The Application of Electrolyte-solution-gate Diamond FETs (SGFETs) Using Polycrystalline Diamond Surface to Biosensors(<Special Issue>Functional Material, Diamond)

Abstract

The electrolyte-solution-gate diamond field effect transistors (SGFETs) have been fabricated on polycrystalline diamond surface and which are used biosensors worked in electrolyte solution. The hydrogen-terminated diamond surface is sensitive to halogen ions about 30mV/decade, which can be applied to cell biological reaction. The hydrogen-terminated surface channel of the SGFETs was modified into partially aminated and oxygen-terminated (H-A-O-terminated) with irradiation of ultraviolet in an ammonia environment to get pH sensitivity and immobilize enzyme. The pH response of that is obtained about 50mV/pH at pH 2-10. The concentration of substrates (urea or glucose) in the electrolyte solution has been detected by the pH change due to the bio-catalyzed effect of enzyme (urease or glucose oxidase), which is immobilized on the channel of SGFETs. The sensitivity of urea and glucose is approximately 30mV/decade and 20mV/decade respectively.