Page 164 - Read Online

Wang et al. Soft Sci. 2025, 5, 28 https://dx.doi.org/10.20517/ss.2025.11 Page 15 of 29

Performance enhancement strategies
Highly sensitive sensors can detect small stimulus changes, improving signal-to-noise ratio and accuracy.
Thus, enhancing the sensitivity of sensing arrays is usually the focus of researchers’ attention. In this
section, we summarize strategies for improving the sensitivity of sensor arrays from other studies. Luo et al.
inspired by the interface contact behavior of gecko’s feet, designed a slant hierarchical microstructure to act
as an electrode contacting with an ionic gel layer, fundamentally eliminating the pressure resistance and
maximizing functional interface expansion to achieving ultrasensitive sensitivity. Such a structuring strategy
dramatically improves the relative capacitance change both in the low- and high-pressure regions, thereby
boosting the sensitivity up to 36,000 kPa and effective measurement range up to 300 kPa . Liu et al.,
-1
[37]
inspired by the sensitive microstructure of human skin (protective epidermis, spinous sensing structures,
and neural conduction networks), prepared a self-healing, recyclable, and antibacterial polyurethane
[105]
elastomer matrix via templating . This matrix was integrated with microparticle arrays coated with
conductive MXene nanosheets to create a biomimetic skin multifunctional sensor. Thanks to the
polyurethane elastomer matrix’s excellent mechanical properties and the sensor’s unique skin-like
microstructure, the resulting electronic biomimetic skin exhibited outstanding sensing performance for
human health monitoring. It achieved an ultrahigh sensitivity of 1,573.05 kPa within a 50 kPa detection
-1
range. Experimental verification confirmed that the device could successfully detect human activities such
as pulse, speech, finger bending, and gait. Gang Li et al., drawing inspiration from the filiform papillae on
cat tongues, developed a flexible pressure sensor with a sensitivity of 504.5 kPa -1[36] . The authors introduced
a novel stress-transfer strategy to achieve this high sensitivity. As shown in Figure 10C, the flexible pressure
sensor array consists of two CNT/PDMS (CNTs/PDMS) micro-structured arrays integrated face-to-face,
forming an interlocking structure. This filamentary structure can continuously shift the stress concentration
position under increasing loads, preventing structural compressibility reduction from stress accumulation,
thus maintaining high sensitivity within its detection range. Additionally, experiments confirmed the
developed flexible pressure sensor array’s capability to monitor human physiological signals and motion
states, making it suitable as a human-machine interaction interface. The sensitivity enhancement of sensor
arrays mainly relies on microstructures. Both aforementioned works adopted a biomimetic approach to
fabricate high-sensitivity sensor arrays, providing valuable references for future high-sensitivity sensor
manufacturing.

Most sensors have sufficient sensitivity for common applications. However, a significant issue in mechanical
sensors is the trade-off between sensitivity and sensing range, particularly in pressure sensor arrays.
Typically, high-modulus materials are used to achieve a large measurement range, which greatly reduces
sensitivity. In contrast, high-sensitivity sensor arrays often have a detection range of only kilopascals due to
innovative structural designs, failing to meet higher detection needs. Chen et al. used conical carbon foam
arrays as the sensing layer and elastomer shims as stiffness regulators, achieving a high sensitivity of
24.6 kPa and an ultra-wide linear range of 1.4 MPa . To realize high sensitivity, they adopted double-
[38]
-1
sided pyramidal carbon foam arrays with conical microstructures and micro-porosity, which enhanced the
piezoresistive sensitivity of the carbon-foam-based sensing layer. Its hierarchical 3D porous structure and
high compressibility gave it highly nonlinear piezoresistive properties. To expand the pressure sensing
range, a stiffness regulator (SR) was introduced around the sensing layer to adjust the load distribution. The
SR’s nonlinear elasticity with the sensing layer’s piezo-resistivity achieved the piezoresistive pressure
sensor’s wide detection range. Similarly, inspired by this work, Xiang et al. proposed a multiscale design for
an all-carbon wearable PRSA, achieving high sensitivity and a wide linear range . The array used double-
[39]
sided pyramidal carbon aerogels (DPA) with pyramidal and porous microstructures as the sensing layer. A
silicone framework as an elastic support (ES) effectively distributed loads and expanded the linear range.
Additionally, conductive graphene sheets were transferred to superhydrophobic nylon fabric to form
breathable conductive substrates (BCS). This PRSA, made of all-carbon components, had a simple