YZ Adhesion Testing 3

Test Setup

• 2-axis YZ stage.
• Control loop at 1kHz embedded on Microchip PIC18F2620?
• Control done using trajectory files with waypoints and linear interpolation
• Sampling force plate at 1kHz.
  • Data filtered at 10 Hz using 3rd order Butterworth filter

Summary of results

mu' is the ratio between maximum preload and maximum adhesion; alpha is the angle relating maximum adhesion to shear under load: tan(alpha) = Fadhesion/Fshear (see K. Autumn et al., Frictional Adhesion paper for explanation).

• See ScanningElectron? (Private web) for SEM pictures of long/short stalks

Experiment #1

Procedure

• Pre-load along 45 degree approach angle to a specified depth in Z (0 to 1000um in 100um increments)
• Pull-off at specified angle (0 to 180 degrees in 15 degree increments; 0 = drag with curvature; 180 = drag against curvature)

Materials

• Sample - Directional Adhesive Pad, "Long"-type, #1A
• Sample - Directional Adhesive Pad, "Short"-type, #2A
• Substrate - Glass

Results for Sample 1A

• Measured maximum forces in Y and Z at pull-off (i.e. Limit Surface)

• Mu Prime as a function of Pre-Load @ best pull-off angle (30 degrees)

• Mu Prime as a function of Pull-Off angle @ best pre-load depth (700um)

Results for Sample 2A

• Measured maximum forces in Y and Z at pull-off (i.e. Limit Surface)

• Mu Prime as a function of Pre-Load @ best pull-off angle (30 degrees)

• Mu Prime as a function of Pull-Off angle @ best pre-load depth (500um)