Si nano-pillars for measuring traction force exerted by filopodia

This paper describes a Si nano-pillars array for measuring traction forces of one singular filopodium (100-300 nm in diameter). We fabricated the Si nano-pillar which was 110 nm in diameter and 1.5 μm in length. Fibroblasts were cultured on the Si nano-pillar array. The filopodium of fibroblast adhered to pillar and dragged it. We calculated the traction force from the deflection of the pillar. When spring constants of Si nano-pillars were 1.7 N/m, 4.1 N/m and 6.6 N/m, averaged traction forces were 580 nN, 1 μN and 2.3 μN, respectively. The cells exerted the large forces with an increase in the stiffness of the pillar. We confirmed that the Si nano-pillar array was able to be used for measuring the traction forces of filopodium.