  Artificial microswimmers, nano and microrobots, are essential in many
applications from engineering to biology and medicine. We present a Stokesian
Dynamics study of the dynamical properties and efficiency of one of the
simplest artificial swimmer, the three linked spheres swimmer (TLS),
extensively shown to be an excellent and model example of a deformable
micromachine. Results for two different swimming strokes are compared with an
approximate solution based on point force interactions. While this
approximation accurately reproduces the solutions for swimmers with long arms
and strokes of small amplitude, it fails when the amplitude of the stroke is
such that the spheres come close together, a condition where indeed the largest
efficiencies are obtained. We find that swimmers with a "square stroke cycle"
result more efficient than those with "circular stroke cycle" when the swimmer
arms are long compared with the sphere radius, but the differences between the
two strokes are smaller when the arms of the swimmers are short. This extended
theoretical research of TLS incorporates a much precise description of the
swimmer hydrodynamics, demonstrating the relevance of considering the finite
size of the constitutive microswimmers spheres. This work expects to trigger
future innovative steps contributing to the design of micro and nanomachines
and its applications.
