Persistent peak efficiency of bio-inspired pulsatile pumps

Paul Baisamy
PhD student
University of Edinburgh, UK
Lab webpage:

Non-continuous flow is ubiquitous in nature and widespread across biological systems of different type and size scales (human heart, cephalopods’ mantles, dragonfly nymphs, froghoppers…) Despite their widespread occurrence in nature and evidence of unparalleled performances, rotative machinery delivering a continuous flow is mainly used. However, there are several instances where the capability to generate impulsive, peristaltic and pulsatile flow would be beneficial. In underwater propulsion, propellers allow for maximum efficiency at only one specific cruising speed and are far from ideal for accurate maneuvers at low speed whereas pulsatile thrusters offer promising results. In the bio-medical field, rotative systems for cardiac assist device are unfit to efficiently generate discontinuous flows which often leads to major and well-known complications for the patients. More generally, the ability to produce highly unsteady flows represents a valuable asset in the adoption of soft robots at an industrial level. As an example, fluidic circuitry is a promising candidate to replace electronics in those environments where traditional solutions are suboptimal, such as nuclear sites or in the benthic layer of the oceans.

We present an analytic model of a bio-inspired pump having a mode of actuation reminiscent of the pulsed jetting operation of the myocardium or the mantle of squids and octopuses. The model, validated with experimental data, highlights key design parameters for sustained peak efficiency over a broad range of pulsation regimes. In particular, we demonstrate that, at resonance, the efficiency scales linearly with the actuator’s amplitude of deformation. The model gives a powerful tool for identifying design and control strategies in order to develop improved hydraulic actuators with analogous mechanical features.


Paul is a former R&D engineer in the biomedical field, he is now doing a PhD at the University of Edinburgh with the Center for Doctoral Training in Robotics and Autonomous Systems. He studies how systems in the medical field, in underwater robots or systems using fluidic circuitry can benefit from non-continuous flows. In particular, he looks at how we can use resonance and variable stiffness to design and control highly efficient robotic devices.