Porous silicon (PS) can be described as a network of silicon nanocrystals with a high specific surface. In particular, the high surface reactivity makes PS a very suitable material for the development of such devices as biosensors. In the present work, devices with a metal/PS/semiconductor/metal structure have been fabricated to be used as electrical biosensors. From current-voltage (I-V) measurements in two different configurations (longitudinal and transversal), it is observed a strong variation of the electrical response as a function of the presence/absence and concentration of biomolecules on the surface of PS. Moreover, by using the above mentioned sensing structures and after biofunctionalization of the surface of PS with aminosilanes and Escherichia Coli antibodies, a relationship between the surface concentration of E. Coli fragments and current variations induced in the I-V curves has been found.