Research progress of the plantar pressure monitoring system for gait analysis

With the aging of the population in China, people's demand for health monitoring is gradually increasing. As an effective way of health monitoring, gait analysis is increasingly widely used in disease diagnosis, fall prevention, rehabilitation, human-computer interaction and other fields. Gait reflects the interconnectedness of multiple physiological systems, including balance, strength, and cardiovascular capacity, and a person's gait can tell us a lot about their health. Gait analysis is a systematic study of human walking movements and an important evaluation tool for analyzing individual life signals, which can be accomplished by collecting, describing and characterizing kinetic and mechanical data of gait. Firstly, this paper introduces the importance of gait analysis and the research status of plantar pressure monitoring, as well as the characteristics of various plantar pressure monitoring systems. Secondly, the physiological characteristics of the foot are summarized, including the common division methods of the center point of plantar pressures and gait phases. Then, the materials and characteristics of the key device for gait analysis data acquisition, flexible pressure sensors, are systematically analyzed. In the meantime, integration and connection modes of sensors, and common step recognition algorithms are also summarized. Detailedly, according to the sensing principle, the flexible pressure sensor can be divided into piezoelectric, capacitive, piezoresistive, triboelectric, photoelectric, magnetic induction and pneumatic flexible pressure sensors. Piezoelectric flexible sensors do not require external power supply, have high sensitivity and long service life, but cannot monitor static forces, and the preparation process is more complicated than that of other sensors. The triboelectric sensor has advantages of various types, wide range of available materials, simple structures, self-power supply and good biocompatibility. The capacitive flexible sensor has the characteristics of high sensitivity and fast response, but its portability is poor and easy to be interfered by environmental factors. The piezoresistive sensor has good flexibility and high sensitivity. The photoelectric sensor has the characteristics of anti-electromagnetic interference, high sensitivity, light weight and so on. The magnetic induction sensor has high conversion efficiency and fast response ability, but there are common errors caused by hysteresis, and it is very sensitive to external magnetic field interference. Pneumatic sensors are sluggish and bulky. Finally, the design direction and further research of the plantar pressure monitoring system are discussed. At present, although there have been a lot of research on gait analysis at home and abroad, the following three aspects need to be improved in order to realize large-scale and normalized gait monitoring. First, to meet the needs of customization, for some specific diseases and special populations, the system needs to be able to be flexibly adjusted. Second, formulate complete industry standards. For smart insoles, shoes and socks, to enable telemedicine services and long-term sole pressure monitoring, it is necessary to standardize the various principles of sensors and ensure the safety of long-term use. Third, improve data processing technology. Through the fusion of various algorithms, the feature classification and extraction of data are carried out to improve the accuracy of gait judgment and reduce the misjudgment rate. The Internet of Things technology is utilized to improve the efficiency of data processing and transmission, and obtain greater data storage space.