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Open AccessArticle

Investigation of Electrical Stability and Sensitivity of Electric Double Layer Gated Field-Effect Transistors (FETs) for miRNA Detection

1
Institute of Nanoengineering and Microsystems, National Tsing Hua University, Hsinchu 300, Taiwan
2
Department of Power Mechanical Engineering, National Tsing Hua University, Hsinchu 300, Taiwan
*
Author to whom correspondence should be addressed.
Sensors 2019, 19(7), 1484; https://doi.org/10.3390/s19071484
Received: 13 February 2019 / Revised: 14 March 2019 / Accepted: 23 March 2019 / Published: 27 March 2019
(This article belongs to the Special Issue I3S 2018 Selected Papers)
In this research, we developed a miRNA sensor using an electrical double layer (EDL) gated field-effect transistor (FET)-based biosensor with enhanced sensitivity and stability. We conducted an in-depth investigation of the mechanisms that give rise to fluctuations in the electrical signal, affecting the stability and sensitivity of the miRNA sensor. Firstly, surface characteristics were studied by examining the metal electrodes deposited using different metal deposition techniques. The lower surface roughness of the gold electrode improved the electrical current stability. The temperature and viscosity of the sample solution were proven to affect the electrical stability, which was attributed to reducing the effect of Brownian motion. Therefore, by controlling the test conditions, such as temperature and sample viscosity, and the surface characteristics of the metal electrodes, we can enhance the stability of the sensor. Metal electrodes deposited via sputtering and e-beam evaporator yielded the lowest signal fluctuation. When ambient temperature was reduced to 3 °C, the sensor had better noise characteristics compared to room temperature testing. Higher viscosity of samples resulted in lower signal fluctuations. Lastly, surface functionalization was demonstrated to be a critical factor in enhancing the stability and sensitivity. MiRNA sensors with higher surface ratios of immobilized DNA probes performed with higher sensitivity and stability. This study reveals methods to improve the characteristics of EDL FET biosensors to facilitate practical implementation in clinical applications. View Full-Text
Keywords: field-effect transistors (FETs); sensors; stability; miRNA; electric double layer (EDL) field-effect transistors (FETs); sensors; stability; miRNA; electric double layer (EDL)
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Kuo, W.-C.; Sarangadharan, I.; Pulikkathodi, A.K.; Chen, P.-H.; Wang, S.-L.; Wu, C.-R.; Wang, Y.-L. Investigation of Electrical Stability and Sensitivity of Electric Double Layer Gated Field-Effect Transistors (FETs) for miRNA Detection. Sensors 2019, 19, 1484.

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