In recent years, the development of electronic skin and smart wearable body sensors has put forward high requirements for flexible pressure sensors with high sensitivity and large linear measuring range. However, it turns out to be difficult to increase both of them simultaneously. In this paper, a flexible capacitive pressure sensor based on a porous carbon conductive pastepolydimethylsiloxane composite is reported, the sensitivity and the linear measuring range of which were developed using multiple methods including adjusting the stiffness of the dielectric layer material, fabricating a microstructure and increasing the dielectric permittivity of the dielectric layer. The capacitive pressure sensor reported here has a relatively high sensitivity of 1.1 kPa −1 and a large linear measuring range of 10 kPa, making the product of the sensitivity and linear measuring range 11, which is higher than that of the most reported capacitive pressure sensors to our best knowledge. The sensor has a detection of limit of 4 Pa, response time of 60 ms and great stability. Some potential applications of the sensor were demonstrated, such as arterial pulse wave measuring and breath measuring, which shows it as a promising candidate for wearable biomedical devices. In addition, a pressure sensor array based on the material was also fabricated and it could identify objects in the shape of different letters clearly, which shows promising application in future electronic skins.

Electronic skin (e‐skin) integrating pressure sensors and strain sensors has shown great potential applications in smart robotics and healthcare monitoring for their flexibility and wearability. However, making the sensor low cost and highly durable for industrialization and commercialization is still a problem to be addressed. An embedded 3D printing technology is developed based on novel thermosetting printing ink which is prepared using the Ecoflex and carbon nanoparticles. The properties of the printing ink including printability and electrical conductivity are first studied and then optimized. By using this technology, a glove‐shaped e‐skin integrating both strain sensors and pressure sensors is fabricated, and the properties of the sensors are studied. Both types of sensors have excellent stability and reliability which are verified by multiple long‐term measurements (10 000 testing cycles). Specifically, the sensors possess a great shock resistance and high durability which are significant for application in real life. Furthermore, some applications for human activity monitoring and personal healthcare are demonstrated, including complex gesture recognition using 15 strain sensors, hardness sensing using pressure sensors coupled with strain sensors, and arterial pulse measurement using pressure sensors, which are promising for smart robotic sensing and wearable biomedical devices.

This paper reports a novel microarray chip for in-situ, real-time and selective electroporation on individual cells integrated with cell positioning and impedance monitoring. An array of quadrupole-electrode units (termed positioning electrodes) and pairs of planar center electrodes located at the centers of each quadrupole-electrode unit were fabricated on the chip. The positioning electrodes are used to trap and position living cells onto the center electrodes based on negative dielectrophoresis (nDEP). The center electrodes are used for in-situ cell electroporation, and also used to measure cell impedance for monitoring cellular dynamics in real time. Controllably selective electroporation and electrical measurement on the cells in array are realized. We present an evidence of selective electroporation through use of fluorescent dyes. Subsequently we use in-situ and real-time impedance measurement to monitor the process, which demonstrates the dynamic behavior of the cell electroporation. Finally, we show the use of this device to perform successful transfection onto individual HeLa cells with vector DNA encoding a green fluorescent.

This paper presents a novel microarray chip integrating cell positioning with in situ, real-time and long-time impedance measurement on a single cell. The microchip integrates a plurality of quadrupole-electrode units (termed positioning electrodes) patterned into an array with pairs of planar electrodes (termed measuring electrodes) located at the centers of each quadrupole-electrode unit. The positioning electrodes are utilized to trap and position living cells onto the measuring electrodes based on negative dielectrophoresis (nDEP), while the measuring electrodes are used to measure impedances of the trapped single cells. Each measuring electrode has a small footprint area of 7 × 7 μm(2) to ensure inhabiting only one single cell on it. However, the electrode with a small surface area has a low double-layer capacitance when it is immersed in a liquid solution, thus generating a large double-layer impedance, which reduces the sensitivity for impedance measurement on the single cell. To enlarge the effective surface areas of the measuring electrodes, a novel surface-modification process is proposed to controllably construct gold nanostructures on the surfaces of the measuring electrodes while the positioning electrodes are unstained. The double layer capacitances of the modified electrodes are increased by about one order after surface-modification. The developed microchip is used to monitor the adhering behavior of a single HeLa cell by measuring its impedance spectra in real time. The measured impedance is analyzed and used to extract cellular electrical parameters, which demonstrated that the cell compresses the electrical double layer in the process of adherence and adheres onto the measuring electrodes after 4-5 hours.

Developing low-cost, high performance, stable non-noble bifunctional electrocatalysts for overall water splitting is of great importance for future energy supplement. Despite recent advances in the synthesis of transition metal selenide nanostructures, the fabrication of porous nanosheet based binder-free electrode with more active sites remains a major challenge. Herein, the self-templating construction of a porous CoSe2 nanosheet array on carbon cloth (p-CoSe2/CC) has been reported by vapor selenizing the preprepared α-Co­(OH)2 nanosheet array precursor. Arising from large active surface area, fast diffusion of generated gas and strong structural stability, the as-obtained p-CoSe2/CC can serve as an efficient bifunctional electrocatalyst for both OER and HER in alkaline electrolyte, with a current density of 10 mA cm–2 at overpotential of 243 mV for OER and 138 mV for HER, respectively. Moreover, when p-CoSe2/CC is assembled as an alkaline electrolyzor, it only needs a cell voltage of 1.62 V at 10 mA cm–2 and shows excellent long-term stability of 20 h. The versatile fabrication strategy with self-templated porous structure proves a new way to construct other advanced metal selenide for energy conversion and storage.