Determination method of liquid concentration using SH-SAW sensor without reference liquid

A direct methanol fuel cell (DMFC) needs a methanol (MeOH) sensor to keep methanol concentration in optimum range. A shear horizontal surface acoustic wave (SH-SAW) can detect MeOH concentration. In this paper, estimation method of the MeOH concentration is proposed. Normally, the SH-SAW sensor needs a reference liquid at a sample liquid measurement. However, if the SH-SAW sensor is installed in the DMFC, it is difficult to measure the reference liquid. In this paper, the electrical perturbation theory is used. As the electromechanical coupling coefficient is corrected, the theory is good agreement with the experimental results. Using the proposed method, concentration of MeOH solution is estimated and reasonable results are obtained.