Sensor-enabled RFID system for monitoring arm activity in daily life

After stroke, capacity to carry out tasks in the treatment setting with the more-affected arm is a poor index of actual use of that extremity in daily life. However, objective methods currently available for monitoring real-world upper-extremity use only provide information on amount of activity. These methods, which rely on movement sensors worn by patients, do not provide information about type of activity (e.g., functional vs. nonfunctional movement). The benchmark testing reported here evaluated an approach that involves placing sensors on patients and objects. An accelerometer and the transmitter component of a prototype radio frequency proximity sensor were attached to household objects. The receiver component was placed on the experimenter's right arm. This device triggered an on-board radio frequency identification tag to signal proximity when that arm was within 23 cm of the objects. The system detected > 99% of 6 cm or greater movements of objects. When handling of objects by the right or left arm was determined randomly, 100% of right arm trials were detected. No signals were recorded when objects were at rest or moved by the left arm. Testing of this approach, which monitors manipulation of objects (i.e., functional movement), is now warranted in stroke patients.