As demonstrated in Figure , an expected linear response was seen for the inkjet printed biosensor for HBsAg. All samples with increasing concentrations of HBsAg showed positive signals. As defined by equation 1, it means conductance was consistently decreased due to the absorption of the HBsAg molecules. The possible mechanism can be the doping effect of the negatively charged HBsAg brought negative gating effect on the p-typed SWCNT-Ab channel, which reduced the conductance of the printed channel. Moreover, the sensors showed a linear response range, i.e., a dynamic range from 1 -10 mM. The sensor response began to plateau after 10 mM as the signal no longer increase eminently like in the dynamic range. Therefore, we believed the sensor surface was saturated with absorbed HBsAg. The absorption was possibly reaching a "pseudo equilibrium" state that the large molecular size of HBsAg hindered the access of free HBsAg in the solution. Thus, the limited accessibility restricted the further absorption and consequent further increase in the signal.