Carbon fiber reinforced polymer (CFRP) plays an important role in many fields, especially in aviation and civil industries. The electrical conductivity of CFRP is critical for its electrical behavior, such as its lightning strike vulnerability, electromagnetic shielding ability, and potential uses for self-sensing. In addition, the electrical conductivity is related to the mechanical integrity. Therefore, electrical properties can be measured as an indication when detecting delamination and other defects in CFRP. This review provides a comprehensive basis for readers to grasp recent research progresses on electrical behaviors of CFRP.

Metallic wires are used in many industrial applications, where the diameter and conductivity are key parameters to be measured. In eddy currents testing, the inductance of the sensor is affected by both the diameter and conductivity of sample wire. Consequently, wire diameter and conductivity cannot be determined from a single inductance measurement. In this paper, a novel combined inductive and capacitive sensor is designed, in which the diameter can be inversed from the capacitance measurement of the sensor. Based on the diameter value, the inductance measurement can be used to accurately determine the conductivity of the wires using a look-up table approach. In addition, a model for a wire inside of the capacitive sensor is derived. Measurements have been carried out for 16 samples and the results have verified the proposed approach. This technique could contribute to real-time in-situ quality control of wire + arc additive manufacture processes.

Wearable sensor technologies attract increasing attention for continuous monitoring of human health. Much effort is devoted to exploit well‐designed materials to realize superior abilities, such as high sensitivity, stability, and responsiveness. However, it hardly meets huge demands for practically wearable applications simply focusing on the development of sensing materials in isolation. Comprehensive consideration is given from upstream materials to endure market, including materials design, sensor assembly, signal analysis, theoretical foundation, and final system performance, such as sensitivity, stability, responsiveness, cost, comfortability, and durability. Herein, a systematic design is presented that combines a conductive fiber fabrication based on surface nanotechnology, device assembly process optimization, signal acquisition and analysis, and theoretical simulation, through a new multidisciplinary strategy integrating material science, textile technology, electromagnetics, and electronic engineering. The as‐constructed magnetic inductance sensing system shows approximately six‐times inductance change with regard to joint bending motions during rehabilitation exercises. This integrated design strategy offers a new concept, namely, a whole sensing system design, for wearable technologies in real‐time health monitoring applications.

Metallic waste classification benefits the environment, resource reuse and industrial economy. This paper provides a fast, non-contact and convenient method based on eddy current to classify metals. The characteristic phase to characterize different conductivity is introduced and extracted from mutual inductance in the form of amplitude and phase. This characteristic phase could offer great separation for non-tilting metals. Although it is hard to classify tilting metals by only using the characteristic phase, we propose the technique of phase compensation utilizing photoelectric sensors to obtain the rectified phase corresponding to the non-tilting situation. Finally, we construct a classification algorithm involving phase compensation. By conducting a test, a $95\%$ classification rate is achieved.

The classification of conductivity is significant for recycling metallic scraps. The eddy current sensor is distinct from other classification methods by its merits of non-contact, economical set-up, fast measuring, and so forth. By introducing a set-up that could ensure the single-valued mutual inductance trajectory on the complex plane, we propose the circle fitting method to extract the global features of different trajectories. It is subsequently observed that the fitting circle centers-one of the global features-for the same conductivity with various tilting angles are distributed longitudinally close to each other. The feature line, which is parallel to the abscissa axis, is introduced to represent this gathering distribution behavior. The feature lines for different conductivity are distinguishable. Thus, we construct a simple classification method with only two steps. The test results show great fidelity of the proposed classification technique which can successfully classify the tilting metallic samples within 11.3°.

In article number 1900037, Xuqing Liu, Wuliang Yin, and co‐workers propose a systematic design of magnetic induction sensor, involving materials preparation via new surface nanotechnology, assemble process optimization by waxing, signal acquisition and analysis via novel equipment, and theoretical considerations in electromagnetics to support joint rehabilitation motion results.