Dynamic and living devices for overcoming fibrosis of implanted biomaterials.

The fibrotic encapsulation of implantable medical devices reduces diffusion-based mass transport and electrical conductivity between the tissue and implant, limiting many devices to weeks-long rather than years-long lifetimes. Most strategies to overcome fibrosis take a passive, materials-driven approach to mitigate the chemical and mechanical mismatch at the tissue-implant interface through superficial or structural implant modifications. Recent advancements in microfabrication and mechanotherapy have led engineers to incorporate smart and active mechanical actuation systems into implantable devices that use pressure, vibration, and integrated electronics to perpetually overcome effects of the foreign body response. Here, we highlight medical applications where active antifibrotic strategies outperform passive strategies in terms of device lifetimes and therapeutic outcomes, outline engineering design considerations for integrating active strategies, and discuss challenges in developing dynamic and living implants.