Adhesion Force Characterization Force characterization for synthetic gecko hair for optimal hair design Goal: Create a system which can accurately measure the adhesive force of the synthtic gecko foot hair material. Approach: Using an automated stage with sub-micron position resolution, we are able to control the movement of a sample accurately. By pressing this sample against a glass slide which is affixed to a load cell, we can measure the deflection and calculate the force which is producing this deflection. The system is integrated with an inverted microscope so that it is possible to view the contact behavior and area. The force data is fed into a controlling PC via a Analog-to-Digital input card so that data can be continuously recorded. The team has written a program to control the stage in realtime and record the data and video. A sample of this data can be seen to the right. Benefits: By testing synthetic samples we will be able to determine the adhesive forces. This will aid in our design process because we will be able to optimize such factors as hair density, material, length, etc. Furthermore, we will be able to characterize the motions which effectively detach the hairs. This will allow us to determine the most efficient and simple motions by which ultra-mobile robots can detach their feet. Videos: Video 1: Contact with flat PDMS sample Video 2: Buckling of 4um diameter PDMS fibers Members: Mike Murphy, Burak Aksak, Eugene Cheung, Chytra Pawashe, Metin Sitti

[CAD image of the Force Characterization System] [Sample data from the force characterization experiments]