Supporting Beam Length Resonance Frequency (µm) fR ±std.dev. (KHz) 200 13.50 ±0.01 250 9.15±0.01 300 8.34±0.01 350 6.14±0.01 400 4.72±0.01 450 3.92±0.01 500 3.64±0.01 Table 2: Resonance frequencies of resonators with different folded suspension beam lengths. Figure 7: Plot exhibiting the fitting of Eq. 4 to the values reported in Table 2. The slope of the fitted line is the experimentally obtained value of Efor the structural film on chip B. in this paper. To determine the apparent work of adhesion between sidewall surfaces, two SBA’s are actuated on both chip A and chip B in laboratory air at room temperature and a RH of 13%. Apparent work of adhesion between sidewall surfaces on both chip A and chip B as reported in Table 3 is less than that between the corresponding in-plane surfaces. This substantiates the role of roughness in reducing adhesion, since the sidewall surfaces (rms roughness is 6.52 nm) on both the chips have a rougher topography than the corresponding in-plane surfaces (rms roughness is 0.097nm). Chip Apparent In-plane Work of Adhesion Apparent Sidewall Work of Adhesion Wip ±std.dev. (mJ/m2) Ws ±std.dev. (mJ/m2) (RH=13%) (RH=13%) A 0.02±0.001 <0.04 B 22.92±2.5 1.065±0.07 Table 3: Adhesion energies between in-plane and sidewall surfaces on chip A and chip B. 5.3 Friction All the experiments to determine the coefficients of static friction (µs) between sidewall surfaces are conducted in laboratory air at room temperature and a RH of 13%. Three SFAT’s and three SFT’s are actuated on both chip A and chip B. As seen in Table 4, for sidewall surfaces on both chip A and chip B, the static friction coefficients determined using both the SFAT and SFT are in good agreement. However, Ashurst et. al. reported static friction coeffcients of 0.07±0.005 and 1.1±0.1 for OTS coated surfaces and surfaces with only native oxide on them respectively [6]. The 93
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