The widespread distribution of smart mobile devices offers promising perspectives for the timely collection of huge amounts of data. When realizing sophisticated mobile data collection applications, numerous technical issues arise. For example, as many real-world projects require the support of different mobile operating systems, platform-specific peculiarities must be properly handled. Existing approaches often rely on specifically tailored mobile applications. As a drawback, changes to the data collection procedure result in costly code adaptations. To remedy this drawback, a model-driven approach is proposed, enabling end-users (i.e.,domain experts) to create mobile data collection applications themselves. This model relies on complex questionnaires called instruments. An instrument not only contains all information about the data to be collected, but additionally comprises information on how it shall be processed on different mobile operating systems. For this purpose, we developed an advanced mobile (kernel) service being capable of processing sophisticated instruments on various platforms. This paper discusses fundamental kernel requirements and introduces the developed architecture. Altogether, the mobile service allows for the effective use of smart mobile devices in data collection application scenarios (e.g., clinical trials).