| 摘要 |
PURPOSE:To enhance a response speed, sensitivity, reversibility, processability, economical efficiency and durability by employing a gel as a receiving part changing in its acoustic characteristic corresponding to a pH change. CONSTITUTION:A phenomenon wherein a gel generating phase transition by a pH change changes in its reflectivity or transmissivity to sonic waves before and after phase transition is utilized. That is, the gel 5 is bonded and formed to the inner wall of a measuring container 1 as shown by a drawing (a) and, when solutions 2 to be measured different in pH flow in the container 1, the gel 5 generates phase transition as shown by drawings (b) - (d) and the concn. and density of the polymer in the gel 5 become high and sonic velocity and the acoustic impedance IM of the gel 5 also increase. Since the IM of the gel 5 and that of the solution are almost equal in the state of the drawing (a), reflectivity is equal to zero but, since the difference between the IM of the gel 5 and that of the solution 2 becomes large as the gel 5 generates phase transition, reflectivity becomes large. When this difference in reflectivity is measured by an ultrasonic detector 3, the pH of the solution 2 can be detected. |
