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Page 2 of 25 Lin et al. Soft Sci 2023;3:14 https://dx.doi.org/10.20517/ss.2023.05

INTRODUCTION
In recent years, advances in materials and manufacturing approaches have inspired a diverse set of soft
[1-7]
electronics and robotics with performances comparable to conventional rigid devices . The flexibility and
stretchability of these soft systems offer tremendous potential applications in many aspects, including but
not limited to electronics/optoelectronics, microelectromechanical systems (MEMS), energy harvesting and
storage devices, electronic switches, healthcare monitoring systems, and other biomedical tools [8-17] .
Compared to rigid devices, soft electronics with mechanical similarity to biological tissues ensure intimate
contact at the interface, enabling high-quality data acquisition with reduced noise and artifacts [18-20] . For soft
robotic systems, including soft actuators, major advantages involve capabilities of adaption, continuous
deformation, environmental responsiveness and less damage to delicate objects [21-26] . The soft form factor of
these systems also allows them to withstand bending, stretching, folding, and other means of mechanical
deformations [27-29] , thus providing possibilities for further miniaturization/integration and expanding the
application scenarios to electronic textiles, sensory skins, and minimally invasive surgeries [30-38] .

Among various types of functional materials exploited in soft electronics and robotics, magnetic materials
are of interest due to their unique properties in sensing and actuation. Compared to conventional magnetic
materials, magnetic nanomaterials demonstrate some unique advantages. Firstly, magnetic materials in the
form of nanomembranes or nanostructures can produce magnetoresistance (MR) effects, thereby
expanding the sensing ability of magnetic sensors [39,40] . Secondly, magnetic materials at the nanoscale show
size-dependent coercivity, offering great potential for programmable deformation and tunable torque.
Thirdly, mixtures of magnetic particles/nanowires and polymer matrices exhibit low effective modulus and
can be magnetized in a programmable format through advanced manufacturing approaches, creating a
diverse set of soft structures with enhanced capabilities in sensing and actuation. Incorporating these
magnetic nanomaterials into soft electronic systems allows for the detection of the intensity and/or
[41]
direction of magnetic fields generated from the earth or human body [42-44] , providing opportunities for
wearable navigation and fundamental studies of electrophysiology [45-47] . In robotic applications, besides the
advantages of remote controllability and transparency to biological tissues [48-51] , magnets in nanoscale or
mixed in polymer matrix can possess programmed magnetization profiles to produce various complex
deformations and abundant motion sequences [52-55] . Further developments in magnetic nanomaterials can
continue to promote the performances and broaden the functions of soft electronics and robotics.

A series of reviews, in a general sense, have covered topics ranging from nanomaterials-enabled electronics
and robotics [56,57] to mechanisms and materials of magnetic devices [58-60] . While many review articles have
provided valuable insights into the development of materials, structures and manufacturing approaches for
soft electronics and robotics, few have focused specifically on soft electronics and robotics based on
magnetic nanomaterials. Recent works have shown that magnetic nanomaterials have the potential to
expand the functions or promote the performances of many electronic and robotic systems in areas such as
biomedicine, sensing, and human-machine interaction. Therefore, this review article aims to discuss
magnetic nanomaterials and their applications in soft electronics and robotics to provide an overview of the
latest developments in this field. In Figure 1 and Table 1, we categorize magnetic nanomaterials into two
groups: magnetic nanomembranes/nanostructures (i.e., materials with thicknesses in nanoscale or with
nanoscale patterns) and magnetic composites (i.e., mixtures of polymer matrices and magnetic particles).
Sections “Soft electronics based on magnetic nanomembranes/nanostructuresand” “Soft electronics based
on magnetic composites” introduce the progress of soft electronics based on magnetic nanostructures/
nanomembranes and magnetic composite materials, respectively. Sections “Soft robotics based on magnetic
nanomembranes/nanostructures” and “Soft robotics based on magnetic composites” continue to describe
the applications of magnetic nanostructures/nanomembranes and magnetic composites, respectively, with a