We exploit a solid-liquid dual-gate organic transistor structure, where the threshold voltage of the liquid-gated conduction channel is controlled by an additional gate that is separated from the channel by a metal oxide gate dielectric. With this design the threshold voltage of the “sensing channel” can be linearly tuned in a voltage window exceeding 0.4 V. In general, the capability of tuning the optimal sensing bias will not only improve the device performance but also broaden the material selection for display devices.