electrode spacing in both patterns was kept as constant of 6 mm. The measurements in Figures 29(b-d) were conducted with electrode width of the large/small/large patterns of 8 mm/2 mm/8 mm and 6 mm/2 mm/6 mm, under slow, normal and fast sliding respectively. Similarly, the measurements in Figures 29(e-g) were conducted with electrode width of 8 mm/4 mm/8 mm and 6 mm/4 mm/6 mm. From the results, it can be observed that with larger difference in the electrode width, the variation of the output signal amplitude is more obvious. But if the electrode with small width is too narrow, its generated output peak will have limited amplitude due to the small contact area, which is easily submerged in the large output peaks from the electrodes with large width. Accordingly, electrode widths of 8 mm and 4 mm may be adopted for the electrodes in the L/S coding configuration. 

Based on the above optimisation results, a sensor was fabricated with large electrode width of 8 mm, small electrode width of 4 mm, and electrode spacing of 6 mm. In the ideal case, the electrodes with larger width should produce higher output peaks due to the larger contact area during sliding. However, due to the relatively large size of the human finger of ~15 mm and the small electrode spacing of 6 mm, the finger may cover two adjacent electrodes simultaneously and cause the overlapping of generated output peaks, as shown in Figure 35. The negative peak of the former signal may overlap with the positive peak of the later signal, leading to amplitude reduction of the second signal. Thus amplitude of the output peaks may not come out as expected (namely, large amplitude from large electrode and small amplitude from small electrode). 

I n order to accurately recognise the electrode patterns, a forward/ backward sliding strategy is proposed together with a signal interpretation table, as illustrated in Figure 35 and Table S5. 

Due to the relatively large size of human finger of ~15 mm and the small electrode spacing of 6 mm, there are situations where finger are covering two electrodes (e.g., finger sliding out of the first electrode and sliding in the second electrode) at the same time. This causes the overlapping of negative component 

