Step 2. Prototype development
We began the prototype development after completing the analysis of the results from the online survey and the 22 in-depth interviews. Regarding the app functions, we outlined desired functions which included pushed notifications, library content, and the mechanism for a triple–blinded controlled trial. We also created visual mock-ups with interface design reviewed by team members and revised. We selected target behaviors, identified key determinants of the behavior, and then mapped the push notifications to develop library content.