One Degree of Freedom 7-R Closed Loop Linkage as a Building Block of Nanorobots.

A robotic manipulator is a series of links connected with kinematic pairs designed so that its configuration (three dimensional pose – particularly at the end effector) is controllable. The control is achieved through a series of one degree of freedom revolute or prismatic joints. Nanorobots are linkage mechanisms at nanoscale. These robots offer considerable promise in diverse applications in nanotechnology, biotechnology and medicine. Similar to their macro-scale siblings, a nanorobot must have a controllable kinematic structure to perform tasks. However, at nanometer levels creation of controllable single degree of freedom kinematic pairs are unlikely. Therefore controllability of the nanorobot remains a technological challenge. In this paper, we present a peptide-based linkage composed of protein building-block molecules designed as a one degree-of-freedom closed-loop 7R spatial mechanism. Traditional spatial kinematic notation and formulations are used to solve the loop closure equations implicitly. Two different kinematic branches of this molecular linkage are identified. The designed molecule is fabricated and its motion is observed at distinct configurations using nuclear magnetic resonance (NMR) spectroscopy. These results validate our formulation, and indicate that 7R spatial closed loop linkages are a suitable building block for nanorobots and nanomachines.