A new sensing metric is proposed for a field-effect transistor (FET)-based biosensor. As proof of concept, a nanogap-embedded FET is studied to reduce data fluctuations that originate from process variations during FET fabrication and environmental variations stemming from bioexperiments. The new sensing metric utilizes a crucial gate voltage (V G@I sub,max), which induces the maximum substrate current. The new sensing metric shows higher immunity against variations of the nanogap length, compared with the commonly used metric that relies on threshold voltage or drain current. The proposed metric also shows smaller fluctuation, which is caused by environmental variation coming from biotreatment steps. This analysis is verified experimentally and proved by device simulations. For simple analysis, the effect of external charge of the biomolecules is eliminated by using peptide nucleic acid, which is an electrically neutral biomolecule. Thus, by using such biomolecules, the permittivity effect rising from the biomolecules within the nanogap of the gate dielectric is investigated.
Bibliographical noteFunding Information:
Manuscript received October 4, 2011; revised May 21, 2012; accepted July 13, 2012. Date of publication August 15, 2012; date of current version September 18, 2012. This work was supported in part by the National Research and Development Program under Grant 2012-0001131 for the development of biomedical function monitoring biosensors and by the Center for Integrated Smart Sensors and the Basic Science Research Program through the National Research Foundation of Korea funded by the Ministry of Education, Science, and Technology under Grant CISS-2011-0031845 and Grant 2009-008062, respectively. The review of this paper was arranged by Editor A. M. Ionescu.
- Coefficient of variation (CV)
- drain current
- field-effect transistor (FET)-based biosensor
- impact ionization
- label free
- nanogap-embedded FET
- peptide nucleic acid (PNA)
- substrate current
- threshold voltage
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Electrical and Electronic Engineering