The collection of passive data using smartphone sensors is gaining ground in social science research. In general, it is aimed at obtaining location and motion data to detect participants` activities in a study setting. Therefore, the Centre for Social Informatics at the Faculty of Social Sciences has been developing a mobile application "1KA Panel" for an integrated collection of survey and sensor data on mobile devices that users will be able to install on their smartphones in order to participate in various social research studies. This thesis presents the development and design of a middle-fidelity user interface prototype for an Android mobile application. We were interested in what kind of recommendations and guidelines are the most important in the design of the user interface prototype, how to approach its development, and what aspects should be considered in the design process to include all required functionalities into the prototype. We have found that guidelines at multiple levels are important during the prototype design as we must follow the general principles for the development of the user interface, a specific approach to the design of mobile applications and the Android official guidelines. In the prototype development process, we need to consider four key steps: plan, specification, design and results. The design of our prototype has shown that, despite a relatively simple information architecture of the mobile application, twenty-five screens with appropriately embedded components of user interface will be required for its functional operation.