Effects of hot pressing (HP) on the dielectric and grain‐boundary characteristics of copper titanate (CaCu3Ti4O12 or CCTO) materials were studied with the comparison of conventionally prepared samples. HP at 1100°C in N2 atmosphere resulted in uniformly distributed smaller grain sizes and less Cu‐rich grain boundaries, without the accompanying secondary CuO phase. The high effective permittivity of ∼3 × 104 at 1 kHz, obtained in the HP sample having a relatively smaller grain size of ∼2.4 μm, is assumed to be associated with a higher dielectric constant of thinner grain‐boundary phases. The low grain‐boundary resistivities of 199–319 kΩ·cm in the HP samples are likely induced by the N2 atmosphere and less Cu‐rich grain‐boundary phase.

Wearable pressure sensors having versatile device structures have been extensively investigated to achieve high sensitivity under mechanical stimuli. Here, we introduce piezoelectric pressure sensors based on fabrics woven using polyvinylidene fluoride (PVDF) weft and polyethylene terephthalate (PET) warp yarns with different weave structures: 1/1 (plain), 2/2, and 3/3 weft rib patterns. The dependence of the pressure-sensing performance on the weave pattern is demonstrated with an actual large-scale fabric up to the ~2 m scale. An optimized pressure sensor with a 2/2 weft rib pattern produced a high sensitivity of 83 mV N−1, which was 245% higher than that of the 1/1 pattern. The detection performance of the optimal fabric was extensively evaluated with a variety of ambient input sources, such as pressing, bending, twisting, and crumpling, as well as various human motions. Further, a large all-fabric pressure sensor with arrayed touch pixel units demonstrated highly sensitive and stable sensing performance.

High dielectric constant (k) CaCu3Ti4O12 (CCTO) has been studied as a potential filler for low‐temperature cofired ceramics (LTCC) based on typical calcium aluminoborosilicate glass. CCTO does not appear to be chemically reactive with the glass regardless of the firing temperature over the compositional range of 30–90 wt% CCTO. Dielectric constant and dielectric loss turned out to depend strongly on the relative content of CCTO and firing temperature. As an optimal composition, the glass with 60 wt% CCTO exhibited a k∼32 and tan δ∼0.01 as a result of firing at 850°C, which is preferably applicable for the medium k LTCC applications. The higher content of 90 wt% CCTO needed to be densified at 900°C for better densification with a higher dielectric constant of ∼150. However, the 900°C firing was not acceptable for the 30 and 60 wt% CCTO‐containing samples due to the unexpected expansion of samples leading to significantly enlarged pores.

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BaTiO 3 -based dielectrics containing the selective additive combinations from Pb-free glasses and fluoride compounds such as AlF 3 , BaF 2 , CaF 2 , LiF and ZnF 2 were studied mainly for a potential N 2 -fireable embedded capacitor in printed circuit board with Cu metallization. The physical and dielectric properties, such as dielectric constant (k), loss tangent (tanδ) and T c , strongly depended on the choice of additive combination. A bismuth borosilicate glass was most promising in terms of the degree of densification and dielectric constant. The samples containing LiF and ZnF 2 and sintered at 950°C looked most beneficial in that these additives produced high k of >1,200 and low tanδ of < 0.022 at room temperature regardless of sintering atmosphere. As an example, the 95BaTiO 3 -2LiF-3(Bi borosilicate) sample exhibited k~1,340 and tanδ0.022 at room temperature when fired at 950°C in N 2 .