This is a 5-month master graduation project in collaboration with Praxa Sense to design the next generation Atrial Fibrillation diagnosis device. A long-term (more than one month) continuous, off-hospital diagnosis device is designed with the focus on user experience and diagnosis accuracy. There are several phases in this project including research and analysis, defining the scope, synthesis and design, and evaluation. Desktop research and interviews were carried out during the research phase, which helped to define the scope of this wicked problem. Then synthesis and design cover the ideation, concretization and detailed design of the final product, in which various design methods were applied. Evaluation includes different user test of the product.The result is the most compact and comfortable Atrial Fibrillation diagnosis device in the market with medical grade diagnosis.