The ability of field effect transistors (FETs) to detect charge variations on the gate may be exploited for realizing chemo- and bio-sensors. In this paper, we focus our attention on a particular kind of field effect device, named organic charge modulated FETs, whose features can be optimized for charge detection in liquid solutions. The results of the measurement of different bio-related effects are shown. In particular, DNA hybridization and pH detection in liquid media are proposed. Finally, preliminary considerations about the applicability of these devices to the detection of the electrical activity of cells are also provided. The device has considerable potential for being employed as a reliable, high sensitivity, low cost technology for sensing signals derived from living systems.