Liquid to Gel Transitions in 3D Active Networks

We are investigating the origin of self-amplifying deformations in 3D active networks composed of cytoskeletal filaments (microtubules), crosslinkers and molecular motors. The motors hydrolyze ATP and convert chemical energy into mechanical work as they slide adjacent microtubules. This input of energy drives the cytoskeletal network away from thermodynamic equilibrium. We shear-aligned this suspension in thin microfluidic channels and investigate how the kinematics of the instability can reveal the underlying rheology of the network. In particular, we investigate the role of microtubule length on the rheology of the network and show that increasing the length of the polymer leads to a transition from an active liquid to an active solid.