El porqué no se realizó el 'Wii Vitality Sensor' de Nintendo - El Vortex
Nintendo Patent Shows Wii Vitality Sensor Game Example - Siliconera
All Is Forgiven - Penny Arcade
IGN on Twitter: "From a PC joystick to a network system for the NES in 1988 to the never released Wii Vitality Sensor, here are (almost) all of Nintendo's accessories and peripherals