pH Sensor Based on LDMOS Transistor With Floating Gate and Ring Structure

Lateral double-diffused metal-oxide semiconductors (LDMOSs) have applications in various devices. In this letter, the characteristics of a proposed sensor application based on an LDMOS incorporating a floating gate are reported. Furthermore, the possible applications of the proposed device are explored. In addition to being applicable to the unmodified complementary metal- oxide-semiconductor process, the layout of our device can be optimized for ion detection purposes. The sensitivity results across a pH range of 1-12 were approximately 9.01, 8.52, 8.73, and 7.81 nA/pH for the polysilicon lengths of 3.5, 4, 5, and 6 μm, respectively. The linearities of the LDMOSs were approximately 0.941, 0.940, 0.949, and 0.950 for the same polysilicon lengths. The results show that the proposed device is pH-responsive and exhibits linearity throughout the pH detection experiment. This proves that the proposed device is suitable for application as an ion sensor.