The Soft Robotics Toolkit announced the winners of their 2017 competition last month, giving prizes for Contributions in Soft Robotics Research, the educational Design Competition Awards, and Honorable Mentions.
The Organic Robotics Lab at Cornell University won the Prize for Contributions in Soft Robotics Research, with their Foam-based Soft Actuator project. Ben MacMurray, Alfredo Argiolas, and Robert Shepherd were recognized for their actuators that use open-celled elastomer foam as the structure and a nonporous elastomer as the seal.
The actuators are generally made from an open-celled elastomer foam, a strain limiting layer, and a sealing layer. The open cells allow fluid to easily travel throughout the structure, and Cornell found a lost salt process and castable polyurethane foams worked the best in their process.
Plastic mesh, woven fibers or elastomers with a higher stiffness than the actuators are used as the limiting layer. The strain-limiting layer directs the motion of the actuator, and a sealing layer makes the actuator airtight. Two different lost salt processes are used, ammonium bicarbonate and table salt. Ammonium bicarbonate is a faster process but the table salt process uses nonhazardous chemicals. Ecoflex 00-10 is the silicone used as the actuator base with the salt mixed in according to desired porosity. The mix of silicone and salt can be formed into the desired shape or poured into mold and then when cured the shape is placed into water and the salt dissolves. The entire Foam-Based Soft Actuators page is fascinating, with sections devoted to Design, Fabrication, Modeling, Testing, Case Study and a download of the lab's Formulation Tool spreadsheet. It's great to see the hardcore science and chemistry that goes into the foams and forms, and then the absolute craftsmanship required to obtain the desired shapes and functions.
The Soft Robotics Toolkit continues to be my favorite place to look for news and resources revolving around soft robotics. After starting as a collaboration between Harvard's Biodesign Lab and Trinity College Dublin's Soft Robotics Group, the site has become a showcase for several projects from around the world and an excellent Educator Resource section with projects to illustrate the components of soft robotics.