A microprocessor-based data-acquisition system for measuring plantar pressures from ambulatory subjects

A portable microprocessor-based data-acquisition system developed to measure discrete plantar pressures within the shoe from ambulatory subjects is described. The system offers improved accuracy, repeatability, portability, and flexibility not available in current commercial systems. It consists of 14 conductive polymer pressure sensors, 14 analog amplifiers, an 8-b analog-to-digital converter, a microprocessor, 120 kB of memory space, and a parallel I/O interface. Seven pressure sensors are embedded within each insole and located at the posterior heel, anterior heel, the four metatarsal heads, and hallux of each foot. The system is capable of continuously sampling 14 channels of pressure data for 7 min at a 20-Hz sample rate. The recorded data are downloaded into a microcomputer for further processing, analysis, and display. Foot pressures have been acquired from a sensate subject during multiple walking trials.