Wearable devices, methods and processor-readable media for multi-finger mid-air gesture recognition are described. A smart ring wearable device having an array of proximity sensors located about the circumference of the ring is used, in conjunction with a motion sensor such as an accelerometer, to sense and recognize multi-finger mid-air gestures. The proximity sensors may be used to sense the relative positions and shapes of the fingers of the user's hand. The motion sensor may be used to detect gross movements of the finger, hand, and arm, and to detect other movements such as finger collisions using high-frequency sampling of accelerometer data to sense bio-acoustic vibrations. A gesture-sensing system may be operated by the wearable device, a gesture-controlled device, or another device to recognize the gestures based on the sensor data using a trained support-vector machine as a classifier.