Abstract
We have been developing a new pH measurement device by integrated pH-sensitive field-effect transistor (pH-FET) sensor into microfluidic device made from polydimethylsiloxane (PDMS). The device has many advantages such as small size, short response time, low consumption of sample solution, and internal transparency. In the previous report, we calibrated the device and measured around the neutral pH range then the device showed low measurement error. Though the measurement of pH with wide range eagerly desired, the device has not adapted for acidic or alkalic range yet. In this paper, we investigated the expansion of the linear range on the pH measurement device. The device showed high linearity in the range of pH 1 to 10. The correlation factor of the linear approximation of six standard solutions was 0.9985. The measurement error of these standard solutions was -0.0083±0.085. The device would be applied for many fields soon.
