Currently, people spend many more hours on smartphones, and the potential impact of phone radiation is receiving more attention. Reducing the impact of a phone’s magnetic field on human health is vital. Although many studies advise changing phone use habits, such as reducing call times to impede phone radiation, there are no specific products found in the literature to prevent or reduce phone radiation. Therefore, this study used TRIZ theory as a research method to design prototypes in order to reduce the potential impacts of magnetic fields generated by smartphones on the human body. The results show that the distance between the human body and the phone is negatively related to phone radiation; the longer the distance is, the less phone radiation there is. Three prototypes have been designed through this research in order to reduce a phone’s radiation. The first testing condition simulates a phone conversation in which the prototypes are installed on the phone while having a WhatsApp conversation. The second testing condition simulates phone standby mode in which the prototypes are installed on a phone while the phone’s Wi-Fi, Bluetooth, data, GPS, and hotpot are on. A magnetic field tester was used to measure the magnetic fields every 5 s, and each measurement set lasted for 3 min. Five sets of measurements were completed at the end, and the average result shows that the use of prototypes under these two conditions can reduce 100% and 90% of the magnetic field generated by a smartphone during a phone conversation and the phone’s standby mode, respectively.