Page 48 - Read Online

Page 4 of 35 Villeda-Hernandez et al. Soft Sci 2024;4:14 https://dx.doi.org/10.20517/ss.2023.52

Table 1. Summary of common muscular actions and the average force and power generated in contrast with pump-driven and
chemically driven soft pneumatic actuators
Typical average force (N)
Action Ref.
Male Female
Natural muscular actions
a
Force to stand (one leg) 800
Overhead seated pull 400* 222* [40]
Overhead standing pull 400* 244*
Straight push seated 227* 96*
Straight push standing 251* 140*
Contracting quadriceps (no age range) 460 ± 159 [41]
Hand grip left (20-29) 454 ± 94 254 ± 52 [42]
Hand grip right (20-29) 486 ± 87 285 ± 64
Anal sphincter 7 [43]
Power (W)
Plantar flexors extension 630 ± 13 [44]
Knee extensors 606 ± 30
Hip extensors 2,037 ±181
Soft robotics
Force (N)
High-force soft pneumatic actuator 70 [45]
Chemo-driven pneumatic actuator 15 [31]

a [46]
Based on the average weight of a person in Europe as 80 kg ; *no error given as taken over a range of angles for the subjects and averaged.

of bellows-type pneumatic actuators surrounding the soft tissue emulates the peristaltic contraction
movements through their linear motions when pressurized. Chen et al. described the development and
arrangement of soft grippers that mimic the bending and twisting motions of a human wrist, providing
[51]
precision and fine control for tasks such as delicate goods handling.

Geometry is a fundamental part not only of the motion achieved by soft pneumatic systems but also of their
control and deployment. Origami, kirigami, and kerf patterns have served as inspiration for achieving
controlled and tunable actuation [52,53] . Jin et al. reported soft pneumatic actuators with programmable shapes
using various kirigami patterns through computational optimization strategies . Furthermore, Melancon
[54]
et al. developed large-scale multi-stable inflatable structures that lock in place after deployment by
integrating bistable origami shapes into the associated pneumatic actuators . They also developed modular
[55]
[56]
origami structures with different stabilities to achieve controlled and tunable motions . The significant
advances in the design and control of soft pneumatic systems, as reported by Jin et al. and Melancon
[54]
et al. , undeniably showcase the vast potential of these systems [Figure 3]. The ability to achieve motion,
[56]
control, and deployment in these systems, particularly those designed for portability, hinges critically on the
power source. A major challenge for these and related systems is, therefore, the on-demand availability of
portable pneumatic power sources. As these soft pneumatic systems become more compact and efficient,
the need for compatible, lightweight, and efficient power sources becomes increasingly apparent to allow
wide application of this approach.

Power sources
Despite the numerous advantages of soft pneumatic systems derived from their fluid-driven nature in terms
of tunability, applications and design, these systems tend to rely on heavy, rigid, and non-portable power
sources [57-59] . Commonly used conventional power sources include air compressors and pumps. These