# Design of Personalized Devices--The Tradeoff between Individual Value and Personalization Workload
## 2 Materials and Methods
### Example Product Flow Diverter  
For the purpose of clarifying each step of the new method and demonstrating how it can be applied, a flow diverter was used as an example product in the next section. A flow diverter is a braided stent that is implanted into the diseased vessel in order to treat intracranial aneurysms. The implant reconstructs the blood vessel and alters the blood flow so that the aneurysm can regress [35; 36]. Flow diverters are produced using a braiding process. First, the mesh is created by weaving together thin, nitinol wires. It is then subjected to heat treatment, during which it is shaped so that it returns to its embossed form at body temperature after having been folded for implantation [37]. The flow diverter is implanted using a catheter treatment for minimal invasiveness. For this purpose, the mesh is advanced through the femoral artery, the aorta, and the carotid by using a system of access and catheters until it reaches the diseased vessel in the head. The position of the implant in the vessel is of crucial importance and has a significant impact on the healing of the aneurysm. One possible complication of the implantation process is an incorrect wall apposition of the flow diverter. The implant can migrate if the wall position is insufficient [38] and, in the worst-case scenario, may even prolapse into the aneurysm sac [39]. Sufficient wall apposition is crucial in order to prevent thrombus formation following deployment of the flow diverter, which can lead to thromboembolic complications [40]. Moreover, sufficient wall apposition along the treated vessel is significantly associated with complete aneurysm occlusion [41]. The position of the distal and proximal end of the implant is also very important. If the distal anchorage zone is too short, this can lead to migration of the implant after, or even during, treatment. If the proximal end is positioned incorrectly, for example, in a pronounced vascular curve, this can result in a fishmouth, which is the term used to describe when the proximal end of the implant does not open all the way.  
To prevent these handling complications from occurring during implantation, it is essential to select the best-fitting implant variant from the product portfolio to suit the patient's individual anatomy. However, repeated mistakes in implant size selection indicate that medical staff do not receive sufficient assistance when selecting the best implant variant, and may even be a sign that the product portfolio is too small. In order to prevent the former of these issues, _Acandis GmbH_ introduced the _Ankyras Sizing Tool_ (Galgo Medical Inc., Barcelona, Spain), which allows patient-specific planning of the position of an implant variant in an individual patient blood vessel [42]. In order to improve the alignment of the  
Figure 3: (**a**) Structure of a TEV representing a product family with predefined product variants, and (**b**) structures of a 3-level and 4-level VAM.  
product portfolio, it is proposed that the mesh could be adapted to suit patient-specific needs and the product could be personalized. The method presented in this paper will be used to investigate whether product individualization is effective and can be implemented in a way that is manageable in terms of complexity.  
In order to apply the newly developed method to the case of the flow diverter, it is advisable to work in an interdisciplinary team with the involvement of the user [14]. For this reason, an interdisciplinary team of researchers with experts from different fields has been put together to analyze and evaluate the product personalization for the flow diverter:  
* Physicians--anatomy experts for the evaluation of individualized designs
* Development engineers--flow diverter product experts for the personalization of the design
* Method consultants--experts in the development and application of design methods