  This work presents a new fiberless soft pneumatic actuator that can work
multifunctional and bidirectional, and its embedded sensors give it a
self-proprioception ability. This actuator works based on the idea of employing
helical pressure channels. Applying the controlled input pressures into these
two channels causes a variety of deformations and actuation. In particular,
single pressure, imbalanced pressures, and balanced pressures applied in the
channels cause bidirectional coilings, opposite bendings, and elongation,
respectively, in a single unit actuator. Also, two U-shaped microchannels are
created, and by injecting a gel-based conductive material, the actuator is
equipped with resistive sensors which are responsive to a vast dynamic range
from a small oscillation to a large elongation. This actuator has so many
promising features as a multifunctional soft gripper, and its embedded soft
sensors enable it to have better controllability in real problems. The
multifunctionality of this actuator has been validated with several
experimental tests, and also we have shown it has excellent potential in
gripping a variety of objects. Finally, the embedded sensors can discriminate
the main functions of actuators, and also they can play the role of independent
sensors as well like a stretch, pressure, or bending sensors.
