# A Novel Soft Robotic Exoskeleton System for Hand Rehabilitation and Assistance Purposes
## 1 Introduction  
Nowadays, rapid development in sectors of advanced robotic systems, automation, and smart manufacturing is observed due to the 4 th industrial revolution [1, 2]. Heavy industries have already embedded these systems in their production in order to optimize their workflows [3]. Robotic systems and automation are currently employed in a wide spectrum of applications, either for industrial or commercial use. On top of this, additive manufacturing technologies allow the customization of the produced products depending on the customer's needs [4, 5]. Hence, the combination of these systems offers a great opportunity to utilize them in customized applications, especially in the health sector, as the needs differ from patient to patient. More specifically, in the last decade, a series of robotic systems and automation were designed and developed to reinforce the available tools in the health sector, namely robotic exoskeletons [6], drug distribution [7], health monitoring devices [8], etc. In addition, the advances in additive manufacturing technologies and feedstock materials have enabled the customized fabrication of the aforementioned products with patient-adapted designs [9] and human-friendly materials [10]. Thus, thecurrent research presents the development and production of a novel soft robotic exoskeleton system for hand rehabilitation and assistance purposes constructed with the aid of additive manufacturing methods. Prior to providing any further details, it is essential to introduce the hand exoskeleton's devices, classifying them and listing their advantages and disadvantages. Hand exoskeletons are divided into three categories soft exoskeletons, rigid exoskeletons, and soft-rigid exoskeletons [11]. Soft exoskeletons are safer and provide natural movement and comfortability; however, it is difficult to produce sufficient force [12]. On the other hand, rigid exoskeletons produce enough force with abnormal movement and bulk designs [13]. Finally, a recent study has proposed the development of a hybrid soft-rigid hand exoskeleton to increase the efficiency of the device. Nevertheless, some disadvantages still occur, such as the difficult application on the human hand and the lack of comfortability [14]. Many people around the world are facing mobility difficulties and neurological disorders in different parts of their bodies, which require either special care to rehabilitate or intense assistance in order to obtain partial or full functionality of their affected limb for the accomplishment of activities of daily living (ADLs) [15]. One of the most common and crucial mobility disorders concerns the partial or full disability of hand and finger movement resulting from a stroke, neurological condition, or injury [16]. More than 50 million elderly people worldwide face these kinds of motion difficulties, increasing even more if younger people with injuries or neurological conditions are taken into account [15]. Thus, there is a necessity to develop tools and devices that could facilitate the rehabilitation process or even restore to some extent or completely hand and finger function with the assistance of exoskeletons. It is essential to clarify that besides the rehabilitation use, exoskeletons could also be used in ADLs in order to assist and perform the desired range of movements by patients. Towards this direction, in the last decade, several studies have been published analyzing the kinematics of the human hand and developing advanced soft exoskeleton gloves (SEGs) [6; 17; 18]. One of the first and most comprehensive research on SEG's development has been performed by [PERSON] et al. [6]. In this work, the kinematics of a human hand was observed and analyzed via electromagnetic (EM) tracking sensors. Then, a soft pneumatic actuator from elastomeric material reinforced with woven material was designed and fabricated. Afterward, five of these actuators were assembled on a fingerless glove.