A modular passive-to-active exoskeleton system utilizes motor unit modules, an electromagnetic-clutch power transmission system, and biometric control. The passive exoskeleton has a stamina-increasing chairless chair function and optional use of magnetic ball-and-socket joints and knee torsion springs. To convert the exoskeleton system into an active robotic wearable device, modular attachments allow for motor units to be securely connected to the exoskeletal frame. An exoskeleton system may contain a knee motor unit that has a transmission system with an electromagnetic clutch that enables a passive mode, active mode, and/or hybrid mode. The motor units are controlled using wireless biometric motion sensors that measure limb joint angle and muscle activity. These motor units also communicate via wireless transmission with a central processing unit of the exoskeleton. This central processing unit serves as a gateway for user feedback from an Internet-of-Things (IoT) device, such as a smartphone, tablet, computer, etc.

Presented are wearable sensor systems for monitoring user movement, methods for making/using such systems, exoskeletons employing such systems, and wireless-enabled wearable sensor devices for performing biometric measurements. A sensor system for monitoring movement of a user includes a wearable sensor device that is communicatively connectable to a sensor linking node. The sensor linking node wirelessly receives sensor data from the wearable sensor device and wirelessly communicates the received sensor data to a remote computing node. The wearable sensor device includes an expandable device body, such as an elastic compression sleeve or an adjustable strap, that is worn on an appendage of the user. The device body includes a mounting interface, such as mating hook-and-loop fastener pads, that removably mounts thereon a biometric sensor core (BSC) unit. The BSC unit contains a microcontroller assembly that is integral with a microcontroller device, a biometric sensor array, and a wireless communication device.