A double-gate (DG) fin field effect transistor (FinFET) is discussed as new label-free ion and biological sensor. Simulations as function of channel doping, geometrical dimensions, operation point and materials investigated the device response to an external potential difference which provides a body threshold voltage modulation. The simulation results presented in this work clearly state the key features for an ultrasensitive FET based sensor: an enhancement low doped and partially gated transistor operating in weak-moderate inversion regime. The optimized sensitivity, obtained when the width of the fin is equal to the gate height (W-NW similar to h(g)), reaches a value of 85% for an extraction current, I-d, of 0.1 mu A. These results pave the way for the fabrication process of an innovative CMOS compatible sensing system. (C) 2011 Elsevier B.V. All rights reserved.