  With the ever-growing interest in the area of mobile information retrieval
and the ongoing fast development of mobile devices and, as a consequence,
mobile apps, an active research area lies in studying users' behavior and
search queries users submit on mobile devices. However, many researchers
require to develop an app that collects useful information from users while
they search on their phones or participate in a user study. In this paper, we
aim to address this need by providing a comprehensive Android app, called
Omicron, which can be used to collect mobile query logs and perform user
studies on mobile devices. Omicron, at its current version, can collect users'
mobile queries, relevant documents, sensor data as well as user activity and
interaction data in various study settings. Furthermore, we designed Omicron in
such a way that it is conveniently extendable to conduct more specific studies
and collect other types of sensor data. Finally, we provide a tool to monitor
the participants and their data both during and after the collection process.
