(a) (b) 0 0.5 1 1.5 2 2.5 3 3.5 4 0 50 100 150 200 250 300 350 400 450 500 Vertical height, (mm) Lateral position, (mm) (c) 0 0.5 1 1.5 2 2.5 3 3.5 4 0 50 100 150 200 250 300 350 400 450 500 Vertical height, (mm) Lateral position, (mm) (d) Figure 4: (a) Interferogram of an unactuated, 500 µm long CBA on the test sample (b) Interferogram of an actuated and released, 500µm long CBA on the test sample (c) Height profile of beam 5 shown in image a (d) Height profile of beam 5 shown in image b an actuated and released, 500 µm long cantilever beam shown in Fig. 3d indicates that the smooth in-plane surfaces on the control sample exhibit a crack length (s) of 96 ±5 µm. Figure 4a shows the interferogram of an unactuated, 500 µm long CBA on the test sample. Again, as evident from the height profile shown in Fig. 4c, all the cantilever beams shown in Fig. 4a are free standing before actuation. The interferogram shown in Fig. 4b indicates that most of the 500 µm long cantilever beams on the test sample do not stick to the substrate on actuation. The height profile shown in Fig. 4d further substantiates that the height profile of an actuated, 500 µm long cantilever beam on the test sample is the same as that of an unactuated cantilever beam shown in Fig. 4c. Since the 500 µm long cantilever beams actuated on the test sample do not stick at all, they could not be used to determine the apparent adhesion between in-plane textured surfaces. However, the 1000 µm long cantilever beams actuated on the test sample do exhibit S-shaped height profiles similar to that exhibited by the 500 µm long cantilever beams actuated on the control sample. A crack length of 475±30µmis determined using the 1000µm long CBAs on the test sample. Also, the local adhesion between the in-plane textured surfaces of the test sample is less uniform than that between the in-plane untextured surfaces of the control sample. Table 1 lists the crack lengths observed along with the corresponding calculated apparent work of adhesion between in-plane surfaces on the control and the test samples. The textured in-plane surfaces of the test sample exhibit a significantly reduced apparent work of adhesion as compared to that exhibited by the untextured in-plane surfaces of the control sample. The factor of 300 reduction in the apparent work of adhesion corelates well with the increased roughness exhibited by the textured in-plane surfaces of the test sample as compared to the untextured in-plane surfaces of the control sample. The increased roughness increases the average seperation distance between contacting 185
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