Conventional electronic devices have evolved from the first transistors introduced in the 1940s to integrated circuits and today's modern (CMOS) computer chips fabricated on silicon wafers using photolithography. This chapter reviews such iontronic devices for signal translation and their application in bioelectronics. It begins with a brief description of the ion transport mechanisms that lay the conceptual groundwork for this type of iontronic devices. The chapter presents various iontronic devices aimed at bioelectronic applications. It outlines the future possible developments of iontronics for human-machine interfacing. The physical interface between electronic devices and biological tissues is of particular interest, as this interface bridges the gap between artificial, humanmade technologies and biological "circuits". Ion-conducting diodes and transistors can be used to build circuits for modulation of ion flow, with the possibility of mimicking the dynamic and nonlinear processes occurring in the body.