Using the shadowgraph technique, we performed direct measurements of the vapor density in the discharge channel of a pulsed positive streamer discharge in water. With this experimental technique, we quantitatively measured the vapor density in the discharge channel of a pulsed positive streamer discharge in water of conductivity 100 μS/cm. The results show that the vapor density in the discharge channel ranges from 100 to 660 kg/m3, and presents an increasing tendency along the axial direction of the discharge channel with increasing distance from the tip of the anode.

Hydrogels are the ideal materials in the development of implanted bioactive neural interfaces because of the nerve tissue-mimicked physical and biological properties that can enhance neural interfacing compatibility. However, the integration of hydrogels and rigid/dehydrated electronic microstructure is challenging due to the non-reliable interfacial bonding, whereas hydrogels are not compatible with most conditions required for the micromachined fabrication process. Herein, we propose a new enzyme-mediated transfer printing process to design an adhesive biological hydrogel neural interface. The donor substrate was fabricated via photo-crosslinking of gelatin methacryloyl (GelMA) containing various conductive nanoparticles (NPs), including Ag nanowires (NWs), Pt NWs, and PEDOT:PSS, to form a stretchable conductive bioelectrode, called NP-doped GelMA. On the other hand, a receiver substrate composed of microbial transglutaminase-incorporated gelatin (mTG-Gln) enabled simultaneous temporally controlled gelation and covalent bond-enhanced adhesion to achieve one-step transfer printing of the prefabricated NP-doped GelMA features. The integrated hydrogel microelectrode arrays (MEA) were adhesive, and mechanically/structurally bio-compliant with stable conductivity. The devices were structurally stable in moisture to support the growth of neuronal cells. Despite that the introduction of AgNW and PEDOT:PSS NPs in the hydrogels needed further study to avoid cell toxicity, the PtNW-doped GelMA exhibited a comparable live cell density. This Gln-based MEA is expected to be the next-generation bioactive neural interface.

To improve the current non-linear optically coupled isolation amplifier and high power consumption, we designed a low-power, high-speed and high-linearity BiCMOS optically isolation amplifier. There are only two push-pull output stages configuration bipolar transistor (BJT) in the design process, the rest of the circuit is the CMOS device. To improve amplifier gain linearity and stability, we introduce the complementary symmetrical photodiode, in the optically coupled part and every amplifier, negative feedback is introduced. Experimental results indicate that the design of optically isolation amplifier ± 3 dB bandwidth increases 40 kHz than optically isolation amplifier ISO100 bipolar, When the power supply voltage is 4.8 V, the delay - power product of DP is lower than ISO100 37.3 pJ, gain linearity is up to 5.5 × 10-5, which is suitable for high-speed control system.