Wearable technology has attracted much attention from academia and industry due to its potential application value in various fields such as healthcare, human-computer interaction, and the Internet of Things. Flexible pressure sensors are an indispensable part of wearable devices, which can reflect signals such as pressure intensity, duration, interval, and frequency. They have the characteristics of high flexibility, low cost, and are suitable for highly integrated applications. The microstructure design of sensing materials largely determines the specific surface area, deformable space, and deformation ability of the active layer, which has a significant impact on the sensing performance of the device. Therefore, the research on microstructure engineering of sensing materials has important theoretical value and innovative significance, which will greatly assist the design and development of flexible pressure sensors.

At present, according to different sensing mechanisms, flexible pressure sensors can be mainly divided into resistive, capacitive, transistor, piezoelectric, and frictional types (Figure 1). Resistance pressure sensors mainly convert pressure stimuli into resistance or current changes for output. Capacitive pressure sensors are based on the capacitance changes of the active layer under pressure, and commonly used sensing materials include electrodes constructed with conductive materials and polymers, as well as dielectric layers constructed with low modulus materials. The working principle of a transistor based pressure sensor is to induce pressure to regulate the flow of charge carriers between the source and drain electrodes. In piezoelectric sensors, the instantaneous electrical signal generated by piezoelectric materials can be used for monitoring external pressure. Common piezoelectric sensing materials include piezoelectric crystals, piezoelectric polymers, bio piezoelectric materials,

piezoelectric peptides, and their derivatives. Friction electric pressure sensors work based on the coupling effect of electrostatic induction and contact electrification, and their output signals are related to the magnitude, velocity, contact area, and material properties of the contact force.

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