## 2 Materials and Methods  
### Analysis of Requirements  
A preliminary review of the existing technical literature on pediatric hand exoskeleton design was performed to support the identification of key design requirements. The analysis included both research prototypes and commercial devices with the aim of identifying common functional objectives and key design strategies. Several aspects were considered: target medical conditions, development maturity, intended age group, actuation mechanisms, overall device architecture, assisted Degrees of Freedom (ADoFs), strategies for user intention detection, and fingers supported. A Boolean query that deliberately restricted the search results to only those technical works addressing the design problem for pediatric application was defined: (\"exoskeleton\" OR \"robotic exoskeleton\" OR \"powered exoskeleton\" OR \"wearable exoskeleton\" OR \"robotic device\") AND (\"hand\" OR \"wrist\" OR \"fingers\") AND (\"pediatric\" OR \"children\" OR \"infants\" OR \"adolescents\"). A constraint was applied to restrict the occurrence of these terms to the title or abstract. The search yielded 16 studies. Following a screening process based on relevance, target population and application area, eight studies were retained. Table 1 provides an overview of the main characteristics, including the mechanical and functional attributes, thereby facilitating a comprehensive evaluation of the identified exoskeletons. In addition, it offers an assessment of the current stage of development. Exoskeletons were divided into rehabilitative [11; 13; 14; 20] and assistive [5; 12; 16; 21] types, which are equally represented. The former aim to restore motor functions temporarily compromised by injury or disease, whereas the latter are primarily designed to support users in the home environment, particularly during ADLs [3]. Furthermore, a consistent distribution in the types of exoskeletons is observed across categories. The proportion of soft exoskeleton [14; 20; 21] and rigid exoskeleton [11; 13; 16] papers is balanced. Although rigid exoskeletons provide high-precision control and efficient force transmission, their bulk and the difficulty in accommodating joint misalignments have limited their applicability, particularly for pediatric users [23]. In contrast, soft exoskeletons offer advantages such as reduced weight and lower bulk, yet their compliant structures introduce significant control challenges. As a result, soft-rigid architectures [5; 12], which combine rigid and soft components, have emerged as a promising alternative [24]. These systems offer a favorable trade-off, enabling lightweight designs while ensuring sufficient structural rigidity [25]. From a mechanical perspective, two critical parameters include the Degree of Actuation (DoA) and the type of transmission mechanism implemented. Fingers are usually numbered from 1 (thumb) to 5 (little finger). The proportion of devices providing assistance to fingers 1 through 5 [5; 15] is comparable to that of devices assisting only fingers 1 to 3 [20; 21], which is a pattern commonly used by children. Transmission can be grouped into five main categories that take into consideration the implemented type of energy transduction [23]: bladder (fluidic transmission and pneumatic transduction), cable on glove (flexible transmission and electric transduction), constrained sliding (flexible transmission and thermal transduction), coupled DOF (linkage transmission and electric transduction), and independent DOF (linkage transmission and electric transduction). The results of our analysis highlight evident heterogeneity in the type of transmissions adopted across existing systems. Notably, the percentage of bladder systems [14; 15] and independent DOF systems [11] appears to be comparable. Both these approaches present notable limitations. Bladder-based systems, which rely on pneumatic transducers, tend to suffer from low portability due to the bulk of ancillary components such as air compressors [3; 23].