Organic-based transducer for low-cost charge detection in aqueous media

In this paper we describe a new application for organic field-effect transistors (OFETs) as sensing devices for charge detection in aqueous media. The detection principle is based on the field-enhanced conduction that occurs in organic semiconductors in a similar way as in the crystalline inorganic ones. The electrochemical potential developed at the solution/dielectric interface is responsible for the charge-sensitivity. To prove the principle, we have fabricated and modified an OFET to achieve proton sensitivity. The device concept, testing procedure and the pH response are presented.