Jens Michael Warmuth, group manager for functional safety and system reliability verification at Fraunhofer Institute for Integrated Circuits’ Engineering of Adaptive Systems Division, has written an interesting piece for Semiconductor Engineering.The article discusses the increasing importance of reliability and safety in electronic systems. As electronics become more ubiquitous, even in consumer items, failures can cause major disruptions. This is especially critical in automotive and other safety applications where failures could lead to loss of life.
The past approach of redundancy and over-engineering for reliability is costly and often infeasible given size and space constraints. A better solution in many cases is failure prediction through damage detection. This involves determining the failure mechanisms and modes and how quickly they progress. Then methods are needed to automatically detect damage and provide notifications before failure occurs.
First, it is challenging to establish clear mappings between specific mechanical damage and resulting functional failures or failure modes. The same failure mechanism can cause different failure modes, while a given failure mode may stem from multiple failure mechanisms. Determining these interrelationships is an initial obstacle.
Second, once failure modes and mechanisms are understood, methods must be developed to automatically detect indications of damage. Ideal solutions would leverage existing functional components to act as sensors, rather than require dedicated additional hardware. Finding techniques to implement low-cost automated damage detection presents another hurdle.
Third, damage progression rates must be analyzed to understand how rapidly various failure mechanisms advance toward failure modes. This enables predicting when failures are imminent based on damage detection. Quantifying these timelines adds complexity.
Fourth, automated analysis of sensor data and reliable user notifications are needed to act on damage detection. Developing robust platforms for these capabilities requires further effort.
Finally, the author advocates that widespread damage detection requires common standards across industries. However, ongoing work to establish shared standards remains a challenge. Which leads me to think about self-healing displays because managing electronics is one thing, but if a display, let’s say a critical one in a car, suffers any problems, fixing and replacing becomes a very difficult proposition, not to mention the threat to passenger safety.
Self-Healing Electronics
There is a body of research on self-healing materials that can restore their properties after being damaged. It’s apparently something that Apple, Samsung, and LG are working on for smartphone displays, but if you do a scholarly search you’ll find that there are many approaches to the process.
The ability of of new materials that could be used in displays and other electronic devices to self-heal requires that the material itself work without an external detection system. Self-healing polymers (SHPs) can be categorized by:
- Extrinsic (use external healing agents) vs intrinsic (self-contained healing)
- Autonomic (self-triggered) vs non-autonomic (require external trigger)
- Thermosets, composites, covalent adaptable networks, or thermoplastics
Transparent SHPs have been used in flexible touch screens and display screens to promote self-healing. Back in 2019, researchers in the Department of Chemistry, Tsinghua University, Beijing, China, developed an artificial “electronic skin” material that was supposed to copy the transparent, stretchy, touch-sensitive, and self-healing properties of jellyfish skin.
The material they created was transparent, could conduct electricity, and self-heal both in and out of water. It was made from a stretchy fluorocarbon polymer mixed with a special liquid containing fluorine. By tweaking the liquid, the researchers controlled how well the material conducted electricity. It could also stretch up to 2000% its original size without breaking.
The researchers found that the material could self-heal quickly and repeatedly, even in wet, acidic or alkaline environments. This is because of interactions between the ions in the liquid and the polymer. To show possible uses, the researchers created touch, pressure and strain sensors from the electronic skin. They also printed stretchy circuit boards using the material.
So, it looks like the most likely short-term application of self-healing displays will be in smartphones, particularly foldables, where it makes the most sense. It’s a fascinating topic and one with enormous implications for the future of the industry.
References
- Cao, Y., Tan, Y.J., Li, S. et al. Self-healing electronic skins for aquatic environments. Nat Electron 2, 75–82 (2019). https://doi.org/10.1038/s41928-019-0206-5
- Cho, S. H., Lee, S. W., Hwang, I., Kim, J. S., Jeong, B., Kang, H. S., Kim, E. H., Kim, K. L., Park, C., Park, C., Advanced Optical Materials 2019, 7, 1801283. https://doi.org/10.1002/adom.201801283
- Chang, Y., Sun, J., Dong, L., Jiao, F., Chang, S., Wang, Y., Liao, J., Shang, Y., Wu, W., Qi, Y., & Shan, C.-X. (2022). Self-powered multi-color display based on stretchable self-healing alternating current electroluminescent devices. Nano Energy, 95, 107061. https://doi.org/10.1016/j.nanoen.2022.107061
