Because the human heart requires only a small amount of electrical stimulation, researchers were able to shrink their next-generation pacemaker even smaller. The final result is a 1-millimeter-thick device measuring just 1.8 mm wide and 3.5 mm long that is still capable of delivering as much electrical stimulation as a standard pacemaker.

Now, engineers at Northwestern University have developed what could have saved Armstrong’s life: the world’s smallest pacemaker, smaller than a single grain of rice. Unlike traditional pacemakers, this one is injectable, wireless, and dissolves harmlessly into the body at the end of its mission.