on the substrate forming the fluidic channels in the desired electrode grid pattern 3904. Then Ecoflex™ 00-30 solution was cast on top and cured at room temperature. Next, Ecoflex 3908 with fluidic channels 3904 was peeled off from the substrate, and then liquid metal 3910 was filled into the fluidic channels using a syringe. Last, another Ecoflex layer was cast on top and cured for encapsulation. 

Characterization of the interface 3300\ The output voltage of the interface 3300 was measured by DSO-X3034A oscilloscope (Agilent) with a high impedance probe of 100 ΜΩ . The output current and charge were measured by Keithley 6514 Electrometer. Programmable Arduino UNO was adopted as the microcontroller unit for signal recognition and command generation. 

As shown in Figure 36, the 0/1-coding interface 1200 shows excellent robustness and reliability in diverse ambient conditions and usage scenarios, such as different humidity, different sliding force, and different sliding speed, etc. The sole constraint is that the sliding speed should be maintained relatively constant during the sliding, whether in a slow, normal or fast manner, due to the detection mechanism of the peak positions in the time domain. Therefore, the variation tolerance of sliding speed for practical usage was investigated. 

There are eight electrode patterns corresponding to the eight directions. Including the beginning and ending reference electrodes 1212a and 1212d, there are 4 classes of generated signals in terms of the number of peaks, i.e., 2 peaks (000), 3 peaks (001, 010, 100), 4 peaks (110, 101, Oi l), and 5 peaks (111). I n the case of 2 peaks and 5 peaks, there is only one possibility for each case, thus 000 and 111 can be easily recognised based on the number of the generated peaks, irrespective of the variation in sliding speed. 

I n the case of 3 peaks, the ideal signal (100) with constant speed is shown in Figure 36(a), with peaks 3600 and 3602 representing the reference peaks, peak 3604 representing the real coding peak, and dashed peak 3606 representing the virtual coding peak generated from the corresponding electrodes. In the schematic, d is the distance between two adjacent electrodes, vl is the average 

