O2U is a portable oxygen concentrator carried on the human body with a small volume and lightweight. With a non-medical appearance and reduced size, it enhances mobility and also encourages users to go outdoors while using it, without getting any unwanted attention. A strap wrap, arm wrap and shoulder strap are supplied for multiple purposes, catering for users' needs in different outdoor situations. Carrying an extra bag for a bulky concentrator is not necessary anymore. The simple and intuitive interface means users can understand how to use it easily and also allows others to configure it quickly in emergencies. For the nasal cannula design, the tubes of the nasal part can be detached and changed according to users' preference. Users can choose their suitable cannula and also reduce the waste of plastic. This product changes people's perception of medical products and gives them more confidence using it in public, due to it's trendy appearance. The application design is not only for recording user habits and statistics for more precise diagnosis but also provides a platform for them to interact. It can improve the patient's social conditions and gain mental support by connecting with others.