The present invention relates to wearable devices. Wrist belt type sensor, it provides for measuring wrist tendon power corresponding to specific finger movement, sensor includes: one or more piezoelectric transducers, the electric current that piezoelectric transducer generates, wherein one or more of transmittings are in pressure from wrist tendon one or more piezoelectric transducer It is configured to convert the electric current of generation with processing module from wrist tendon to signal and to handle signal in pressure and identify one or more specific finger movements. It is also provided for detecting specific finger movement based on wrist tendon power.
