As the world moves towards cleaner energy sources, hydrogen is gaining popularity. However, safety concerns around its production, use, and transportation have been raised due to its highly flammable nature. To address these concerns, researchers at the Institute of Science Tokyo, led by Prof. Yutaka Majima, have developed an innovative sensor for ultra-low concentration hydrogen detection. The sensor, made with nano-patterned CuO nanowires, operates by detecting changes in electrical resistance when exposed to hydrogen gas. By introducing a pre-annealing step and optimizing the nanowire structure, the sensor can detect hydrogen concentrations as low as 5 parts per billion (ppb) and responds rapidly in just seven seconds. The sensor's enhanced performance, including resistance to humidity and faster response times, makes it a significant advancement in hydrogen safety technology. Prof. Majima and his team plan to utilize this sensor technology to develop sensors for other hazardous gases, contributing to a safer adoption of hydrogen technologies and the transition to a hydrogen-based economy.