Writing messages underwater using new display technology

This breakthrough technology allows for the writing and erasing of messages underwater, marking a pivotal advancement in optical communication methods. Led by Professor Sei Kwang Hahn and PhD candidate Seong-Jong Kim from the Department of Materials Science and Engineering, the team's work focuses on the intriguing optical properties of ALPs, specifically in relation to mechanoluminescence (ML) and mechanical quenching (MQ).

ALPs are distinguished by their ability to absorb energy and then gradually release it, exhibiting mechanoluminescence when subjected to external physical stress, and experiencing mechanical quenching as the emitted light dims. The underlying mechanisms of these phenomena, which hold considerable promise for various technological applications, including optical displays, have hitherto been poorly understood.

The research, which has been published in Advanced Functional Materials journal, explores the roles of trapped electrons and the process of recharging in both mechanoluminescence and quenching. By elucidating these mechanisms, the POSTECH team has crafted an innovative optical display technology. They integrated ALPs with a thin layer of polymeric material, specifically PVDF-HFP, to create a unique optical display patch that can be adhered to the skin.

This patch allows users to convey information by applying a minimal amount of pressure with their finger, akin to writing. Exposure to ultraviolet light resets the display, effectively erasing the written content as one would erase a drawing from a sketchbook. Remarkably, this display patch is resistant to humidity and remains operational even when immersed in water for extended periods, representing a significant technological leap for communication tools in challenging environments such as underwater or areas with high humidity.

Professor Hahn highlighted the potential applications of this technology, suggesting its utility as a communication tool in environments where traditional methods are untenable, as well as its prospective use in wearable photonic biosensors and phototherapy systems that operate in extreme conditions.

The development of this technology was supported financially by the Basic Research Program, the Korea Medical Device Development Fund, the Biomedical Technology Development Program of the National Research Foundation of Korea, and POSCO Holdings. This breakthrough not only opens new avenues for underwater communication and wearable health technologies but also underscores the importance of fundamental research in unlocking new applications for existing materials.