As shown in Figure 21, a carbohydrate-based elastomer may be fabricated for use as a flexible electrode material. Liquid PDMS was prepared by mixing silicone elastomer base and cross-linker (Sylgard 184, Dow Corning) at a mass ratio of 10: 1. Both starch-based hydrogel and liquid PDMS were degassed in a vacuum chamber to remove gas bubbles in the gel. Then they were mixed together at a volume ratio of 3 :1 to obtain a precursor of carbohydrate- based elastomer. To remove the bubbles in the precursor, the precursor was centrifuged for 10 min at a speed of 3000 rpm. Voltage ratios for electrodes E1-E4 of the sensor 10 were measured at various points on the grid 22. Figure 17 shows (a) 100 tests of voltage ratios of opposite electrodes at lattice points No. 13, No. 15, and No. 25, showing good cent rality (b) Voltage ratios of E3 and El with 25 testing points, and the voltage ratios of E4 and E2 with 25 testing points (c) Comparison between the test location and the actual locat ion (d) The average values and the standard deviation values of the ratios V$_{E}$$_{3}$/ V$_{Ei}$ and V$_{E4}$/ V$_{E2}$ in a sequential order (e) Tests of sensor 10 under varying humidity (f) Tests of sensor 10 under varying force. To generate the results in Figure 3(a), measurement for each virtual "pixel" or cell (1-25) was repeated 100 times to calculate the average value as the standard contact point in the square area. For each point, 100 groups of the peak output voltages were obtained in advance. Because of the restriction imposed by the grid 22, the finger contact points with the silicone rubber substrate are mainly concentrated in the centre area of each pixel. With 100 tests, we obtained stable outputs, and the voltage ratios also show notable aggregation. Then the ratios of Ri = /$_{E3}$/ /$_{Ei}$ and R2 = /$_{E4}$/ /$_{E2}$ of each group were calculated, as shown in Figure 17(b). The average values of the calculated R and R2 for each touch point are listed in Table S2 and Table S3, respectively. Table S2. Voltage ratios ca lculated ( Ri ). x = 0.7 x = 1.9 x = 3.1 x = 4.3 x = 5.5