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3,000th cycles are essentially superimposable. Supplementary Figure 10 demonstrates the mechanical
performance of the sensor. Following 1,000 cycles of bending, the sensor exhibited consistent resistance
variation across cycles, demonstrating its excellent mechanical characteristics.

Sensing mechanism analysis
To further elucidate the intrinsic mechanisms behind the electrical conductivity and tensile properties of the
graphene-CNTs-TPU/fabric strain sensor, scanning electron microscopy (SEM) was utilized to characterize
the sensor’s morphological changes throughout the stretching process. Figure 3A (i) and (ii) displays the
microscopic morphology of the sensor in its pristine state (0% strain). The surface of the composite film is
devoid of any significant cracks and holes, characterized primarily by its texture. As the strain increases to
20%, incipient microcracks become visible on the surface, with widths measuring approximately 21.7 μm
[Figure 3B (i) and (ii)]. The stretching process causes the composite film to become thinner and narrower,
and compression by stress along the z-axis leads to a reduction in the gap between internal conductive
particles. The reduced spacing enhances the tunneling effect, thereby mitigating the impact on sensor
resistance from microcrack formation and the relative displacement of graphene and CNTs. Upon reaching
a 40% strain, the microcrack width expands to approximately 97.2 μm [Figure 3C (i) and (ii)]. The
predominant crack propagation mechanism leads to a marked increase in sensor resistance. Subsequently,
the stress is relieved, and the sensor reverts to its original length [Figure 3D (i) and (ii)]. Compared to the
initial state, it is evident that the microcracks on the composite film’s surface do not fully close, with a
remaining width of approximately 55 μm. Figure 3E delineates this dynamic process into three distinct
stages: the initial formation of microcracks (0% to 20%), the subsequent expansion of microcracks (20% to
40%), and the recovery phase of microcracks (40% to 0%). These surface micro-dynamic processes elucidate
the phenomenon of gradually increasing resistance during the stretching process. Furthermore, the
persistence of microcracks after the sensor is restored to its original length substantiates that the resistance
is higher than that of the unstretched state. A small number of unsealed micro-cracks are visible on the
surface, with the greatest crack width not surpassing 20 micrometers (µm) after 3,000 stretching cycles
[Supplementary Figure 11]. This observation attests to the composite film’s structural integrity, securing the
sensor’s reliability.

Application of human activities and healthcare monitoring
The graphene-CNTs-TPU/fabric strain sensor demonstrates high sensitivity, a low detection threshold,
outstanding durability, and responsive symmetry, providing a clear advantage in the realm of human
monitoring applications. Figure 4A-D illustrates the relative resistance changes as the strain sensor is affixed
to various joints and flexed at multiple angles. Based on the specific shape and dimensions of the joint,
strain sensors of varying sizes can be fabricated to facilitate bending monitoring. The results demonstrate
that the response signal range varies with different joint bending angles, highlighting the sensor’s
application potential in auxiliary training and motion recognition applications.

The sensor’s sensitivity to subtle vibrations was investigated. Initially, the sensor was affixed to the larynx
and linked to an integrated wireless testing system to detect subtle variations in laryngeal muscles during
vocalization. Figure 4E, F and Supplementary Figure 12 display the sensor’s responses upon repeating “Bye”,
“Hello”, “Goodbye”, and “Good Morning”, respectively. These results demonstrate that the sensor is
sensitive to laryngeal muscle vibrations and exhibits a consistent response to the same word or phrase. For
words with varying numbers of syllables, the response exhibits a degree of differentiation. Subsequently, a
simple wireless pulse monitoring system was assembled by positioning sensors over the radial artery and
incorporating a wireless measurement and transmission system [Figure 4G]. As depicted in Figure 4H, the
pulse beat elicits a specific response from the sensor. The illustration reveals that the response features
distinctive characteristic peaks, aligning with the known peaks of “Blow Wave P”, “Tide Wave T”, and