A differentiable actuator extends potential configurations of modular robots

Mesenchymal stem cells (MSCs) can be differentiated into various cell lineages under the influence of mechano-niche. Inspired by this approach, this study presents a differentiable stem cell actuator unit (SAU) driven by a shape memory alloy, and a modular robotic framework. Similar to mechanically guided differentiation of MSCs, SAUs can be differentiated into a series of differentiated actuator units (DAUs) under external preload. This process has been modeled, simulated, and experimentally validated, with testing conducted on three distinct types and 14 specifications of DAUs. DAUs weighing as light as 1.96g exhibited outputs reaching up to 10.6 N and 46.32 Nmm. Our team has developed seven application prototypes based on this bio-inspired framework including mobile robots, manipulators and end effectors. This work pioneers the integration of differentiable concepts and principles into the design of modular robots, enabling a wider range of potential configurations and capabilities.