Monolayer nano-sphere arrays attract great research interest as they can be used as templates to fabricate various nano-structures. Plasma etching, and in particular high-frequency plasma etching, is the most commonly used method to obtain non-close-packed monolayer arrays. However, the method is still limited in terms of cost and efficiency. In this study, we demonstrate that a low frequency (40 kHz) plasma etching system can be used to fabricate non-close-packed monolayer arrays of polystyrene (PS) nano-spheres with smooth surfaces and that the etching rate is nearly doubled compared to that of the high-frequency systems. The study reveals that the low-frequency plasma etching process is dominated by a thermal evaporation etching mechanism, which is different from the atom-scale dissociation mechanism that underlines the high-frequency plasma etching. It is found that the polystyrene nano-sphere size can be precisely controlled by either adjusting the etching time or power. Through introducing oxygen as the assisting gas in the low frequency plasma etching system, we achieved a coalesced polystyrene nano-sphere array and used it as a template for metal-assisted chemical etching. We demonstrate that the method can significantly improve the aspect ratio of the silicon nanowires to over 200 due to the improved flexure rigidity.

At present, the situation of air pollution is still serious, and research on air filtration is still crucial. For the nanofiber air filtration membrane, the diameter, porosity, tensile strength, and hydrophilicity of the nanofiber will affect the filtration performance and stability. In this paper, based on the far-field electrospinning process and the performance effect mechanism of the stacked structure fiber membrane, nanofiber membrane was prepared by selecting the environmental protection, degradable and pollution-free natural polysaccharide biopolymer pullulan, and polyvinylidene fluoride polymer with strong hydrophobicity and high impact strength. By combining two kinds of fiber membranes with different fiber diameter and porosity, a three-layer composite nanofiber membrane with better hydrophobicity, higher tensile strength, smaller fiber diameter, and better filtration performance was prepared. Performance characterization showed that this three-layer composite nanofiber membrane had excellent air permeability and filtration efficiency, and the filtration efficiency of particles above PM 2.5 reached 99.9%. This study also provides important reference values for the preparation of high-efficiency composite nanofiber filtration membrane.

Event-triggered optimal stabilization problem is investigated for macro-micro composite stage system with dynamical perturbation and interconnections. By using a novel cost function and considering the interconnected subsystems as a whole system, stabilization problem of the unknown interconnected system converts to control problem with optimality for the corresponding nominal system. On the side, the update frequency of the controller can effectively be decreased by employing an event-triggered condition. Furthermore, an optimal controller is derived by solving the modified Hamilton-Jacobi-Bellman (HJB) equation via single critic NN with asymptotically stable structure. And then the uniformly ultimately bounded (UUB) stability issue of closed-loop system is analyzed. Finally, the effectiveness of the developed event-triggered stabilization control scheme is verified by using simulation results for macro-micro composite stage system.

Template matching has been widely used in visual inspection process of WLFC packaging, but the structures of traditional TM algorithms always are direct feed-forward, which leads to the fact that it is very hard to achieve fast speed and high accuracy at the same time. The motivation of this work is to combine the ability to enable the chip visual measurement running in fast speed and high accuracy manner. Firstly, a novel self-feedback intelligent template matching structure is proposed, which can enable the intermediate information in the matching process to be fully utilized. The intelligent speed and resolution regulation rules are combined to construct the SFI-TM algorithm. Then, the reliability and robustness of the algorithm is analyzed to make sure it works stable. Finally, the practical chip alignment visual inspection experiments including parameter testing, comparing experiments with the other proposed visual detection algorithms, and robustness testing are carried out.

In this paper, we synergistically combine electrohydrodynamic (EHD) printing and replica molding for the fabrication of microlenses. Glycerol solution microdroplets was sprayed onto the ITO glass to form liquid mold by an EHD printing process. The liquid mold is used as a master to fabricate a polydimethylsiloxane (PDMS) mold. Finally, the desired micro-optical device can be fabricated on any substrate using a PDMS soft lithography mold. We demonstrate our strategy by generating microlenses of photocurable polymers and by characterizing their optical properties. It is a new method to rapidly and cost-effectively fabricate molds with small diameters by exploiting the advantages of EHD printing, while maintaining the parallel nature of soft-lithography.