Abstract
A fluorine-terminated polycrystalline boron-doped diamond surface is successfully employed as a pH-insensitive SGFET (solution-gate field-effect transistor) for an all-solid-state pH sensor. The fluorinated polycrystalline boron-doped diamond (BDD) channel possesses a pH-insensitivity of less than 3mV/pH compared with a pH-sensitive oxygenated channel. With differential FET (field-effect transistor) sensing, a sensitivity of 27 mv/pH was obtained in the pH range of 2–10; therefore, it demonstrated excellent performance for an all-solid-state pH sensor with a pH-sensitive oxygen-terminated polycrystalline BDD SGFET and a platinum quasi-reference electrode, respectively.
Highlights
After Bergveld [1] first presented an ion-sensitive field-effect transistor (ISFET), various types of ISFET have been presented, i.e., silicon-based ISFETs (Si-ISFETs) with an insulator of tantalum pentaoxide (Ta2 O5 ), with silicon nitride (Si3 N4 ), with aluminum oxide (Al2 O3 ) [2], and with a diamond-like carbon insulator [3]
To decrease/improve the pH sensitivity of boron-doped diamond (BDD) solution-gate field-effect transistors (SGFETs) sensor, the direct-wetted diamond surface, employed as the FET channel, was modified to partially fluorine-terminated BDD and partially oxygen-terminated BDD with the help of the method used in the previous study [8,9,10,11,16]
The specification of the boron-doped diamond film of the BDD SGFET used in this study was
Summary
After Bergveld [1] first presented an ion-sensitive field-effect transistor (ISFET), various types of ISFET have been presented, i.e., silicon-based ISFETs (Si-ISFETs) with an insulator of tantalum pentaoxide (Ta2 O5 ), with silicon nitride (Si3 N4 ), with aluminum oxide (Al2 O3 ) [2], and with a diamond-like carbon insulator [3]. One of the approaches is the on-chip fabrication of an Ag/AgCl gate electrode with a gel filled in a hole [12,13], but the leakage of the gel resulted in the contamination of the sample, or in a limited lifetime Another approach is to use a differential FET sensing technique, which is a combination of an ISFET and a Sensors 2017, 17, 1040; doi:10.3390/s17051040 www.mdpi.com/journal/sensors. Various types of REFETs are reported for differential FET sensing, such as a hydrogel as an insensitive membrane and a parylene layer for an ion blocking material [12]. Another approach is to use specific-ion-sensitive polymeric membranes such as poly (vinyl chloride) (PVC), whose pH sensitivity for protons is lower than for other cations. In order to overcome the abovementioned problems, we first proposed introducing a fluorine-terminated diamond for a pH-insensitive SGFET, which worked in conjunction with an oxygen-terminated diamond channel employing a pH-sensitive SGFET
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
