TABLE 2.

Summary of results obtained from four independent biofilms grown without calcium addition

Sample	Scan no.	Vol displaced after 4 raster abrasions (μm3)	Friction forcea (nN)	Frictional energy dissipatedb (pJ)	Cohesive energyc (pJ/μm3)
Biofilm 1	4	1.090	3.49	16.89	15.5
	8	0.156	2.37	22.32	143.1
	12	0.137	2.31	32.53	235.7
	16	0.893	4.85	95.42	106.7
	20	0.106	5.25	129.63	1,222.9
Biofilm 2	4	0.663	5.33	26.31	39.7
	8	0.250	3.54	34.32	137.3
	12	0.075	1.35	17.86	238.1
	16	0.838	3.45	66.85	79.8
	20	0.062	6.44	160.02	2,560.3
Biofilm 3	4	0.981	6.36	31.61	32.2
	8	0.480	4.24	41.55	86.4
	12	0.325	1.69	23.08	71.1
	16	0.506	1.73	31.70	62.6
	20	0.044	3.08	74.16	1,693.1
Biofilm 4	4	0.544	3.57	17.31	31.8
	8	0.631	3.05	29.29	46.4
	12	0.363	3.86	56.40	155.4
	16	0.688	4.39	86.09	125.1
	20	0.062	6.85	170.48	2,727.7

^aThe slope was 0.0012 ± 0.0002 V/nN.

^bFrictional energy dissipated = W_T − W_h. The length of each scan line was 2.5 μm, and the number of scan lines per raster was 256.

^cCohesive energy (ε_coh) = (W_T − W_h)/V.