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Keywords:

  • microfluidics;
  • polymers;
  • shape-memory materials

Abstract

Materials with embedded vascular networks afford rapid and enhanced control over bulk material properties including thermoregulation and distribution of active compounds such as healing agents or stimuli. Vascularized materials have a wide range of potential applications in self-healing systems and tissue engineering constructs. Here, the application of vascularized materials for accelerated phase transitions in stimuli-responsive microfluidic networks is reported. Poly(ester amide) elastomers are hygroscopic and exhibit thermo-mechanical properties (Tg ≈ 37 °C) that enable heating or hydration to be used as stimuli to induce glassy-rubbery transitions. Hydration-dependent elasticity serves as the basis for stimuli-responsive shape-memory microfluidic networks. Recovery kinetics in shape-memory microfluidics are measured under several operating modes. Perfusion-assisted delivery of stimulus to the bulk volume of shape-memory microfluidics dramatically accelerates shape recovery kinetics compared to devices that are not perfused. The recovery times are 4.2 ± 0.1 h and 8.0 ± 0.3 h in the perfused and non-perfused cases, respectively. The recovery kinetics of the shape-memory microfluidic devices operating in various modes of stimuli delivery can be accurately predicted through finite element simulations. This work demonstrates the utility of vascularized materials as a strategy to reduce the characteristic length scale for diffusion, thereby accelerating the actuation of stimuli-responsive bulk materials.