Guanghui Wang

Featuring non-contact, high-precision, and multi-material deposition, inkjet and related printing technologies offer a new alternative technique for plant systems. However, the spatial heterogeneity, continuous growth, and sensitivity of plant tissues to external perturbations make it difficult for conventional methods to target specific sites on living organs. This review evaluates thermal and piezoelectric inkjet printing, together with aerosol jet and electrohydrodynamic printing for plant applications. Moreover, it relates the jetting behavior of the printhead to interfacial processes between droplets and plant surfaces. Practical performance is assessed across four dimensions: effective feature size, organ-scale throughput, potential biological damage, and the physiological compatibility of printing inks with plants. Applications are then organized within a framework comprising five tiers: monitoring, delivery, sensing, biofabrication, and intelligent systems. Specifically, recent studies have demonstrated that these printing approaches can be employed for surface labeling and growth tracking of plant organs, localized delivery of agricultural inputs, fabrication of flexible sensors, and construction of living materials (e.g., plant cells). Combined with artificial intelligence technology, these capabilities could form a closed-loop system spanning sensing to feedback, with printing as the precision actuator, potentially shifting plant management from passive observation to active regulation. Finally, this review discusses the challenges of living-interface dynamics, ink biocompatibility, multiscale integration, and data intelligence. It further outlines the prospects of these technologies for programmable plants and living agricultural interfaces. By bridging printing technologies, plant systems, and functional biofabrication, this review provides a unified framework to guide the development of intelligent and sustainable agricultural systems.

Severe surface wear serves as a critical factor that limits the service life and operational reliability of precision mechanical components, whereas protective coatings offer an effective approach to mitigate surface wear and prolong the service life of mechanical parts. Although multiple studies focus on Cr-based coatings, the systematic correlation between coating microstructure and tribological properties remains unclear. Herein, Cr, CrN, CrN/Cr multilayer, and gradient CrN coatings are deposited on CrNi3MoVA steel by arc ion plating, and their tribological behaviors are systematically evaluated through sliding tests, three-dimensional wear-track profilometry, and SEM/EDS characterization. The results reveal a pronounced dependence of wear resistance on coating architecture, with the gradient CrN coating exhibiting the most stable and uniform wear behavior with the lowest material loss during sliding service. The superior wear resistance stems from the gradual compositional and microstructural transition from metallic Cr to ceramic CrN, which achieves uniform stress transfer, alleviates stress concentration, and suppresses crack initiation and damage propagation. The wear mechanism of the gradient CrN coating is dominated by mild adhesive wear, accompanied by slight tribo-oxidation, interfacial material transfer and minor third-body abrasive wear. This study demonstrates that gradient structure design provides an effective strategy for improving the structural stability and tribological durability of Cr-based coatings and offers a promising approach for surface wear protection and service life extension of precision mechanical components.

Chromium nitride (Cr-N) coatings fabricated by physical vapor deposition (PVD) have gained significant interest in the field of surface protection with the exceptional hardness, robust adhesion to substrates, and superior wear resistance. The mechanical properties of Cr-N coatings are predominantly determined by their chemical composition, phase structure, and microstructure. The selection of deposition technique and regulation of process parameters, such as N₂ flow rate, play a crucial role in optimizing coating performance. This review systematically summarizes recent research advancements in PVD-fabricated Cr-N coatings with a specific focus on both monolayer and multilayer architectures. It explores the impact of process parameters on the hardness, adhesion strength, and tribological properties. Furthermore, it outlines the design strategies and fabrication methodologies for high-performance Cr-N coatings. Results indicate that the mechanical properties of monolayer Cr-N coating are primarily governed by the process parameters. As for multilayer coatings, the incorporation of ductile Cr layers can enhance the coating-substrate adhesion strength and wear resistance while preserving a relatively high hardness. This study aims to provide a theoretical foundation and technical reference for future research and applications of the Cr-N coating material system.