handwritten electronics

Junyi Zhao demonstrates using a simple ballpoint pen to write custom LEDs on paper (left). The same pens can be used to draw multicolored designs on aluminum foil (top right) and to create light up sketches (bottom right). (Images courtesy of Wang lab)
Handwritten electronics and devices from a ballpoint pen?
Junyi Zhao demonstrates using a simple ballpoint pen to write custom LEDs on paper (left).