Soft robotics in wearable and implantable medical applications: Translational challenges and future outlooks

This work explores the recent research conducted towards the development of novel classes of devices in wearable and implantable medical applications allowed by the introduction of the soft robotics approach. In the medical field, the need for materials with mechanical properties similar to biological tissues is one of the first considerations that arises to improve comfort and safety in the physical interaction with the human body. Thus, soft robotic devices are expected to be able of accomplishing tasks no traditional rigid systems can do. In this paper, we describe future perspectives and possible routes to address scientific and clinical issues still hampering the accomplishment of ideal solutions in clinical practice

A Self-sensing Inverse Pneumatic Artificial Muscle

In recent years, the inverse pneumatic artificial muscles attained great attention in soft robotics, especially for the wider motion range compared to traditional positive pneumatic actuators. Besides self-sensing is a recognized highly desirable property for soft actuators to enable proprioception and to facilitate the soft robots control, a self-sensing strategy for a soft inverse pneumatic muscle was still missing. In this paper, we present the first self-sensing inverse pneumatic artificial muscle in which the reinforcing but compliant element that guides the actuator motion during actuation has not only a mechanical function but, being also electrically conductive, it endows the actuator with self-sensing. Here, the actuator design and manufacturing are described, together with an electro- mechanical characterization. In addition, we demonstrate its self-sensing capability in a dynamic setting, by predicting the actuator strain from its electric resistance variation, through a calibration model

Variable Stiffness Linear Actuator Based on Differential Drive Fiber Jamming

Variable stiffness technologies have been widely adopted in soft robotics, also combining them with different actuation technologies and demonstrating the potential to increase the range of possible applications of soft systems, such as soft continuum manipulators. However, in most cases, the variable stiffness capabilities of these soft system are far from satisfying the application requirements. With the aim to explore new possibilities to fill this gap, in this work, we present a novel variable stiffness linear actuator (VSLA) based on the combination of composite fiber jamming and the inverse pneumatic artificial muscles working principle. The differential pressure driving approach adopted to control the VSLA decouples the actuator deformation from the variable stiffness capabilities, and this makes the VSLA a suitable candidate for the realization of new kind of continuous arms. Moreover, the VSLA novel architecture introduced in this article was analytically modeled considering the interaction among constituent elements and performances in different loading conditions have been computed. The results obtained from the experimental tests validated the model goodness in terms of assumptions made and showed remarkable variable stiffness capabilities, with a maximum jamming ratio that reaches 21.3

Soft robotics for physical simulators, artificial organs and implantable assistive devices

In recent years, soft robotics technologies enabled the development of a new generation of biomedical devices. The combination of elastomeric materials with tunable properties and muscle-like motions paved the way toward more realistic phantoms and innovative soft active implants as artificial organs or assistive mechanisms. This review collects the most relevant studies in the field, giving some insights about their distribution in the past ten years, and their level of development, and opening a discussion about the most commonly employed materials and actuating technologies. The reported results show some promising trends, highlighting that the soft robotics approach can help replicate specific material characteristics, in the case of static or passive organs, but also reproduce peculiar natural motion patterns for the realization of dynamic phantoms or implants. At the same time, some important challenges still need to be addressed. However, by joining forces with other research fields and disciplines, it will be possible to get one step closer to the development of complex, active, self-sensing and deformable structures able to replicate as closely as possible the typical properties and functionalities of our natural body organs

Modelling and characterization of a Soft Inverse Pneumatic Artificial Muscle

Pneumatic artificial muscles are some of the most famous linear actuators in bio-inspired robotics. In this study, improved manufacturing and modelling of a Soft Inverse Pneumatic Artificial Muscle (SIPAM) are presented. The proposed actuator is able to contract of nearly 70% while simultaneously applying a pulling force. The inverse actuation scheme consists in a muscle elongation upon pressurisation, followed by a passive contractile phase. Experimental tests were conducted to validate the proposed model. The results showed that our model is able to capture the SIPAM non-linear behaviours, and demonstrate that this artificial muscle can work at frequencies that are comparable to the ones of the natural muscle contraction