Prosthetic arm monitoring system using a programmable interface controller

Children with upper extremity limb deficiency are often prescribed a prosthetic arm to assist with daily function. Three types of prostheses are available: passive, active body-powered, and active myoelectric; costs range from $3,000 to $15,000. Clinicians rely on parent and child feedback regarding the usefulness of the prosthesis, and may assess the child's skill in using the device in a controlled setting. However, these methods do not provide an objective quantification of the wear and use of the device during daily activities. The purpose of this project is to develop a sensor to record the amount of time per day the prosthetic arm is worn, and to count the number of times per day the child activates (closes) the prosthetic hand (or terminal device). The system that has been developed can be integrated unobtrusively into a child's prosthetic arm. A programmable interface controller (PIC) with interface circuitry and memory was developed to record the daily wear pattern and hand usage of the prosthesis at 15-minute intervals. Memory and battery capacities are sufficient to record data over a three-month period. A personal computer interface downloads the collected data and may be used to reprogram the device for different time periods of data collection. All components, including the battery, have a mass of 87 grams and fit inside the forearm cavity of a 9-year old's prosthesis. Controlled trials are underway at Shriners Hospital for Children, Northern California, to determine system reliability.