# Underwater Highly Pressure-Sensitive Fabric Based on Electric-Induced Alignment of Graphene
## 1 Introduction  
Wearable pressure sensors [1; 2; 3; 4; 5; 6; 7] have attracted much attention in human surface motion detection, biomedical detection, and electronic skin. Traditionally, there are three categories of pressure sensors: piezoelectric, piezoresistive, and pressure-capacitance. Compared with other types, piezoresistive pressure sensors [8; 9; 10; 11] have unique advantages, such as ease of manufacture and low energy consumption. In general, wearable piezoresistive pressure sensors are obtained by loading coatings on a flexible substrate that converts externally applied pressure or mechanical forces into changes in current or resistance through signals. However, current sensors still suffer from mild sensitivity or a lower service life in extreme environments. For example, for underwater monitoring, the sensor is attacked by water, and the device easily short-circuits, resulting in severe signal distortion in practical applications. Researchers have introduced superhydrophobic material on the sensor surface to improve its resistance to harsh conditions. For example, [PERSON] et al. [12] established a stable reduced graphene oxide/PPy/poly(dimethylsiloxane) (PDMS) polyurethane (PU) sponge (GPPS) sensor by the in situ reduction of graphene oxide and deposited polypyrrole nanoparticles grown on the sponge surface. [PERSON] et al. [13] successfully prepared a multifunctional flexible nanocomposite coating using multibranched polyurethane and silica nanoparticles modified with graphene. [PERSON] et al. [14] prepared a superhydrophobic conductive cotton fabric by impregnating a PDA/reduced graphene oxide solution with copperparticles grown in situ and then modified with stearic acid. Although the above sensors have good superhydrophobicity and detection performance, the sensitivity is moderate and the preparation process is relatively complicated. In addition, only a few studies have explored the effect of the spatial orientation and arrangement of interlayer graphene nanosheets on the sensor's performance. Notably, the contact area between graphene layers changes after the action of the electric field, which in turn improves composite interlayer properties [15]. This also greatly enhances the durability and cycle performance of nanocomposites. Therefore, the demand for multifunctional polymer nanocomposites is increasing. Furthermore, the graphene nanosheets have a tendency to be oriented and aligned in the polymer matrix under the action of external force, and the obtained nanocomposites have unique piezoresistivity. [PERSON] et al. [16] reported epoxy-graphite nanocomposites which were aligned along the electric field direction under the induced action of an AC electric field. The tensile modulus and strength of these materials were found to be anisotropic. [PERSON] et al. [17] prepared directionally oriented graphite nanosheets using an AC electric field and prepared polyester resin nanocomposites, and found that the conductivity of the composites along the directional orientation was significantly improved. [PERSON] et al. [18] prepared a vertical pressure sensor with a single graphene layer using a plasma chemical vapor deposition method. By introducing an amplification structure into the sensor, the detection capability of the sensor was successfully improved. [PERSON] et al. [19] constructed a novel MXene-based textile pressure sensor by assembling MXene on a hollow structured three-dimensional knitted fabric. The designed textile sensor has several excellent sensing properties, such as high sensitivity, fast response time, good stability (over 20,000 cycles), and excellent waterproof capability. In this experiment, a simple strategy was used to introduce an electric field into the preparation process of the conductive fabric to obtain a graphene interlayer-amplified structure. When an external force was applied, the additional structural deformation of the graphene sheet increased the sensor's output.