Mechanical oscillation in living active matter

Living materials are promising for engineering programmable autonomous matter that hold potentials for a range of applications such as cargo delivery, soft robotics, and self-driven biotherapeutics.  The key to realizing these potential applications is to understand and command the emergent mechanics in living matter.  Here we report an emergent mechanical behavior in bacterial living matter that enables delivering and sensing of large-scale mechanical forces in a collective manner.  We discovered that the coupling between coordinated bacterial motility in collectives and the elastic mechanical environment led to global and regular mechanical oscillation. Our work establishes a novel mechanism of large-scale force generation in the bacterial world, informing the design of autonomous mechanical functionalities in bacteria-based living materials and opening new avenues for mechanobiology during biofilm formation and bacteria-host interactions.