Meeting Abstract

S3-4  Friday, Jan. 4 09:30 - 10:00  Trade-offs of power amplification on compliant substrates REYNAGA, CM*; AZIZI, E; Duke University; University of California, Irvine

From frogs to fleas, many biological systems utilize power amplifying mechanisms to achieve fast accelerations. Power amplification can have varied performance outputs using the same set of components. To better understand how the quality of the latch can optimize for varying conditions, we reduce the complexity of the system to a lower level of organization where we can independently control the latch dynamics and mechanical properties of the substrate. Here, we ask how latch quality and substrate stiffness affects elastic energy recovery from compliant substrates. We present a simple hypothetical model that explains key features of latch dynamics on compliant substrates. We test this model, which suggests less-rigid (less ideal) latches perform optimally on complaint substrates. We develop a reduced in vitro muscle preparation to test the performance of the latch mechanism on compliant substrates. We use the plantaris muscle-tendon-unit of a bullfrog (Lethobates catesbeianus) as the motor and spring in-series connected to two servomotors; one that simulates unlatching (rapid muscle shortening as a result of joint extension) and a second that simulates a reactive complaint substrate. We test elastic energy recovery during tendon recoil from various compliant substrates and latch velocities. We found slower latch velocities recover more energy from compliant substrates. Our work decouples the latching mechanism to test key features of latch and spring dynamics on variable substrates. We suggest ‘less-ideal’ latches may be most optimal for efficient performance on variable substrates regardless of relative compliance.