According to Official Guinness Records,
In October 2006, scientists at the University of California, USA, demonstrated a robotic hand only 1mm wide. Using silicon fingers and molecular balloons for joints, the hand could be made to flex and grasp objects by inflating or deflating the balloon joints.
Inventors Yen-Wen Lu and CJ Kim took the human hand as a model and developed the robotic hand to perform similarly complex manipulations at the sub-millimetre scale. With delicate grasp, the hand can be used for a range of complex biological applications that could include complex human micro-surgery.
For a complete list of 2006 records, please visit 2006 Guinness Records in United States.