INVESTIGATINGTHE ROLE OF ORIENTATIONANGLE ON GECKO SETAEADHESION USINGA DUAL-AXISMEMS FORCE SENSOR

A dual-axis piezoresistive MEMS force sensorwas usedtoinvestigate therole oforientation angle on theadhesion ofgecko hairs, called setae. Previous workshowed that thelateral adhesion force ofa single setapulled parallel toa surface ishighly dependant upon the"pitch" angle between theseta's stalk andthesubstrate (1).Thisworkisthefirst toexamine theeffect ofthe"roll" orientation angle of thestalk undersimilar lateral pulls along a substrate. We findthat theadhesion isnearthemaximum value for awideroll angle rangefrom-43° to+43°, andsmoothly drops offtothefrictional force at+85°. Theseangles relate physically totheorientation andspread ofa splayed tuftofspatula-shaped terminations attheendofeachseta.Thesespatulae makeintimate contact withthesubstrate andenhance adhesion above traditional friction forces.