Scientists at the Technical University of Denmark have developed a new technique for attaching ultra-thin oxide membranes to flexible metallic supports, a breakthrough that could accelerate the development of wearable sensors, foldable displays, and flexible energy devices. The research shows that fragile crystalline oxide sheets can adhere strongly to specially prepared metallic surfaces while retaining their ability to bend and stretch, overcoming a major limitation that has hindered the use of these materials in flexible electronics.
"The main finding of this study is the successful integration and adhesion of freestanding single-crystalline oxide membranes, thin crystalline sheets that are detached from their original growth surface, onto metallic titanium nitride (TiN)-coated flexible polymer substrates,” Professor Dae-Sung Park, one of the lead authors of the study, said in an email.
Complex oxides, materials composed of oxygen combined with metals such as manganese, titanium, or nickel, are widely regarded as some of the most versatile substances in modern materials science. Their properties range from magnetism to ferroelectricity, enabling them to generate magnetic fields or switch internal electric fields on and off.
They also display unusual electronic and catalytic behaviors, making them promising for use in electronics, energy systems, and advanced sensing technologies.
“Certain complex oxides offer many useful and diverse functionalities with high property tunability, some of which are not available in 2D materials,” explained Professor Nini Pryds, another lead author of the research.
Until recently, oxide films typically had to be grown on rigid crystalline substrates, restricting their application in flexible technologies. Advances in producing freestanding membranes have begun to change that, allowing oxides to be transferred onto flexible materials such as polymers or metals.
However, integrating these brittle membranes onto bendable surfaces remains difficult, as they are prone to cracking, wrinkling, or peeling away during handling or stretching.
Park noted that “the remaining challenges for the practical use of these membranes in various devices include enhancing their quality by minimizing defects such as microcracks, wrinkles, and surface contamination.”
In their experiments, the researchers transferred oxide membranes onto polymer sheets coated with different metals, including gold, platinum, and titanium nitride, to determine which surface provided the strongest adhesion and flexibility. They found that titanium nitride performed significantly better, allowing the membranes to adhere firmly and sustain uniform strain without detaching.
“This arises due to a strong interfacial interaction between oxide and TiN,” Park said, while Pryds emphasized that “selecting an appropriate metal surface for membrane integration is crucial for enhancing adhesion and ensuring structural integrity of the membranes.” The researchers say the method could open the door to flexible electronics, wearable medical sensors, foldable displays, and energy devices, while future work will focus on scaling up membrane production and building more complex layered structures.
