Over 59 mV pH⁻¹ Sensitivity with Fluorocarbon Thin Film via Fluorine Termination for pH Sensing Using Boron-Doped Diamond Solution-Gate Field-Effect Transistors

pH sensing facilitates many substantial aspects of the society such as chemical laboratory analysis, agriculture, or water and soil qualities. However, existing pH sensors have problems and limitations such as fragility, hysteresis, or slow responding time. In this research, a new method utilizing fluorocarbon thin film via fluorine termination and boron-doped diamond (BDD) solution-gate field-effect transistors (SGFETs) for pH sensing is developed for the first time. The fluorocarbon film device demonstrates a high pH sensitivity of 67.4 and 34.9 mV pH⁻¹ in acid and alkaline pH regions, respectively.