A proof-of-concept prototype of a wearable weight sensing and feedback device was designed and constructed. This device is intended to be used by patients with injuries to a leg, hip, or foot who have been prescribed a physical therapy regimen in which a limited amount of weight is to be applied to the affected limb to speed recovery. The prototype consists of a shoe with weight- sensing insole, processor box, and a cord linking the two components. The prototype is relatively small, low-cost, self-contained, and fully functional and was constructed using readily available off-the-shelf components. The device permits the user to set the maximum allowable force, and an LED, buzzer, and insole vibrator alert the user when he or she exceeds the maximum force. Each alert mode is switchable, and the prototype also displays the applied weight on a seven-segment LED display. Piezoresistive pressure sensors embedded in the shoe insole are used to detect applied weight. A BasicATOM-28 microprocessor is used to process inputs and outputs to the system. No products with identical functionality currently exist on the market, but several existing patents may preclude cost-effective mass-marketing of the product.
