Additive Manufacturing of Soft, Functional Structures for Next-Generation Soft Robotics

Abstract

Soft electroactive structures like dielectric elastomers (DEs) show great potential for many applications in soft robotics or wearable devices. However, high-quality fabrication of soft devices, and particularly DEAs, remains a great challenge both in terms of materials and manufacturing methods. Many different fabrication techniques have been developed but these are often very time- and labour intensive or require very expensive, specialised equipment that is not accessible to every researcher or company interested in this technology. In this thesis, novel, low-cost materials and manufacturing methods for soft, functional structures are explored.
A method to fabricate patterned, stretchable electrodes for DE actuators (DEAs) from laser-scribed graphene oxide (LSGO) is proposed. The method uses a simple drop casting technique and a low-cost laser engraver to produce arbitrary electrode patterns with 100 μm resolution. LSGO has previously been used in various electronic devices but never to produce stretchable electrodes for soft actuators. LSGO DEAs are shown to have similar performance compared to DEAs made by more conventional methods.
To move towards fully automated fabrication of soft 3D structures, a novel 3D printing technique is proposed. This technique, called Laser-Assisted Multi-material Direct-write Assembly (LAMDA), combines simple direct ink writing and laser scribing into one integrated process. Laser scribing is used to alter the chemical composition and properties of the deposited materials. This allows fabrication of multi-material structures without the need for multi-material deposition, making the required 3D printer hardware very simple and affordable (~£1000). The LAMDA process is capable of producing electrically conductive layers and traces throughout the printed part. It can also incorporate layer separations for inflatable cavities. This technique could pave the way for easier fabrication and prototyping of DE devices and might enable completely new shapes and functionality that would not be accessible by conventional manufacturing methods.

Date of Award	1 Oct 2019
Original language	English
Awarding Institution	The University of Bristol
Supervisor	Charl F J Faul (Supervisor), Jonathan M Rossiter (Supervisor) & Arthur G Richards (Supervisor)