A vapor cooling condensation system was used to deposit high quality intrinsic ZnO thin films and intrinsic ZnO nanorods as the sensing membrane of extended-gate field-effect-transistor (EGFET) glucose biosensors. The sensing sensitivity of the resulting glucose biosensors operated in the linear range was 13.4 μA mM−1 cm−2. To improve the sensing sensitivity of the ZnO-based glucose biosensors, the photoelectrochemical method was utilized to passivate the sidewall surfaces of the ZnO nanorods. The sensing sensitivity of the ZnO-based glucose biosensors with passivated ZnO nanorods was significantly improved to 20.33 μA mM−1 cm−2 under the same measurement conditions. The experimental results verified that the sensing sensitivity improvement was the result of the mitigation of the Fermi level pinning effect caused by the dangling bonds and the surface states induced on the sidewall surface of the ZnO nanorods.
To utilize the piezoelectric property of ZnO nanorods, the ZnO nanorod array was grown on the AlGaN/GaN field-effect-transistor as the pressure sensors. The drain-source current of the ZnO nanorod-structured-AlGaN/GaN FET pressure sensors can be effectively modulated by the induced gate voltage caused from the piezoelectric phenomenon of ZnO nanorods under different pressures. The pressure sensors revealed the linearly response current under the pressure from 19.6 mN/mm2 to 490 mN/mm2. The ratio of the response current achieved 2.67% under the pressure of 490 mN/mm2. The induced piezoelectric potential under different pressure was also calculated and obtained in this work.
In this work, an easy and low cost aqueous solution growth method was used to directly grow various-length ZnO nanorod arrays as the extended-gate sensing electrode of the pH sensors. To reduce the Fermi level pinning effect caused by the surface states and the dangling bonds resided on the sidewall surface of the ZnO nanorod arrays, the passivation was carried out using the photoelectrochemical (PEC) method. To investigate the function of the length of the ZnO nanorods, various-length ZnO nanorods were grown in the pH sensors. The experimental results revealed that the sensitivity of the pH sensors with passivated ZnO nanorod arrays was better than that of the pH sensors with unpassivated ZnO nanorods, when pH value varied from 4 to 12. Furthermore, the pH sensors with passivated ZnO nanorod arrays exhibited more linear sensing response range for the length of ZnO nanorods from 0.25 to 1.25 m compared to the pH sensors with unpassivated ZnO nanorod arrays.
J282) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 132.174.254.159 Downloaded on 2015-05-25 to IP Journal of The Electrochemical Society, 158 (9) J282-J285 (2011) J283 ) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 132.174.254.159 Downloaded on 2015-05-25 to IP
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