Wearable body area sensor networks for continuous dynamic health monitoring in daily activities: Case study of intelligent footwear system

The specific cares for elderly people and patients with chronic diseases have placed an increasing burden upon public healthcare systems, which calls for a continuous dynamic monitoring in daily activities to save time, cost and human resources as well as to prevent diseases in early stage. Most current technologies, however, are restricted in research laboratories or hospitals, and not reliable for continuous monitoring in everyday life, due to incomparability in rigidity of sensors and skin, heavy and bulky nodes and power sources, and complicated operations in body area sensor networks. The present work is aimed to design a wearable body area sensor network and implement a case for continuous dynamic monitoring in healthcare, based on investigations of various enabling technologies including textile sensors and body area sensor networks (BASNs). A suitable electronic interface for nano-carbon silicone composite textile sensors was presented, and a novel textile sensor matrix readout method was proposed which achieved a small crosstalk error (0.6%). They were adopted in a single-node in-shoe plantar pressure measurement and analysis system. In order to achieve multi-node networks, Bluetooth based BASN was investigated for its superior compatibility with mobile computing devices. A model for delay estimation of this BASN was established by calculation of time cost in each component, layer and process of total networks, involving distribution hypothesis, Poisson process analysis, and optimized configuration. The average difference in sampling frequency between experimental and simulation results was 5.73%. The intelligent footwear system, as a case of wearable BASN for continuous dynamic monitoring in daily activities, was then developed. It collects, during daily activities, foot information including plantar pressure, in-shoe temperature and humidity, centre of pressure (COP), and 3-axis foot accelerations. It demonstrated satisfactory accuracy, repeatability, and wearing comfort, and has been used for daily dynamic foot monitoring of human subjects. The obtained data provides new knowledge on foot conditions, life style and physiological status of the subjects, much needed for prevention, diagnosis and therapeutic treatments of foot disease, e.g., diabetic foot syndrome, athletic training, rehabilitation, as well as signalling of overweight.