We present a methodology for building biologically inspired, soft microelectromechanical systems (MEMS) devices.

A mechanically active microgel platform for single cell mechanobiology is presented. Optically triggered nanoactuators generate isotropic compression in 3D microgels, leading to reversible and mechanosensitive calcium signaling in encapsulated MSCs.

Herein, a methodology for the directed self‐assembly of untethered microactuators and soft robotic microdevices from nanoscale building blocks is presented. The building block is a multifunctional stimuli‐responsive nanoactuator that consists of a magnetized gold nanorod encapsulated by a thermoresponsive hydrogel. The metallic core serves as a photonic nanoheater that transduces thermal energy from near‐infrared (NIR) light and a magnetic nanomotor that generates motion while driven by magnetic fields. Rapid control of temperature enables collective manipulation of nanoactuators through thermocapillary flows. In addition, catalytic activity of the nanorod instantiates a chemical reaction that covalently binds amine groups displayed on the surface of the surrounding soft gel capsule. A combination of optical and magnetic excitation realizes both reversible and permanent in situ assembly of microactuators within seconds that can perform both spatiotemporally controlled muscle‐like contraction (up to 30% strain) and motion. It is demonstrated that by linking nanoactuators with rationally designed compliant microstructures, more complex devices such as micromanipulators can be both fabricated and operated remotely. Colloidal assembly of microactuators ensures homogenous distribution of materials and functionality, thus preserving high performance provided by nanotechnology at multiple scales.

Classic microsurgical techniques, such as those used in the early 1900s by Mangold and Spemann, have been instrumental in advancing our understanding of embryonic development. However, these techniques are highly specialized, leading to issues of inter-operator variability. Here we introduce a user-friendly robotic microsurgery platform that allows precise mechanical manipulation of soft tissues in zebrafish embryos. Using our platform, we reproducibly targeted precise regions of tail explants, and quantified the response in real-time by following notochord and presomitic mesoderm (PSM) morphogenesis and segmentation clock dynamics during vertebrate anteroposterior axis elongation. We find an extension force generated through the posterior notochord that is strong enough to buckle the structure. Our data suggest that this force generates a unidirectional notochord extension towards the tailbud because PSM tissue around the posterior notochord does not let it slide anteriorly. These results complement existing biomechanical models of axis elongation, revealing a critical coupling between the posterior notochord, the tailbud, and the PSM, and show that somite patterning is robust against structural perturbations.