Kaj studied Biomedical Engineering at the University of Twente, Enschede. In 2011 he did an internship at the Gadjah Mada University, Yogyakarta (Indonesia), where he adapted the design of a tibia bone plate for the Indonesian anthropology using x-ray data. His master’s thesis focused on 3D target localization within curved objects using ultrasound, within the group of Biomechanical Engineering in collaboration with the Robotics and Mechatronics group. As of October 2013, he works as a PhD-student in the ERC-BioMechTools project of Nico Verdonschot within the Orthopaedics Research Laboratory. This project is in collaboration with the Medical Ultrasound Imaging Center of Chris de Korte, to develop ultrasound diagnostic tools for the deformation of soft tissues within the lower extremities.