Abstract
Field-effect transistors (FETs) are attractive biosensor platforms for rapid and accurate detection of various analytes through surface immobilization of specific bio-receptors. Since it is difficult to maintain the electrical stability of semiconductors of sensing channel under physiological conditions for long periods, passivation by a stable metal oxide dielectric layer, such as Al2O3 or HfO2, is currently used as a common method to prevent damage. However, protecting the sensing channel by passivation has the disadvantage that the distance between the target and the conductive channel increases, and the sensing signal will be degraded by Debye shielding. Even though many efforts use semiconductor materials directly as channels for biosensors, the electrical stability of semiconductors in the physiological environments has rarely been studied. In this work, an In2O3 nanolines FET device with high robustness in artificial physiological solution of phosphate buffered saline (PBS) was fabricated and used as a platform for biosensors without employing passivation on the sensing channel. The FET device demonstrated reproducibility with an average threshold voltage (VTH) of 5.235 V and a standard deviation (SD) of 0.382 V. We tested the robustness of the In2O3 nanolines FET device in PBS solution and found that the device had a long-term electrical stability in PBS with more than 9 days’ exposure. Finally, we demonstrated its applicability as a biosensor platform by testing the biosensing performance towards miR-21 targets after immobilizing the phosphonic acid terminated DNA probes. Since the surface immobilization of multiple bioreceptors is feasible, we demonstrate that the robust In2O3 FET device can be an excellent biosensor platform for biosensors.
Highlights
Images (Figure 2b), the two ends of the In2 O3 nanolines were in contact with the Ti/Pt electrodes as the source and drain, respectively, while the Si substrate was in contact with the back gated electrode
Current modulation when changing the gate voltage was observed from the output curves of the In2 O3 nanolines Field-effect transistors (FETs) device (Figure 2d)
We found it retained high robustness when kept in phosphate buffered saline (PBS) solution for more than
Summary
Most semiconductor materials of sensing channels cannot be maintained under physiological conditions for long periods of time [10,11]. To solve this problem, surface passivation using a stable metal oxide-based dielectric layer, Micromachines 2021, 12, 642. Robust semiconductor materials for sensing channels that can tolerate long-term use in PBS solution are highly desired. FET-based metal oxide biosensors requires that more stable materials are available for use as the sensing channels. An In2 O3 nanolines FET device with high robustness in artificial physiological solution of PBS was fabricated and used as a platform for biosensors without passivation on the sensing channel.
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