Electrochemical transistor

An electrochemical transistor, comprising:

• an ion diffusion member,
• a gate electrode located on a first surface of said ion diffusion member, and
• a source electrode and a drain electrode located on a second surface of said ion diffusion member that opposes to said first surface with an insulator interposed between said source electrode and said drain electrode, wherein a gate voltage is applied to said gate electrode to diffuse metal ions in said ion diffusion member such that said metal ions are super-saturated on said source electrode and said drain electrode as well as on said insulator near said both electrodes to make electrical connection between said source electrode and said drain electrode by way of a metal precipitated by said supersaturation,
• wherein when a source/drain reference gate voltage lies in a positive first area, electrical connection is made between said source electrode and said drain electrode, and when said source/drain reference gate voltage is then changed over to a positive or zero second area lower than said positive first area, said electrical connection is eliminated by said first area of said source/drain reference gate voltage, and
• wherein when said source/drain reference gate voltage lies in a third area higher than said positive first area, nonvolatile electrical connection occurs.