An electronic watch may include a housing defining a side wall having a through-hole and a crown assembly including an actuation member. The actuation member may include a crown shaft extending through the through-hole and having an exterior portion defining an input surface and a crown ring coupled to the exterior portion of the crown shaft and electrically isolated from the crown shaft. The crown assembly may further include an optical encoder component attached to the actuation member and defining a group of optical features. The electronic watch may further include an optical detector configured to detect rotation of the crown assembly by detecting motion of the group of optical features and an electrocardiograph sensor comprising a sensing component. The sensing component may be conductively coupled to the actuation member via a conductive path at least partially defined by the crown shaft.