## 3 Results and Discussion
In addition, the sensor having a larger width and shorter length tended to show a higher current, which is reasonable based on [PERSON]'s law. \begin{table}
\begin{tabular}{c c c c c c c c c c c c c} \hline \hline  & 0.1 s\({}^{-1}\) & 200 s\({}^{-1}\) & 0.1 s\({}^{-1}\) & Recovery & 0.1 s\({}^{-1}\) & Recovery & 0.1 s\({}^{-1}\) & Recovery & 0.1 s\({}^{-1}\) & Recovery & 0.1 s\({}^{-1}\) & Recovery \\  & 30 s & 60 s & 75 s & 75 s & 80 s & 80 s & 90 s & 90 s & 110 s & 110 s & 130 s & 130 s \\ \hline L & **1.66** & **0.51** & **0.78** & **47.0\%** & **0.81** & **48.7\%** & **0.85** & **51.1\%** & **0.94** & **56.5\%** & **0.97** & **58.4\%** \\ M & **101.43** & **1.48** & **7.89** & **7.8\%** & **11.33** & **11.2\%** & 23.87 & **23.5\%** & 63.75 & 62.9\% & **91.17** & **89.9\%** \\ H & **501.47** & **2.15** & **90.21** & **18.0\%** & **153.63** & **30.6\%** & **266.42** & **53.1\%** & **376.44** & **75.1\%** & **447.62** & **89.3\%** \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Ag/CB ink viscosity at different shear rates, corresponding to different printing process steps. Figure 2: (a) Steady flow test and (b) PHS test to investigate the rheological behavior of CB/AgNPs paste with different ratios. (c) Microscope images of the printed pattern with different CB concentrations. PHS—peak hold step; CB—carbon black. An advantage of using a printed sensor is its controllable sensitivity. Figure 4a shows the GF of the sensors according to the applied strain. The GF was calculated as follows [12]:  
\[GF=\frac{\Delta R}{R\Delta\varepsilon} \tag{1}\]  
\[\varepsilon=\frac{h}{2r} \tag{2}\]  
\[c=2r\times\sin\left(\frac{1}{2r}\right) \tag{3}\]  
where \(R\) refers to the initial resistance of the sensor under tension-free conditions; \(\varepsilon\) indicates the tensile strain when a stress is applied to the sensor; and \(\Delta R\) indicates the resistance change. The thickness of the sensor, \(h\), and the radius of curvature, \(R\), in the bending process are affected by the applied pressure, whereas the radius of curvature can be calculated through the arc length, l, and chord length, \(c\), in the bending process. It is observed that the strain-dependent responses increase monotonously with the increasing strain. With the application of strain in the range of 0.61% to 1.44% to the sensor, the GF determining the sensor sensitivity varied from 192.77 to 444.6, which is the highest GF among the CB-based printed sensors under a large strain reported so far, to the best of our knowledge [17; 18; 22; 23; 24; 25]. In addition, the sensitivity could be controlled by the dimension effect. Table 2 presents the excellent performance of the CB/AgNP pastes in terms of sensitivity in comparison with the previous results in the literature [26; 27; 28; 29; 30; 31; 32; 33]. The CB/AgNP paste could generate a high GF because the variation of junction resistance was severe under tension pressure, as shown in Figure 4b. The electrons in the conductive film can pass through a percolating lattice of overlapping nanomaterials, and the bending of the sensor can lead to a reduction in the overlapping areas or even a loss of electrical connections, increasing the resistance. Figure 3: (**a**) Images of the screen-printed sensors with different length and width. (**b**) Measured resistance of the screen-printed CB/AgNPs past lines at various dimensions. The mechanical sensitivity and durability of the sensor were investigated to evaluate the properties of the sensor for application in wearable electronics. Figure 5a shows the continuous and uniform increase in the response according to the applied strain with different values, which reveals the calculated linearity as R\({}^{2}\) = 0.9974. Figure 5b displays the high durability of the printed CB/AgNP sensor over 1000 repetitive bending-releasing cycles at the applied strain of 0.275%. All the responses were obtained without any noise during the bending cycles. The specific response is shown as an inset.