I started this project about two years ago, and have played with it off and on. What you see here is the second iteration with a custom manufactured PCB.

By combining a servo motor, some springs, and a laser range sensor, the chopsticks can detect when they are held near a surface or food item and close. They open again, after a brief delay to allow you to eat, when no object nearby is sensed.

Autochopsticks

The original prototype:

Code for this project on github is here