# A Novel Soft Robotic Exoskeleton System for Hand Rehabilitation and Assistance Purposes
## 3 Results and Discussion
### Experimental Procedure and Validation  
After the development and assembly of the SEG device, the next step is a basic series of tests in order to verify the functionality and durability of the produced product. The first test concerns the ability of the SEG to produce a sufficient palmar grasping force to accomplish the desired task. According to existing literature [6; 35], the ADLs require a palmar grasping force between 10 N to 15 N deriving from the weight of objects of daily living (ODLs), which reach up to 1.5 kg. Therefore, the developed SEG was designed to generate a distal tip force of 7.3 N and 14.5 N at each finger for the operating air pressures of 200 kPa and 250 kPa, respectively. Thus, for a median coefficient of static friction of OBLs at 0.26 [35], which is a conservative estimation, the aforementioned distal tip forces are transformed into palmar grasping forces of almost 1 kg and 1.9 kg for operating air pressures of 200 kPa and 250 kPa, correspondingly. The durability of the SEG device was measured in terms of consecutive full flexion motion cycles (i.e., from 0\({}^{\circ}\) to 180\({}^{\circ}\)). The layout of the experiment is depicted in the left image of Figure 6c. The frequency of the angular flexion motion was 30 cycles per minute which is a relatively high speed for APLs. Hence, with this configuration, the SEG showed a remarkable performance, as it had undergone more than 40,000 flexion cycles before the failure of one of the actuators due to the fatigue of the silicone rubber compound. It is worth mentioning that in the case of an \begin{table}
\begin{tabular}{c c} \hline \hline
**Description** & **Technical Characteristics** \\ \hline Power Supply & 110–220 V (50–60 Hz) \\ Connectivity & WiFi, USB type B \\ Air Supply & 300–1000 kPa \\ Operating Air Pressure & 200–250 kPa \\ Circuit Voltage & 3.3 V DC \\ Control Glove Power Supply & 5 V DC \\ Control Glove Battery & Li-Po 3.7 V—550 mAh \\ Operating Actuators & 5 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Technical characteristics of the developed SEG device. Figure 8: (**a**) Final configuration of overall SEG device along with its main components; (**b**) Illustrative flowchart of the SEG device function. actuator's failure, the actuator could be easily replaced. Furthermore, the motion's speed of the SEG is constant during the device operation and could be changed by the output pressure of the flow regulator. In the context of this study, the nominal motion speed has a value of 90\({}^{\circ}\)/s for an output pressure of 250 kPa. Having proven the functionality and durability of the SEG device, the next process was the proper validation of the device in order to become a commercial product and be ready for clinical trials. Therefore, the designed SEG device underwent a series of tests in order to prove its compliance with health, safety, and environmental protection requirements deriving from the European Union (EU) Directives and to obtain the CE marking. In detail, the tests examined the device for electromagnetic compatibility (EMC test), electrical safety (low voltage directive--LVD test), Restriction of Hazardous Substances (RoHS evaluation), etc. All these tests were performed by an independent contractor certificated by the EU, namely the company LABOR S.A. (European Notified Body 2537). The presented configuration of the developed SEG device successfully passed all the required tests and received the CE mark. Hence, the SEG device is now a commercial product that complies with the EU Directives. However, to expand the application of the device in the health sector, it was essential to evaluate its performance through clinical trials.