In the present study, a stretchable hybrid film electrode composed of carbon nanotube (CNT) and styrene-butadiene-styrene block copolymer (SBS) was described. With certain tensile loading, the stretchable electrode will elongate. The as-prepared electrode could keep conductivity when the tensile strain is up to 20%. The resistivity of the stretchable electrode changes slowly and linearly with the elongation, showing that the electrode is suitable to be used as flexible and stretchable electrochemical platforms. Glucose is chosen as a model analyte to measure the electrochemical properties of the corresponding biosensor. The glucose biosensor could keep 86% of its responding signal in one month, showing significant long-term stability. The prepared stretchable biosensor is suitable to be equipped on new generation of wearable devices which can track the biochemistry signals such as sweat glucose, cholesterol and lactate, etc.
Structures with multiple deformation paths provide a promising platform for robotics and reprogrammable mechanical and thermal deformation materials. Reconfigurations with a multi-path can fulfill many tasks (e.g., walking and grasping) and possess multiple properties (e.g., targeted Poisson’s ratio and thermal expansion coefficient). Here, we proposed a new ring-like kirigami structure and theoretically and experimentally found that for a basic unit, there are four discrete deformation patterns and a continuous shearing deformation pattern; thus, there are a large number of discrete deformation patterns for a multi-unit combination with geometrical compatibility coupled with a shearing deformation mode. Moreover, targeted Poisson’s ratios (either + or -) in the x- and y-directions can be realized by inversely designing the geometrical parameters for a certain deformation path. Additionally, we showed the capability of constructing 2D and 3D cellular structures in various patterns with the proposed ring-like units. The multiple deformation modes demonstrated here open up avenues to design new reprogrammable materials and robots across various scales.
Mechanical computation outperforms electrical computation in applications under extreme conditions. Currently, logic gates can be constructed with mechanical metamaterials, but this may require complex architectures and computing rules, and more complex computations based on these gates are considerably more challenging. Mechanical computing systems with multistability cannot return to their initial stable states, which are hardly reused. Moreover, providing digital electrical outputs is useful to communicate with electrical systems. To address these issues, mechanical metamaterials can be integrated in a manner that is similar to a circuit network with a powerful computing capability. Herein, a general method that combines soft convex and concave modules, rigid frames, and conductive materials in one system to realize logic gates, addition, and multiplication is proposed. The soft modules make or break electrical connections with adjacent frames due to the presence or absence of compressive forces, operating as open and closed switches. Connections and disconnections between modules and frames can be demonstrated with conductive materials and LEDs. The proposed mechanism is simple, versatile, and reusable, allowing soft mechanical metamaterial units to carry out complex computations. The approach may improve the capabilities of soft robots, robotic materials, and microelectromechanical systems.
To understand the different roles played by sheet solids and network solids in complex porous biomaterials/native tissues, we designed a new kind of nature-inspired structure comprising these two solids by using triply periodic minimal surfaces and Voronoi diagrams using the CAD method and compared them with the previously reported Poisson-Voronoi (PV) solids that only comprise network solids. Here, we show that the sheet solids contribute greater stiffness and solid/void interface than the network solids, and our TPMS-Voronoi solids can improve/tune both the elastic moduli and specific surfaces even at fixed solid volume fraction and can be stiffer than the Poisson-Voronoi solids. This can directly guide the porous materials design for use in tissue engineering and aerospace.
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