Carolin S. Klein ^1,2 Karsten Hollmann ^1,2* Jan Kühnhausen ^1,2 Annika K. Alt ^1,2 Anja Pascher ^1,2 Lennart Seizer ^1,2 Jonas Primbs ³ Winfried Ilg ⁴ Annika Thierfelder ⁴ Björn Severitt ⁵ Helene Passon ⁶ Ursula Wörz ⁷ Heinrich Lautenbacher ⁷ Wolfgang A. Bethge ⁸ Johanna Löchner ^1,2 Martin Holderried ⁹ Walter Swoboda ¹⁰ Enkelejda Kasneci ¹¹ Martin A. Giese ⁴ Christian Ernst ⁶ Gottfried M. Barth ^1,2 Annette Conzelmann ^1,12,2 Michael Menth ³ Caterina Gawrilow ^13,2 Tobias J. Renner ^1,2

• ¹ Department of Child and Adolescent Psychiatry, Psychosomatics and Psychotherapy, University Hospital Tübingen, Tübingen, Germany, Tübingen, Baden-Württemberg, Germany
• ² DZPG (German Center for Mental Health), Tübingen, Germany
• ³ Department of Computer Science, Communication Networks, University of Tübingen, Germany, Tübingen, Germany
• ⁴ Hertie Institute for Clinical Brain Research, Theoretical Sensorimotor Section, University of Tübingen, Germany, Tübingen, Germany
• ⁵ ZEISS Vision Science Lab, University of Tübingen, Germany, Tübingen, Germany
• ⁶ Economics and Management of Social Services, Institute for Health Care and Public Management, University of Hohenheim, Germany, Hohenheim, Germany
• ⁷ Information Technology Division, University Hospital Tübingen, Tübingen, Germany, Tübingen, Germany
• ⁸ Center for Clinical Studies Tübingen, University Hospital Tübingen, Tübingen, Germany, Tübingen, Germany
• ⁹ Department of Medical Development, Process and Quality Management, University Hospital Tübingen, Tübingen, Germany, Tübingen, Germany
• ¹⁰ Faculty of Health Management, University of Applied Sciences Neu-Ulm, Germany, Neu-Ulm, Germany
• ¹¹ Human-Centered Technologies for Learning, Department of Educational Sciences, TUM School of Social Sciences and Technology München, Germany, München, Germany
• ¹² PFH – Private University of Applied Sciences, Department of Psychology (Clinical Psychology II), Göttingen, Germany, Göttingen, Germany
• ¹³ Department of Psychology, Faculty of Mathematics and Natural Sciences, University of Tübingen, Tübingen, Germany

The present study investigates the feasibility and usability of a sensor-based eHealth treatment in psychotherapy for pediatric obsessive-compulsive disorder (OCD), and explores the promises and pitfalls of this novel approach. With eHealth interventions, therapy can be delivered in a patient's home environment, leading to a more ecologically valid symptom assessment and access to experts even in rural areas. Furthermore, sensors can help indicate a patient's emotional and physical state during treatment. Finally, using sensors during exposure with response prevention (E/RP) can help individualize therapy and prevent avoidance behavior. In this study, we developed and subsequently evaluated a multimodal sensor-based eHealth intervention during 14 video sessions of cognitivebehavioral therapy (CBT) in 20 patients with OCD aged 12-18. During E/RP, we recorded eye movements and gaze direction via eye trackers, and an ECG chest strap captured heart rate (HR) to identify stress responses. Additionally, motion sensors detected approach and avoidance behavior.The results indicate a promising application of sensor-supported therapy for pediatric OCD, such that the technology was well-accepted by the participants, and the therapeutic relationship was successfully established in the context of internet-based treatment. Patients, their parents, and the therapists all showed high levels of satisfaction with this form of therapy and rated the wearable approach in the home environment as helpful, with fewer OCD symptoms perceived at the end of the treatment. The goal of this study was to gain a better understanding of the psychological and physiological processes that occur in pediatric patients during exposure-based online treatment. In addition, 10 key considerations in preparing and conducting sensor-supported CBT for children and adolescents with OCD are explored at the end of the article. This approach has the potential to overcome limitations in eHealth interventions by allowing the real-time transmission of objective data to therapists, once challenges regarding technical support and hardware and software usability are addressed.Clinical trial registration: [www.ClinicalTrials.gov], identifier [NCT05291611].