By now, most roboticists are familiar with the myriad gecko-type robots that employ Van der Waals forces (created by microscopic synthetic setae) to cling to walls. Less well-known is the work on an electrically-controllable alternative developed by researchers at SRI International (formerly called Stanford Research Institute) called "electroadhesion". Impressively, the electroadhesive can support 0.2 to 1.4 N per square centimeter, requiring a mere 20 micro-Watts per Newton. This means that a square meter of electroadhesive could hold at least 200kg (440 lbs) while only consuming 40 milli-Watts, and could turn on and off at the flick of a switch! Read on for pictures, videos, and discussion.
First, I think it is prudent to examine the competing gecko-style Van der Waals robots that employ microscopic synthetic setae to generate adhesive forces via intermolecular interactions. This technique is employed in nature by real geckos (shown below).
Unfortunately, there is no way to deactivate intermolecular forces; the gecko's feet are always "sticky". Meanwhile, electroadhesives use the electrostatic force generated between high-voltage electrodes on the robot and the surface / substrate, as shown below.
Of course, this material can be employed to support large loads, but more importantly for our purposes, build cool climbing robots!
Many different robot designs have been considered by the SRI researchers.
Very cool stuff! The videos below, though short, show the effect in action on a variety of surfaces (from wood, drywall, cement, glass, and steel).