Search

Achieving a high strain under a low electric field is critical for actuator applications, and so is something which has always been pursued. Here, an enhanced strain was achieved by introducing Sr0.7Bi0.2TiO3 (SBT) into Bi1/2(Na0.84K0.16)1/2TiO3 (BNKT) under the guidance of phase boundary engineering and domain design. The introduction of the SBT induces a phase transition from the dominant rhombohedral to the dominant tetragonal and strong relaxor behaviour, as well as increased ergodicity. The enhanced and anti-fatigue strain of 0.57% was obtained in BNKT-8SBT ceramics under a relatively low electric field of 50 kV cm−1, accompanied by a large of 1140 pm V−1. An atomic-resolution displacement vector map reveals the coexistence of R and T nanodomains induced by local structural inhomogeneity. The coexistent nanodomains contribute to a flexible domain structure. This unique domain structure is suggested to be the origin of the relaxor features and the enhanced strains. This result is helpful to understand the excellent performance from a structural point of view and could promote further development of high-performance materials. [ABSTRACT FROM AUTHOR]

Dielectric materials as capacitors with high energy storage performance have received substantial attention for applications as important components in modern electrical and electronic systems. Relaxor ferroelectrics, as one of the popular dielectric materials, have demonstrated extraordinary energy storage performance. However, the origin of this extraordinary performance is not fully understood due to the complex atomic structural heterogeneity. Here, aberration-corrected scanning transmission electron microscopy is employed to study the atomistic structure of a Sr0.7Bi0.2TiO3 lead-free relaxor ferroelectric thin film, which shows high energy density of 77.8 J cm−3, good energy efficiency of 67.8%, and high frequency, temperature and antifatigue stability simultaneously. A slush-like polar structure with 2–4 nm multi-domains and low-angle domain walls, rather than polar nanoregions, is observed, revealed and quantitively described in the Sr0.7Bi0.2TiO3 relaxor ferroelectric thin film. This slush-like polar structure is considered to enable flexible domain switching under an electric field, and is proposed as the mechanism for the high energy storage performance. These results benefit the understanding of the atomic-scale structure of relaxor ferroelectrics and provide guidance for the exploration of new relaxor ferroelectrics with high energy storage performance. [ABSTRACT FROM AUTHOR]

Stem cells have attracted increasing research interest in the field of regenerative medicine due to their unique abilities to differentiate into multiple cell lineages. Label-free, real-time, and long-term monitoring for stem cell differentiation is requisite in studying directional differentiation and development mechanisms for tissue engineering applications, but a great challenge because of the rigorous demands for sensitivity, stability and biocompatibility of devices. In this article, a label-free and real-time monitoring approach using a zinc oxide (ZnO) nanorod field effect transistor (FET) is proposed to detect cell traction forces (CTFs) exerted by cells on underlying substrates. The ZnO nanorod FET with the approach of difference-frequency lock-in detection achieves high sensitivity, good stability, and excellent biocompatibility, by which real-time and long-term (over 20 days) monitoring of cellular mechanical changes in osteogenic differentiation of mesenchymal stem cells (MSCs) is successfully achieved. We also employ electrical impedance monitoring using microelectrode array chips and microscopic observation to investigate cell migration and nodular aggregation behaviors of MSCs in osteogenic differentiation. Various biochemical assays including alkaline phosphatase (ALP), osteopontin expression and alizarin red staining are utilized to verify osteogenic differentiation of MSCs. We propose a combination of cell traction force measurement, impedance measurement and microscopic observation to provide multimodal profiling of cell morphology, and cellular biomechanical and electrophysiological phenotypes, which can track cellular dynamics in stem cell development and help to deeply understand the mechanism of osteogenic differentiation. [ABSTRACT FROM AUTHOR]

