Natural rubber and epoxy resins are often chosen to protect the nanostructure and improve interface bonding properties. 2) Film material: usually the sensitive material of the flexible sensor, according to the different needs of the measured information can be used metal, conductive oxide, nanocomposite materials and so on. The metal film can retain the flexible characteristics of the substrate, but also can change the surface characteristics obviously. Transparent conductive oxide (TCO) films have both optical transparency and good electrical conductivity in the visible range, and have the advantages of folding, light weight, easy transportation and large-scale production, among which indium tin oxide (ITO) is more commonly used (with high visible light transmission, high infrared reflectance and low resistivity). Gallium or aluminum doped KJ3204X1-BA1 ZnO (GZO or AZO) is also widely studied and applied; Nanomaterials were initially used on sensors in the form of ultrafine particles, and in recent years have gradually expanded to low-dimensional materials and array materials, such as carbon nanopowder composite films, carbon nanotube composite films, carbon nanotube/carbon black/silicone rubber composite arrays, etc. 3) Electrode material: In addition to a small number of flexible sensor film materials and electrical electrodes, electrode materials are also the main components of flexible sensors, which use different materials and manufacturing processes according to different requirements, including carbon materials (graphene, carbon nanotubes, carbon fiber, etc.), metal nanowires (silver nanowires, copper nanowires, etc.) and conductive polymers (polyaniline, etc.), etc. Among them, carbon-based nanomaterials show outstanding development prospects, which are usually combined with various polymers to obtain flexible and stable strain sensors.

Compared with ordinary sensors, flexible sensors have better performance. KJ3204X1-BA1 The hard and brittle nature of ordinary sensors makes it difficult to bend and extend, and the measuring range is therefore limited. Flexible sensors use superior materials such as carbon nanometers, graphene, polymer membranes, polymer electrolytes and organic polymers to greatly improve ductility and other properties and adapt to complex uneven surfaces.

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Flexible sensors can be divided into three main categories according to the signal conversion mechanism: capacitive, resistive and piezoelectric. 1) Capacitive flexible sensor: When the external pressure is felt, the capacitance value between the electrode plates will be changed, resulting in changes in other electrical signals, so as to calculate the size of the external force by measuring the change in the electrical signal. Generally, capacitive flexible sensors add a layer of micro-structured dielectric material in the middle of the flexible electrode. Under the action of external pressure, the microstructure of the dielectric layer will change significantly, causing the dielectric properties of the dielectric material to change, resulting in a more obvious change in the capacitance value. Capacitive flexible sensors generally improve their sensitivity by changing the material of the dielectric layer or KJ3204X1-BA1 carrying out related structural modifications, or by combining the flexible substrate with a material with high dielectric constant. 2) Resistive flexible sensor: The working principle is to convert the external pressure value into a resistance or current value of the device. According to the different working principles, it is divided into strain type and piezoresistive type. When the strain gauge flexible sensor is stretched or compressed by external pressure, the cross-sectional area of the conductor changes, and the conducting area also changes, resulting in a change in resistance. Piezoresistive flexible sensor is based on piezoresistive effect sensor, when subjected to external pressure, the conductivity of the conductor material will change with some small changes in itself. 3) Piezoelectric flexible sensor: It is a sensor designed based on the principle of piezoelectric effect KJ3204X1-BA1 of piezoelectric materials. The so-called piezoelectric effect means that when some dielectric is deformed by external forces in a certain direction (including bending and stretching deformation), the internal polarization phenomenon is generated, and at the same time, the opposite charge is generated on some two surfaces. When the external force is removed, the dielectric returns to the uncharged state. When the direction of the external force changes, the polarity of the charge also changes, and the amount of charge generated by the force on the dielectric is proportional to the size of the external force. In this process, the magnitude of the external force can be calculated by the magnitude of the current.