Due to recent technological advancements, wearable computing has gained considerable attention. With it, users can interact with computers on the go, resulting in multiple new application scenarios that improve everyday life. The close proximity to the users body enables researchers to envision novel input and output techniques. While current research mainly focuses on novel sensing that assesses, for example, the physiological states of users, the output side also provides novel interaction opportunities. One promising wearable output technology is Electrical Muscle Stimulation (EMS). EMS is an actuating technology that utilizes the proximity to the body to actively take over control of the user’s body by actuating muscles. This enables control over the user’s actions (e.g., movements of the limbs) as well as perceptions of the environment (e.g., weight perception while lifting objects).

In this dissertation, we investigate how EMS can benefit humans in executing everyday life activities and how EMS systems should be designed in order to reach their full potential. We employ empirical research methods that are commonly used in human-computer interaction. In the beginning, we explain the interaction nature of EMS and the difference from other output technologies by extending fundamental interaction models.

Based on a structured literature review, we chart a taxonomy consisting of two main dimensions. The first dimension describes the purpose of the application. This is either to augment the human’s abilities in executing a certain task or to introduce the user to a new action or perception, which we refer to as induction. The second dimension classifies EMS applications from action to perception. The outcome of these two dimensions is four potential use case categories. Hence, we investigate scenarios from each category as well as mixed scenarios along the second dimension (i.e., action and perception). We explore these scenarios using six research probes.

Based on these research probes, we distill a set of recommendations and highlight the main challenges facing EMS-based systems. These findings provide a better understanding of the design requirements needed for systems using EMS. Our findings are centered around two main aspects: general research implications and implications linked to our proposed categories. Our work serves as a base for researchers and practitioners that are interested in exploring the opportunities of EMS as a wearable output technology.