (LCE) that are tolerant to substrate roughness is explored in this work. Traditional soft adhesives are designed by maintaining a balance between their cohesive strength and compliance. However, rough surfaces can significantly affect the adhesion strength of PSAs.

High Thermal Conductive Liquid Crystal Elastomer Nanofibers.

Liquid crystal elastomers (LCEs), consisting of polymer networks and liquid crystal mesogens, show a reversible phase change under thermal stimuli. However, the kinetic performance is limited by the inherently low thermal conductivity of the polymers. Transforming amorphous bulk into a fiber enhances thermal conductivity through the alignment of polymer chains.

Temperature- and Rate-Dependent Fracture in Disulfide Vitrimers.

The fracture behaviors of disulfide vitrimers are highly rate-dependent. Our investigation revealed that the temperature-dependent fracture behaviors of disulfide vitrimers cannot be entirely explained by a simple time-temperature superposition model. This Letter explores the impact of the dynamic nature of molecular defects on the temperature- and rate-dependent fracture behaviors of disulfide vitrimers.

Fracture mechanics modeling of aortic dissection.

Aortic dissection, a critical cardiovascular condition with life-threatening implications, is distinguished by the development of a tear and its propagation within the aortic wall. A thorough understanding of the initiation and progression of these tears, or cracks, is essential for accurate diagnosis and effective treatment. This paper undertakes a fracture mechanics approach to delve into the mechanics of tear propagation in aortic dissection.

Electrically active smart adhesive for a perching-and-takeoff robot.

Perching-and-takeoff robot can effectively economize onboard power and achieve long endurance. However, dynamic perching on moving targets for a perching-and-takeoff robot is still challenging due to less autonomy to dynamically land, tremendous impact during landing, and weak contact adaptability to perching surfaces. Here, a self-sensing, impact-resistant, and contact-adaptable perching-and-takeoff robot based on all-in-one electrically active smart adhesives is proposed to reversibly perch on moving/static dry/wet surfaces and economize onboard energy.

Electrowetting of a Soft Elastic Gel.

A liquid drop may change its wettability on a surface with an applied voltage, known as electrowetting. Herein, we report an electrowetting phenomenon of a soft elastic gel, where gel elasticity plays an important role. We have designed experiments to measure the voltage-dependent adhesion energy between the gel and a metal electrode and proposed an electromechanical model for the electrowetting behavior of the gel.

Dynamic compression of soft layered materials yields tunable and spatiotemporally evolving surface patterns.

Soft layered systems buckling to form surface patterns has been widely studied under quasistatic loading. Here, we study the dynamic formation of wrinkles in a stiff-film-on-viscoelastic-substrate system as a function of impact velocity. We observe a spatiotemporally varying range of wavelengths, which display impactor velocity dependence and exceed the range exhibited under quasistatic loading.

A wearable cardiac ultrasound imager.

Continuous imaging of cardiac functions is highly desirable for the assessment of long-term cardiovascular health, detection of acute cardiac dysfunction and clinical management of critically ill or surgical patients. However, conventional non-invasive approaches to image the cardiac function cannot provide continuous measurements owing to device bulkiness, and existing wearable cardiac devices can only capture signals on the skin. Here we report a wearable ultrasonic device for continuous, real-time and direct cardiac function assessment.

Magnetic vitrimer-based soft robotics.

Magnetically responsive elastomers, consisting of elastomer embedded with magnetic particles, can produce fast and reversible actuation when subjected to a magnetic field. They have been extensively explored to construct versatile remotely controllable soft robots. Nevertheless, the magnetically induced actuation strain in elastomers is typically small, which limits its broad applications.

Highly robust and soft biohybrid mechanoluminescence for optical signaling and illumination.

Biohybrid is a newly emerging and promising approach to construct soft robotics and soft machines with novel functions, high energy efficiency, great adaptivity and intelligence. Despite many unique advantages of biohybrid systems, it is well known that most biohybrid systems have a relatively short lifetime, require complex fabrication process, and only remain functional with careful maintenance. Herein, we introduce a simple method to create a highly robust and power-free soft biohybrid mechanoluminescence, by encapsulating dinoflagellates, bioluminescent unicellular marine algae, into soft elastomeric chambers.

Cavitation induced fracture of intact brain tissue.

Nonpenetrating traumatic brain injuries (TBIs) are linked to cavitation. The structural organization of the brain makes it particularly susceptible to tears and fractures from these cavitation events, but limitations in existing characterization methods make it difficult to understand the relationship between fracture and cavitation in this tissue. More broadly, fracture energy is an important, yet often overlooked, mechanical property of all soft tissues.

Highly Durable and Tough Liquid Crystal Elastomers.

Liquid crystal elastomers (LCEs) are soft materials that exhibit interesting anisotropic and actuation properties. The emerging applications of thermally actuatable LCEs demand sufficient mechanical durability under various thermomechanical cycles. Although LCEs are tough at room temperature, they become very brittle at high temperature (above their actuation temperature), which can cause unexpected failure.

Electrospun liquid crystal elastomer microfiber actuator.

Fibers capable of generating axial contraction are commonly seen in nature and engineering applications. Despite the broad applications of fiber actuators, it is still very challenging to fabricate fiber actuators with combined large actuation strain, fast response speed, and high power density. Here, we report the fabrication of a liquid crystal elastomer (LCE) microfiber actuators using a facile electrospinning technique.

Force-dependent bond dissociation explains the rate-dependent fracture of vitrimers.

We investigate the rate-dependent fracture of vitrimers by conducting a tear test. Based on the relationship between the fracture energy and the thickness of vitrimer films, we, for the first time, obtain the intrinsic fracture energy and bulk dissipation of vitrimers during crack extension. The intrinsic fracture energy strongly depends on tear speed, and such dependence can be well explained by Eyring theory.

Soft pumps for soft robots.

A light and portable soft electro-pneumatic pump could power future soft robots.

3D Printing of Electrically Responsive PVC Gel Actuators.

Additive manufacturing of electrically responsive soft actuators is of great importance in designing and constructing novel soft robots and soft machines. However, there are very limited options for 3D-printable and electrically responsive soft materials. Herein, we report a strategy of 3D printing polyvinyl chloride (PVC) gel actuators that are electrically controllable.