Design of soft implantable devices for tissue regeneration

Tissue repair has largely been approached with either tissue engineering or robotic-assisted grafting techniques, but in recent years, the strategy of combining mechanical stimulation to
promote cell proliferation and robotics has shown to be a promising alternative to traditional regeneration techniques. Nevertheless, this approach presents the challenge of triggering a
fibrotic response in the organ, where the mechanotherapy robot is placed, which may affect its physiological, anatomical and metabolic functions. The general hypothesis of this work is
that soft implantable devices that can provide controlled and localized mechanical stimulation are a physiologically, anatomically and metabolically compatible alternative to the current
strategies for tissue regeneration.

In this thesis, firstly we propose a soft pneumatic actuator, that can be helically arranged to provide multi-modal motions, in agreement with the anatomical needs of the target organ,
as well as load-bearing capabilities and a control scheme that regulates the stimulation provided to the tissue during therapy. Soft actuators are the building blocks of soft robots
that enable their motion and thus, secondly, derived from the inherent performance efficiency and reliability requirements for such a device as a medical tool, a systematic design analysis
focused on its building blocks’ geometry, configuration and response to variable loads is presented. As a result of this analysis conformed by numerical, statistical and experimental procedures we provide a set of design principles for the design of highly reliable soft pneumatic actuators. Finally, informed by those principles, we introduce the design, fabrication and characterization of two soft pneumatic actuators that supersede the extension and load-bearing capabilities of its previous version, and of many other state-of-art soft actuators,
providing the devices with an ability to treat a wider range of short-tissue related conditions.