A knitted smart sneaker system based on piezoresistive strain sensing for stride counting

Currently, smart shoes are not as common as other wearable devices such as fitness trackers or smartwatches. However, with the continuous improvement in sensor and IOT technologies, it is expected that shoes with smart capabilities will catch up with the other popular wearables. The emergence of 3D knitting and its subsequent application in footwear manufacture has revolutionized the shoe manufacturing process. The use of knitwear allows for shoe parts such as the upper or the sole (insole, Strobel sole, midsole and/or outer sole) to be tailored with specific areas having different characteristics and providing different functions with low production effort. This study presents the design and manufacture of a knitted smart sneaker for cadence mensuration. The specified part of the sneaker is knitted with silverplated polyester yarn to serve as a strain sensor. During the weight-bearing and release phases of the foot, while walking, this strain sensor is stressed and relaxed by this oscillatory phenomenon thus allowing footstep data to be measured. Stride estimate tests were carried out and the results established that strides taken by a user can accurately be correlated to the readings of the system. This study is the first to develop a smart shoe-sensing system where the sensor is inherently embedded within the shoe upper.