Tutorial SF13—Soft Actuators and Robotic Systems for Living Machines

Research in stimuli-sensitive soft actuators has gained considerable emphasis in recent years due to their increasing demand for applications where nature-inspired robotic movements are required. These actuators are rapidly emerging at the frontier of technological innovations due to their wide array of applications in humanoid robots, artificial muscles, energy harvesting materials or in-production technologies (e.g., as micro grippers). The tutorial will cover the fundamentals of bio-inspired soft actuators and their recent progress and applications, especially energy harvesters. Stimuli-sensitive materials such as shape-memory polymers and liquid crystalline elastomers will be highlighted and introduced. Furthermore, the tutorial introduces polymer processing, micro/nano-technologies and in-situ characterization (e.g. atomic force microscopy) of soft actuators.

Soft Actuators
Muhammad Farhan, Helmholtz-Zentrum Hereon

An introduction in the field of soft actuators and soft robotics followed by various application areas of soft actuators will be covered here. A detailed survey on materials in use and fabrication methodologies for soft actuators will be given. Furthermore, a range of stimuli for actuation, deformation capabilities, motion complexities and varied multifunctionality in the soft actuators will be discussed.

• Bio-inspired structures and materials
  The most recent research on polymer-based bio-inspired structures and materials will be presented. The focus will be hybrid and multi-material systems inspired by plants, for which the arrangement of different materials and their structure-function relations will be discussed. Finally, plant-inspired movements in such artificial systems and their applications will be covered in this topic.
• Stimuli-sensitive material for actuators, e.g., shape-memory polymers, liquid crystalline elastomers
  Fundamentals of stimuli-sensitive materials and how the shape-memory effect or actuation can be utilized to fabricate bioinspired actuators will be covered in this topic. Network architectures of shape-memory polymers and liquid crystalline elastomers, understanding of various types of shape-memory effects and actuation, parameters or factors influencing the performance of actuators and their characterization methods will be discussed.
• Polymer processing technologies
  The topic will cover the introduction into various conventional polymer processing such as extrusion, injection or compression molding. An introduction to 3D printing will also be part of this topic and later, the use of various technologies in the fabrication of actuators will be elaborated. The usage and various product ranges from different processing techniques will also be discussed.

In-Situ Characterization by Atomic Force Microscopy
Yue Liu, Helmholtz-Zentrum Hereon

Atomic force microscopy, as a platform for implementing and characterizing functional materials on the micro/nano-scale, was developed and will be introduced here from the basics, such as scanning modes, influence of cantilever tip, force measurements and other advanced applications. Particularly, in-situ characterization of different morphologies, monitoring shape reconfiguration of structured surfaces, particles and fibers during active movement will be discussed.

• Micro/nano-technologies of soft actuators
  The design/fabrication, functionalization, actuation and localization of soft actuators on micro/nanoscale will be introduced. The principles of different actuation methods and their limitations will be analyzed. Examples of biomedical applications, micro-/nanorobots or sensors will be presented. The key challenges and future development directions will be discussed.

Energy Conversion in Living Plants
Fabian Meder, Italian Institute of Technology

We will describe how the materials occurring in leaves could convert mechanical energy, such as from wind and raindrops, into electricity using solid-solid or liquid-solid contact electrification of the leaf cuticle. The resulting electrical signals differ from active electrophysiological signals like action potentials that can be analyzed with soft organic electrodes on the plant surfaces.  We will show how living plants, based on the above-mentioned phenomena, can be used for wind energy harvesting and sensing exploiting leaves fluttering in the wind. We will describe how the electricity produced by a few leaves can be used to power commercial low-consumption electronics like LEDs and sensors.