A Wireless Wristband Accelerometer for Monitoring of Rubber Band Exercises

Here, we report a highly sensitive capacitive printed accelerometer and its wearable wristband module for wireless activity monitoring application during rubber band exercise. The printed accelerometer is modified to possess a high sensitivity of 0.54 pF/g, which shows promising reliability for human’s exercise monitoring. The circuit of the wristband exercise module is integrated into the customized printed circuit board so that the module receives and digitizes analog capacitance data from the accelerometer and wirelessly transmits the data to the receiver module on the user interface. Different force levels of exercises were successfully quantified with a distinctive capacitance variance from 0.031 pF under light exercise condition (16.04 N) to 0.266 pF under strong exercise (23.04 N). In addition, three different representative exercise postures were performed with the wristband module: 1) shoulder flexion; 2) horizontal arm abduction; and 3) knee extension. By sampling exercise data with 10 Hz, the module cannot only read the movements of the different exercise postures successfully, but also provide reliable collection of data that can be used to differentiate the exercise characteristics in each posture. The reported wristband exercise-monitoring module utilizes highly sensitive accelerometer and wirelessly communicating unit to provide point-of-care and high level of freedom to users during the rubber band exercises further suggesting feasibility of its potential usages in the other activity monitoring applications.