We herein report a facile molten-salt synthetic strategy
to prepare
transparent and uniform Li, Ba-doped (K,Na)NbO3 (KNN) single-crystal
microcuboids (∼80 μm). By controlling the degree of supersaturation,
different growth modes were found and the single-crystal microcuboids
were synthesized via island-like oriented attachment
of KNN particles onto the growing surface. The distinct relaxor ferroelectric
(RFE) properties were achieved in the single-crystal microcuboids,
which were different from the normal ferroelectric (FE) properties
found in their KNN ceramic counterparts prepared through a solid-state
reaction using the same initial precursors. The RFE properties were
realized by dislocation-induced nanodomain formation during oriented
attachment growth of single-crystal microcuboids, which is different
from the current strategies to derive the nanodomains by the local
compositional inhomogeneity or the application of an electric field.
The dislocations served as nucleation sites for ferroelectric domain
walls and block the growth of domains. The KNN single-crystal microcuboids
exhibited a higher effective piezoelectric coefficient (∼459
pm/V) compared to that of the bulk KNN ceramic counterpart (∼90
pm/V) and showed the broad diffuse maxima in the temperature dependence
dielectric permittivity. The high maximum polarization (69.6 μC/cm2) at a relatively low electric field (30 kV/cm) was beneficial
for energy storage applications. Furthermore, the KNN-based transparent,
flexible pressure sensor directly monitored the mechanical motion
of human activity without any external electric power. This study
provides insights and synthetic strategies of single-crystal RFE microcuboids
for other different perovskites, in which nanodomain structures are
primarily imposed by their chemical composition.
Since thermometry of human skin is
critical information that provides
important aspects of human health and physiology, accurate and continuous
temperature measurement is required for the observation of physical
abnormalities. However, conventional thermometers are uncomfortable
because of their bulky and heavy features. In this work, we fabricated
a thin, stretchable array-type temperature sensor using graphene-based
materials. Furthermore, we controlled the degree of graphene oxide
reduction and enhanced the temperature sensitivity. The sensor exhibited
an excellent sensitivity of 2.085% °C–1. The
overall device was designed in a wavy meander shape to provide stretchability
for the device so that precise detection of skin temperature could
be performed. Furthermore, polyimide film was coated to secure the
chemical and mechanical stabilities of the device. The array-type
sensor enabled spatial heat mapping with high resolution. Finally,
we introduced some practical applications of skin temperature sensing,
suggesting the possibility of skin thermography and healthcare monitoring.
The interest in biodegradable pressure sensors in the biomedical field is growing because of their temporary existence in wearable and implantable applications without any biocompatibility issues. In contrast to the limited sensing performance and biocompatibility of initially developed biodegradable pressure sensors, device performances and functionalities have drastically improved owing to the recent developments in micro-/nano-technologies including device structures and materials. Thus, there is greater possibility of their use in diagnosis and healthcare applications. This review article summarizes the recent advances in micro-/nano-structured biodegradable pressure sensor devices. In particular, we focus on the considerable improvement in performance and functionality at the device-level that has been achieved by adapting the geometrical design parameters in the micro- and nano-meter range. First, the material choices and sensing mechanisms available for fabricating micro-/nano-structured biodegradable pressure sensor devices are discussed. Then, this is followed by a historical development in the biodegradable pressure sensors. In particular, we highlight not only the fabrication methods and performances of the sensor device, but also their biocompatibility. Finally, we intoduce the recent examples of the micro/nano-structured biodegradable pressure sensor for biomedical applications.
Argyrodite solid electrolytes such as lithium phosphorus sulfur chloride (Li6PS5Cl) have recently attracted great attention due to their excellent lithium-ion transport properties, which are applicable to all-solid-state lithium batteries. In this study, we report the improved ionic conductivity of an argyrodite solid electrolyte, Li6PS5Cl, in all-solid-state lithium batteries via the co-doping of chlorine (Cl) and aluminum (Al) elements. Electrochemical analysis was conducted on the doped argyrodite structure of Li6PS5Cl, which revealed that the substitution of cations and anions greatly improved the ionic conductivity of solid electrolytes. The ionic conductivity of the Cl- and Al-doped Li6PS5Cl (Li5.4Al0.1PS4.7Cl1.3) electrolyte was 7.29 × 10−3 S cm−1 at room temperature, which is 4.7 times higher than that of Li6PS5Cl. The Arrhenius plot of the Li5.4Al0.1PS4.7Cl1.3 electrolyte further elucidated its low activation energy at 0.09 eV.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.