# Underwater Highly Pressure-Sensitive Fabric Based on Electric-Induced Alignment of Graphene
## 3 Results and Discussion
(**c**) Static and dynamic contact angles of the fabric after plasma treatment under different graphene concentrations; the inset shows the contact angle of the fabric after 50 rubbing cycles. (**d**) \(\Delta\)I/I\({}_{0}\) value of the flexible pressure sensor at 50 kPa after electric field induction; the inset is the I\(-\)V curve of the single-layer fabric under different electric field intensities. (**e**) I\(-\)V curves of the flexible pressure sensor under different static pressures after electric field induction. (**f**) Cycling test of the sensor under dynamic pressure after electric field induction. cured at different electric field strengths are all linear and through the origin, following [PERSON]'s law. The monolayer fabric still has a stable electrochemical output after being exposed to different voltages. From the slope of the I\(-\)V curves, the resistance of the fabric did not change significantly, indicating that the electric field had no obvious effect on the electrical conductivity of graphene nanosheets. As shown in Figure 3a,d, as the electric field was induced, the sensitivity \(\Delta\)I/I\({}_{0}\) of the sensor increased to approximately 55 and tended to be stable. This mainly depends on the deformation of the coating geometry. After orientation, the graphene coating has a fluffy and enlarged structure [18], and the adjacent graphene nanosheets generate tiny distances in space. The voids are mainly filled and supported by the PDMS elastomer (Figure 2b). Under the action of external force, the fluffy structure is deformed by force contraction, the nanosheets are in closer contact, the conductive paths are increased, and the \(\Delta\)I/I\({}_{0}\) value increases. However, after the voltage reaches 3 kV, the sensitivity of the sensor remains unchanged. This may be because torque and system resistance mainly affect graphene deflection in the electric field [27], indicating that the choice of voltage is an important starting point for realizing the torsion of graphene nanosheets. Conversely, we also applied a transverse electric field parallel to the coating direction. As illustrated in Figure S4, the response effect of the sensor decreases. We believe it is because the addition of the transverse electric field makes the stereospatial amplification structure disappear and there is no additional structural deformation under the external force (Figure S5). We then conducted a dynamic pressure test on the sensor assembled by the fabric after the action of the electric field. The I\(-\)V curves of the pressure sensor are also linear, and the resistance is stable under different external pressures, indicating that the sensor, after the electric field is applied, followed [PERSON]'s law and has good piezoresistive properties (Figure 3e). The cyclic stability of the fabric sensor was also tested after the electric field was applied. Figure 3f shows the sensing response under different external pressures. Notably, the pressure sensor has good repeatability and stable sensing response over a wide pressure range (2\(-\)100 kPa). The sensor effectively detects when the pressure is loaded from low to high. Likewise, the sensor detects the change in pressure from high to low. As well, at the same pressure, the pressure peak detection shows only a small drop (Figure S6). This shows that the sensing has good repeatability. However, it can be seen that when the pressure loaded exceeds 50 kPa, the sensitivity of the device to the pressure response decreases as the pressure continues to increase. This may be due to the structural deformation of the fabric reaching a critical value. To further discuss the practical use of the strain sensors, we also performed sensing tests on the superhydrophobic sensors in different underwater environments. This includes underwater crush detection, knockdown detection, and durability under extreme conditions [28]. As shown in Figure 4a, we pressed the sample in water, and the sensor produced a regular current response.