ELECTROLYTE TRANSISTORS - IONIC REACTION-DIFFUSION SYSTEMS WITH AMPLIFYING PROPERTIES

The problem of constructing chemoelectric amplifying devices based on acid-base reactions is discussed. It is shown that the construction of a direct analogue of the semiconductor transistor (that is, when the p- and n-doped semiconductors are replaced by ion exchange membranes i n the H+ and OH- forms, respectively) is technically not feasible. The new amplifying device reported here is based exclusively on mobile io ns migrating in a hydrogel arrangement that contains no fixed charges. The polarization curve of an acid-base interface in this medium has a diode characteristic. When two of such ''electrolyte diodes'' are con nected appropriately, a transistor action can be observed: the electri c current flowing in one (reverse biased) diode is affected not only b y the voltage applied there but also by the current flowing through th e other (forward biased) diode. The common emitter current gain of an acid-base-acid transistor studied here was between 4 and 5. The active mode characteristics of this device can be explained by the appearanc e of an acidic tunnel across the alkaline middle section. Although the acid-base-acid transistor is a stable amplifying device, the base-aci d-base transistor is unstable in its active mode and displays complex oscillations. The underlying bistable behavior was also demonstrated w ith this transistor when its acidic feedstream was contaminated with K Cl.