Individual strings of conducting carbon cones and discs in a polymer matrix: Electric field-induced alignment and their use as a strain sensor

Investigating the Electromechanical Properties of Carbon Black-Based Conductive Polymer Composites via Stochastic Modeling

Conductive polymer composites (CPCs) have shown potential for structural health monitoring applications based on repeated findings of irreversible transducer electromechanical property change due to fatigue. In this research, a high-fidelity stochastic modeling framework is explored for predicting the electromechanical properties of spherical element-based CPC materials at bulk scales. CPC dogbone specimens are manufactured via casting and their electromechanical properties are characterized via uniaxial tensile testing. Model parameter tuning, demonstrated in previous works, is deployed for improved simulation fidelity. Modeled predictions are found in agreement with experimental results and compared to predictions from a popular analytical model in the literature.

Directed Assembly of Particles for Additive Manufacturing of Particle-Polymer Composites

Particle-polymer dispersions are ubiquitous in additive manufacturing (AM), where they are used as inks to create composite materials with applications to wearable sensors, energy storage materials, and actuation elements. It has been observed that directional alignment of the particle phase in the polymer dispersion can imbue the resulting composite material with enhanced mechanical, electrical, thermal or optical properties. Thus, external field-driven particle alignment during the AM process is one approach to tailoring the properties of composites for end-use applications. This review article provides an overview of externally directed field mechanisms (e.g., electric, magnetic, and acoustic) that are used for particle alignment. Illustrative examples from the AM literature show how these mechanisms are used to create structured composites with unique properties that can only be achieved through alignment. This article closes with a discussion of how particle distribution (i.e., microstructure) affects mechanical properties. A fundamental description of particle phase transport in polymers could lead to the development of AM process control for particle-polymer composite fabrication. This would ultimately create opportunities to explore the fundamental impact that alignment has on particle-polymer composite properties, which opens up the possibility of tailoring these materials for specific applications.

Solution processed membrane-based wearable ZnO/graphene Schottky UV photodetectors with imaging application

Flexible and wearable electrical devices have attracted extensive research attention in recent years. In the device fabrication process, the low-cost and compatibility with industrialized mass production are of great importance. Herein, membrane-based flexible photodetectors (PDs) based on Polyvinylidene Fluoride filter membrane with the structure of Ag nanowires (NWs)/ZnO NWs/graphene were fabricated by a full-solution method. The built-in electric field due to the ZnO/graphene Schottky junction is in favor of the separation and transport of photo-generated carriers, leading to enhanced device performance. The I _light/I _dark ratio was as high as ∼10², which is far superior to that of the reported ZnO-based fiber-shaped PDs. The PDs with remarkable flexibility can be easily attached to the human body and even can work steadily under serious bending conditions. Particularly, the photocurrent can keep 95% of the maximum value after the PD was bent 1000 times. In addition to the wearable applications, the membrane-based PD arrays can also be applied for imaging application.