<p>In this study, we propose a novel wearable device to detect the motion of the lower limb using tendon-inspired piezoelectric sensors. The wearable device comprised twelve tendon-inspired sensors and body supports to fix the sensors at the lower limb joints. Specifically, to observe lower limb movements with the device, we detected six reference movements per leg and estimated the angle of each lower limb joint using the measured data from the attached sensors at the joints. To validate the reliability of the measured data from the lower limb device, repetition experiment was conducted in conjunction with theoretical analysis. Furthermore, we converted the measured data to estimated angles using numerical integration. By comparing the estimated angles with actual angles measured by infrared trackers, we have good agreement between the sensing values and the joint angles. Using the wearable device, we developed a motion detection system with a virtual avatar to demonstrate the potential application of the device in human imitation technology.</p>