Electrical stimulation (ES) as an easy and effective inducing method has been widely used in induction differentiation of stem cells, e.g. osteogenic differentiation of mesenchymal stem cells (MSCs) for bone healing and bone tissue therapies. However, the micro-effect of an inhomogeneous electric field has rarely been investigated for ES in induction differentiation, and conventionally used ex situ assays may preclude accurate assessment due to variation from cell inoculation and treatments. Here, a novel electrical stimulation method with a microelectrode array chip is proposed for osteogenic differentiation of MSCs. The electric field applied onto the MSCs by the microelectrode array is designed similarly with a natural aggregation distribution of differentiated MSCs. The proposed ES method accelerates osteoblast proliferation and differentiation in the electrode array region and generates a larger amount of mineralized deposits, which are assayed via in situ alizarin red staining and morphology observation as well as immunocytochemistry. In addition, this method allows a direct in situ assessment to compare the osteogenic differentiation of MSCs with and without ES on a single chip to avoid culture environment difference. The method provides a fundamental platform for investigating induced differentiation of stem cells and allows integration with multifunctional cell assays to achieve in situ tracking for the differentiation process of stem cells. [ABSTRACT FROM AUTHOR]

High electrostability and long life-time of planar chip technology are crucial for electrophysiological measurements such as ionic current recording through ion channel proteins embedded in biological cell membrane. In this paper, we propose a novel planar microchip integrated with microelectrochemical cell array toward to a feasible solution for ion channel screening with high resolution and long life-time. In order to reduce the interference from the leakage currents, a synthetic lipid bilayer is applied to form a high sealing resistance. The whole-cell electrical access can be constructed via electroporating the lipid bilayer in close proximity to the cell membrane. Parameters of electroporation including amplitude and time scale are firstly optimized by using parallel electroporation to the lipid bilayers. In this approach, individual cells can be trapped to the target positions by applying dielectrophoresis (DEP) manipulation. Poly(ethylene glycol) (PEG) is employed with low concentration to facilitate the closed contact between the cells and the lipid bilayer to increase the efficiency of the whole-cell mode construction. Through this chip based method, stable current recordings through inward rectifier potassium (Kir) ion channels embedded in rat basophilic leukemia (RBL-1) cell membrane are achieved with high electrical sealing resistance (over 1 GΩ). In addition, without need for complex fluidic connections, this method allows for an easy operation and further miniaturization of the measuring system. [ABSTRACT FROM AUTHOR]

Retraction of 'Microelectrochemical cell arrays for whole-cell currents recording through ion channel proteins based on trans-electroporation approach' by Tianyang Zheng et al., Analyst, 2020, 145, 197–205. [ABSTRACT FROM AUTHOR]

Correction for 'Microelectrochemical cell arrays for whole-cell currents recording through ion channel proteins based on trans-electroporation approach' by Tianyang Zheng, et al., Analyst, 2020, DOI: 10.1039/c9an01737b. [ABSTRACT FROM AUTHOR]

High electrostability and long life-time of planar chip technology are crucial for electrophysiological measurements such as ionic current recording through ion channel proteins embedded in biological cell membrane. In this paper, we propose a novel planar microchip integrated with microelectrochemical cell array toward to a feasible solution for ion channel screening with high resolution and long life-time. In order to reduce the interference from the leakage currents, a synthetic lipid bilayer is applied to form a high sealing resistance. The whole-cell electrical access can be constructed via electroporating the lipid bilayer in close proximity to the cell membrane. Parameters of electroporation including amplitude and time scale are firstly optimized by using parallel electroporation to the lipid bilayers. In this approach, individual cells can be trapped to the target positions by applying dielectrophoresis (DEP) manipulation. Poly(ethylene glycol) (PEG) is employed with low concentration to facilitate the closed contact between the cells and the lipid bilayer to increase the efficiency of the whole-cell mode construction. Through this chip based method, stable current recordings through inward rectifier potassium (Kir) ion channels embedded in rat basophilic leukemia (RBL-1) cell membrane are achieved with high electrical sealing resistance (over 1 GΩ). In addition, without need for complex fluidic connections, this method allows for an easy operation and further miniaturization of the measuring system.