Customized foot pressure redistribution insole design using image-based rapid pressure measuring system

Traditionally, technician fabricates the medical foot pressure redistribution insole used in rehabilitation for diabetic patients manually. The first step is to use silicon or clay material to identify the shape and size (rubbing) of subject's foot. After that, a clay mould is then produced by the rubbing of foot feature. According to the clinical diagnosis and foot pressure redistribution therapeutic protocol, the clay mould is modified subjectively by technician. The resin of medical insole is then produced with fixed shape and size. The drawbacks of abovementioned process are that profile of insole is irreversible and it is lack of quantitative measure for producing insole. In the paper, a customized adaptive multi-airbag foot pressure redistribution insole design and manufacturing methodologies using image-based rapid pressure measuring system is proposed. The in-house made rapid foot pressure measurement system is constructed with a body weight spring scale and an image-based foot/ground contact pattern identification scanning mechanism. The basic principle of measuring system is that, when the body weight was supported by foot, the blood will be blocked into the blood capillary of sole and it will generate the different color foot/ground contact pattern owing to the difference of local contact pressure. By using scanning mechanism, the contact pattern is registered and foot pressure distribution profile can be easily calculated by using a mathematical transformation model. A two-layered insole with multiple channel air-inflated bags in the bottom layer for adjusting foot contact pressure is proposed. In this configuration, the correct contact foot pressure profile can be achieved by pumping air into each air-inflated bag when subject is standing on the insole. An adaptive multi-air-bag insole using proposed method was designed and constructed. The proposed method not only can be used for the design and manufacturing for medical therapeutic insole but also for athletic and personal insole.