This article reviews the existing work in selfhealing and self-repairing technologies, including work in software engineering, materials, mechanics, electronics, MEMS, self-reconfigurable robotics, and others. It suggests a terminology and taxonomy for self-healing and selfrepair, and discusses the various related types of other self-* properties. The mechanisms and methods leading to selfhealing are reviewed, and common elements across disciplines are identified.

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Autonomy has become a focal point for research and development in many industries. Whilst this was traditionally achieved by modelling self-engineering behaviours at the component-level, efforts are now being focused on the sub-system and system-level through advancements in artificial intelligence.Exploiting its benefits requires some innovative thinking to integrate overarching concepts from big data analysis, digitisation, sensing, optimisation, information technology, and systems engineering.With recent developments in Industry 4.0, machine learning and digital twin , there has been a growing interest in adapting these concepts to achieve autonomous maintenance; the automation of predictive maintenance scheduling directly from operational data and for in-built repair at the systems-level.However, there is still ambiguity whether state-of-the-art developments are truly autonomous or they simply automate a process.In light of this, it is important to present the current perspectives about where the technology stands today and indicate possible routes for the future. As a result, this effort focuses on recent trends in autonomous maintenance before moving on to discuss digital twin as a vehicle for decision making from the viewpoint of requirements, whilst the role of AI in assisting with this process is also explored.A suggested framework for integrating digital twin strategies within maintenance models is also discussed. Finally, the article looks towards future directions on the likely evolution and implications for its development as a sustainable technology.Click here to view linked References

We describe the novel fabrication of a 3D electrical small antenna and its subsequent characterization. The patterning of meander lines conformed onto a hemispherical substrate is achieved by 3D holographic photolithography, which uses time-division multiplexing of a series of iteratively optimized computer-generated holograms. The meander lines have a line width of 100 μm and line separation of 400 μm, with a line pitch of 500 μm and a total meander length of 145 mm. The working frequency is found to be 2.06 GHz, with an efficiency of 46%. This work demonstrates a new method for the fabrication of 3D conformal antennas.

Self-engineering systems that are capable of repairing themselves in-situ without the need for human decision (or intervention) could be used to achieve zero-maintenance. This philosophy is synonymous to the way in which the human body heals and repairs itself up to a point. This article synthesises issues related to an emerging area of self-healing technologies that links software and hardware mitigations strategies. Efforts are concentrated on built-in detection, masking and active mitigation that comprises self-recovery or self-repair capability, and has a focus on system resilience and recovering from fault events. Design techniques are critically reviewed to clarify the role of fault coverage, resource allocation and fault awareness, set in the context of existing and emerging printable/nanoscale manufacturing processes. The analysis presents new opportunities to form a view on the research required for a successful integration of zero-maintenance. Finally, the potential cost benefits and future trends are enumerated.

We present a novel lithographic process for patterning controlled-width tracks onto anisotropically micromachined silicon. The technique is based on the use of computer-generated holographic masks with a custom alignment and exposure tool. Experimental and simulation results are presented. 3D holographic photolithography significantly reduces the problem normally present with photolithography on non-planar surfaces-namely diffractive line broadening. A negative-acting electrodepositable photoresist (InterVia 3D-N) is used in the study. Its deposition onto the 3D substrate is optimized by modification of coating temperature and thickness and of pre-exposure bake conditions. We show the successful patterning of a constant-width 8 μm line down the sloping sidewall of a 500 μm thick silicon wafer. This is beyond the conventional resolution limit and indicates the potential of the technique for realizing high-density vertical routing in electronic packages and MEMS.

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