| 摘要 |
PURPOSE:To display hydrogen ion concentration speedily in the form of voltage by forming a niobium oxide thin film on a metallic surface or on a gate insulating film of an electric field effect type transistor FET, and combining this film and a suitable reference electrode with each other. CONSTITUTION:FET has a source l, a drain 2 and a gate 3, and a niobium oxide Nb2O5 thin film is formed on insulation of the gate 3 by means of a plasma CVD method, and a temperature compensating transistor 4 is arranged on the other edge. This FET having ion selectivity and a double junction type silver/silver chloride reference electrode are combined with each other, and it is soaked into various kinds of acid solutions, and a relationship between voltage and hydrogen ion concentration in aqueous solution is found. In this case, voltage between the drain and the source is set to be 2.5V, and electric current of the drain is set to be 100muA. The relationship between the voltage and logarithm of the hydrogen ion concentration shows a linear relationship in a wide range of concentration regardless of kinds of acid. A time until electric potential of the FET is stabilized is considerably short such as within about 5 seconds, so that response speed becomes fast. |
