Fumio Narita

In the coming era of the internet of things (IoT), wireless sensor networks that monitor, detect, and gather data will play a crucial role in advancements in public safety, human healthcare, industrial automation, and energy management. Batteries are currently the power source of choice for operating wireless network devices due to their ease of installation; however, they require periodic replacement due to capacity limitations. Within the scope of the IoT, battery maintenance of the trillion s

Abstract The spread of the severe acute respiratory syndrome coronavirus has changed the lives of people around the world with a huge impact on economies and societies. The development of wearable sensors that can continuously monitor the environment for viruses may become an important research area. Here, the state of the art of research on biosensor materials for virus detection is reviewed. A general description of the principles for virus detection is included, along with a critique of the e

Abstract As society advances, the shift from passive medical care to health management and preventive medical care has become an important issue, with the realization of wearable monitors becoming desirable. In light of the COVID‐19 pandemic, the number of patients who are in urgent need of the monitoring of biological information is increasing. This review focuses on piezoelectric materials and composites that convert kinetic energy into electrical energy to realize self‐powered wearable monito

Based on the dynamic theory of linear piezoelectricity, we investigate the scattering of Love waves by a surface-breaking crack in a layered piezoelectric solid. The piezoelectric layer is perfectly bonded to a half-space of a different elastic solid and the crack is normal to the free surface. Both cases of a partially broken layer and a completely broken layer are studied. By the use of Fourier transform techniques, the mixed boundary value problem is reduced to a singular integral equation. T

Wearable Internet of Things devices require innovatively designed electromagnetic materials and energy harvesting technology that is lightweight and able to withstand vigorous exercise and impact. In this study, magnetostrictive wire/polymer composites are developed for the first time by embedding Fe–Co wires in an epoxy matrix, and their inverse magnetostrictive characteristics are studied. The output voltage of this novel composite due to compression dramatically increases with increasing stre

The inverse magnetostrictive effect is an effective property for energy harvesting; the material needs to have large magnetostriction and ease of mass production. Fe-Co alloys being magnetostrictive materials have favorable characteristics which are high strength, ductility, and excellent workability, allowing easy fabrication of Fe-Co alloy fibers. In this study, we fabricated magnetostrictive polymer composites, in which Fe-Co fibers were woven into polyester fabric, and discussed their sensor

The Villari effect of magnetostrictive materials, a change in magnetization due to an applied stress, is used for sensor/energy harvesting applications. In this work, magnetostrictive fiber/polymer composites are fabricated for the first time by embedding strong textured Fe–Co fibers in an epoxy matrix, and their stress-rate dependent output voltage characteristics are investigated. Compression tests are first conducted to measure the output voltage of a sample. A simple magnetomechanical coupli

Following the theory of linear piezoelectricity, we consider the electroelastic problem for a piezoelectric layer with a crack bonded to two elastic half planes under antiplane shear loading. The crack parallel to the interfaces is in the mid-plane of the piezoelectric layer. Fourier transforms are used to reduce the problem to the solution of a pair of dual integral equations. The solution of the dual integral equations is then expressed in terms of a Fredholm integral equation of the second ki