The significantly enhanced energy storage characteristics of 0.5Ba(Zr0.2Ti0.8)O3–0.5(Ba0.7Ca0.3)TiO3 nanofibers/PVDF dielectric composites with low doping ratios and large aspect ratio nanofillers.

We report the preparation of amorphous CaCu 3 Ti 4 O 12 /polyimide (a-CCTO/PI) hybrid films for the first time.It was found that a relatively high dielectric permittivity, low loss and low conductivity were simultaneously achieved in the a-CCTO/PI films. Compared with the PI matrix and the CCTO/PI film with a 10 vol% concentration of CCTO, the dielectric permittivity of the a-CCTO/PI film with a 3 vol% concentration of a-CCTO increased by 29% and 16%, respectively. Interfacial polarization relaxation mainly determines the properties of a-CCTO/PI films, and this can guide the future preparation of ceramic-polymer composites. All the above-mentioned properties are beneficial for the use of a-CCTO/PI hybrid films in the electronics industry, for applications such as printed circuit boards (PCBs).

Implantable sensors that detect biomarkers in vivo are critical for early disease diagnostics. Although many colloidal nanomaterials have been developed into optical sensors to detect biomolecules in vitro, their application in vivo as implantable sensors is hindered by potential migration or clearance from the implantation site. One potential solution is incorporating colloidal nanosensors in hydrogel scaffold prior to implantation. However, direct contact between the nanosensors and hydrogel matrix has the potential to disrupt sensor performance. Here, we develop a hollow-microcapsule-based sensing platform that protects colloidal nanosensors from direct contact with hydrogel matrix. Using microfluidics, colloidal nanosensors were encapsulated in polyethylene glycol microcapsules with liquid cores. The microcapsules selectively trap the nanosensors within the core while allowing free diffusion of smaller molecules such as glucose and heparin. Glucose-responsive quantum dots or gold nanorods or heparin-responsive gold nanorods were each encapsulated. Microcapsules loaded with these sensors showed responsive optical signals in the presence of target biomolecules (glucose or heparin). Furthermore, these microcapsules can be immobilized into biocompatible hydrogel as implantable devices for biomolecular sensing. This technique offers new opportunities to extend the utility of colloidal nanosensors from solution-based detection to implantable device-based detection.

The high-performance energy-storage dielectric capacitors are increasingly necessary for the development of miniaturization, integration, and multifunctionality of electronic devices. Here, we describe a new strategy of a sandwich-structured polymer-based dielectric composite with inorganic fillers of semiconductor@perovskite hybrid fibers, and this novel dielectric composite possesses an excellent energy-storage performance at low electric field. It is of crucial importance to achieve hybrid nanofibers of 0.5Ba­(Zr0.2Ti0.8)­O3–0.5­(Ba0.7Ca0.3)­TiO3 nanofibers (BZT–BCT NFs) deposited by CoFe2O4 nanoparticles (CFO; hereafter, CFO@BZT–BCT NFs in short). Herein, the BZT–BCT NF ceramic has the typical perovskite structure and large dielectric constant, which is used as the ceramic-support for CFO. Meanwhile, the semiconductor of CFO works as the electron donor to offer a great interfacial polarization for the improvement of overall dielectric constant of the composite. Remarkably, the trilayer structure is composed of outer poly­(vinylidene fluoride) (PVDF) layer to improve the breakdown strength and middle CFO@BZT–BCT NFs–PVDF nanocomposite to enhance the dielectric properties. The BZT–BCT NFs were prepared by electrospinning, and then the CFO@BZT–BCT NFs were gained by hydrothermal method. Furthermore, the BZT–BCT NFs and the CFO@BZT–BCT NFs were modified by polydopamine (PDA). Finally, the sandwich-structured composites were gotten by a typical process of solution-casting and hot-pressing. The influences of fillers’ volume fraction and type on the performances of composites have been systematically investigated. The PVDF/CFO@BZT–BCT NFs–PVDF/PVDF composite (P/CFO@BZT–BCT NFs–P/P) exhibits an outstanding energy density performance under a low electric field. The trilayer structure composite with an optimized content of nanofibers possesses an excellent dielectric performance (dielectric constant ∼20.1 at 100 Hz) and great energy-storage performance (electric displacement ∼10.7 μC/cm2, discharged energy density ∼11.3 J/cm3, and efficiency ∼55.5% at a low electric field of 350 kV/mm). This work paves the way for potential applications in integrated electronic devices.