Abstract: A hydrogen ion sensing device of the present invention includes: a reference electrode; a sensing portion which senses hydrogen ions by contacting an ion aqueous solution; and a plurality of ring-like lateral bipolar junction transistors, each including a lateral collector, an emitter, a vertical collector and a floating gate connected to the reference electrode, with the emitter surrounded by the floating gate and the lateral collector, wherein the plurality of ring-like lateral bipolar junction transistors are formed on a common substrate and are connected in parallel.

Abstract: A hydrogen ion sensing device includes: a reference electrode; a sensing portion which senses hydrogen ions by contacting an ion aqueous solution; and a plurality of ring-like lateral bipolar junction transistors, each including a lateral collector, an emitter, a vertical collector and a floating gate connected to the reference electrode, with the emitter surrounded by the floating gate and the lateral collector, wherein the plurality of ring-like lateral bipolar junction transistors are formed on a common substrate and are connected in parallel. With this configuration, an operation point can be adjusted by the bases current with the emitter voltage fixed. In addition, polarities of values of X and Y axes are positive in comparison with a p-channel MOSFET driven with the common collector setting and the device can be operated in a linear region (an active mode) in comparison with ISFET operating in a saturation region.