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Bar-Cohen : Biomimetics: Biologically Inspired Technologies DK3163_c009 Final Proof page 243 21.9.2005 3:10am

9

Engineered Muscle Actuators:
Cells and Tissues

Robert G. Dennis and Hugh Herr

CONTENTS
9.1 Introduction ........................................................................................................................................ 244
9.2 Systems Engineering of Living Muscle Actuators ............................................................................ 245
9.3 Muscle: Nature’s Actuator ................................................................................................................. 245
9.3.1 Potential Classes of Living Muscle Actuators...................................................................... 246
9.3.1.1 Whole Explanted Muscles.................................................................................... 246
9.3.1.2 Recellularized Muscle Extracellular Matrix ........................................................ 247
9.3.1.3 Muscle Cultured in an Artificial Matrix............................................................... 247
9.3.1.4 Self-Organized Muscle Tissue Engineered In Vitro ............................................ 248
9.4 Biomechatronics: Why Use Living Muscle in Machines? ................................................................ 248
9.5 Quantitative Assessment of the Function of Living Muscle Actuators............................................. 249
9.5.1 Efficiency (Volumetric, Metabolic, Excitatory)................................................................... 249
9.5.1.1 Volumetric ............................................................................................................ 249
9.5.1.2 Metabolic (Chemomechanical Transduction) ...................................................... 249
9.5.1.3 Excitatory (Excitation–Contraction Coupling) .................................................... 250
9.5.2 Static Contractility ................................................................................................................ 250
9.5.3 Dynamic Contractility........................................................................................................... 250
9.6 Practical Considerations for the Use of Living Muscle Actuators.................................................... 251
9.6.1 Fuel Sources.......................................................................................................................... 251
9.6.2 Failure Modes........................................................................................................................ 251
9.6.2.1 Septic Degradation of Tissue Structure................................................................ 251
9.6.2.2 Mechanical Failure within the Tissue (Intracellular, ECM)................................ 252
9.6.2.3 Mechanical Failure at the Tissue Interface .......................................................... 252
9.6.2.4 Metabolic Failure.................................................................................................. 252
9.6.2.5 Cellular Necrosis and Programmed Cell Death................................................... 252
9.6.2.6 Fatigue (Mechanical and Metabolic).................................................................... 253
9.6.2.7 Toxicity................................................................................................................. 253
9.6.2.8 Electrochemical Tissue Damage .......................................................................... 253
9.6.2.9 Damage from Incidental Mechanical Interference............................................... 253
9.6.2.10 Retrograde or Arrested Phenotype (Failure to Thrive)........................................ 253
9.7 Self-Organizing Muscle Tissues ........................................................................................................ 254
9.8 Acellularized–Recellularized ECM Engineered Muscles.................................................................. 255
9.9 Tissue Interfaces: Tendon, Nerve, and Vascular ............................................................................... 256

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