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Wang et al. Soft Sci. 2025, 5, 28 https://dx.doi.org/10.20517/ss.2025.11 Page 21 of 29

[18]
(iFlexSense) skin with components analogous to skin, neurons, the immune system, and the brain . The
iFlexSense skin provides substantial improvements to aircraft through multifunctionality, including airflow
perception, state awareness, and self-diagnosis of complex surfaces. It was experimentally verified via wind
tunnel tests on a NACA0012 wing profile. Results showed the array could accurately measure pressure,
temperature, wall shear stress, and flutter on the wing surface, locate impacts, and predict flow separation
and stall. This work shows the great potential of sensor arrays in future wind tunnel tests and for enhancing
the capabilities of unmanned aerial vehicles and underwater vehicles. Chen et al. presented an ultrathin and
customized-crack strain-sensing network for strain monitoring, fabricated through transfer printed
technology. The sensor can be adhered to various curved surfaces to achieve long-term, high-fidelity strain
monitoring. The strategy was employed to fabricate the substrate-free sensing network, offering the
[113]
potential for improved capabilities for intelligent equipment . The above-mentioned research shows that
with the development of the IoT, flexible sensor arrays have gained wide attention in intelligent equipment
[Figure 14].

Flexible sensor arrays have a wide range of applications in human-machine interaction, such as health
monitoring and intelligent equipment. These applications require high sensitivity and resolution, as well as
stable electrical performance and structural integrity of the devices under long-term cyclic loading and
environmental exposure. These are the key factors that enable sensors to be used in real-world applications.
Sensor devices are typically subjected to long-term cyclic loading, which can be problematic due to material
fatigue and performance degradation. In addition, environmental factors such as moisture and ultraviolet
(UV) can also reduce the lifetime of the device. Therefore, to improve the reliability in real-world
applications, researchers are exploring more stable material systems, fatigue-resistant structural designs, and
effective packaging strategies to ensure that flexible sensing arrays can maintain stable sensing performance
in complex real-world environments. Li et al. developed an intelligent blood pressure and cardiac function
monitoring system based on a conformal and flexible strain sensor array and deep learning neural
networks . The sensor showed high stability and durability in long-term strain loading-unloading cycles
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because the elastic fabric electrode had a relatively stable resistance to mechanical deformation. Its
resistance increases by less than 1% of the whole system resistance even under 35% tensile strain. The
experiment result also showed no change in performance before and after the thirty-day cycle. This
demonstrates the reliability of the prepared sensor devices for practical applications. He et al. prepared a
high-precision CuO/TiO /MXene ethanol sensor operating at room temperature . The response tests of
[115]
2
the sensor were conducted six times every 7 days at 1, 5, and 20 ppm ethanol, respectively, indicating that
the sensor has good long-term stability, which is mainly attributed to the p-n heterojunction formed by
CuO and TiO , as well as the rich functional groups and large specific surface area of MXene. Luo et al.
2
propose an in situ post-processing approach utilizing electrochemical reactions between metals (Zn, etc.)
and hydrogels to synergistically achieve strong adhesion of the hydrogel-electrode interface due to the
structural densification of the hydrogel network . The prepared sensor demonstrates multimodal sensing
[116]
capabilities, encompassing highly sensitive strain perception and simultaneous perception of temperature,
humidity, and oxygen content unaffected by strain interference. Lee et al. developed an ultrathin and,
ultrasoft strain sensor comprising a PU nanomesh as a friction-protective layer and an Au on PDMS-PU
nanomesh as a strain-sensitive layer designed for on-skin applications . The Au on a PDMS-PU
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nanomesh layer demonstrated stable operation under various environmental conditions, including changes
in temperature and humidity and the presence of a saline solution. Gao et al. developed a novel
multifunctional conductive hydrogel based on methylcellulose and cellulose nanocrystals, which exhibited
excellent UV shielding behavior . Flexible strain sensors assembled by the prepared hydrogels can be used
[118]
to detect human body motions, including subtle and large motions, and exhibit good sensitivity and stability
over a wide temperature range with UV-filtering properties. The above studies offered various strategies to
the problems of long-term stability and reliability in real-world applications and exposed them to different