An Innovative Sensor for Sensitive Determination of Phenobarbital in Real Samples Using CeO₂/CuO/MnO and CeO₂/CuO/NiO Ion-Sensitive Field Effect Transistors

Phenobarbital (PB) is a medication prescribed for insomnia, anxiety, and seizures. PB abuse has dangerous side effects, and the design of sensors with real-time sensing is critical for its detection. Various methods are used to measure PB. The electrochemical methods have many advantages, and the use of nanomaterials has increased their efficiency. However, the classical electrochemical methods have a variety of production standards, making it nearly impossible to mass produce the three-electrode design and integrate it into another system for these intentions. The ion-sensitive field effect transistor (ISFET) was developed to overcome such limitations. In this study, ISFET-based cerium dioxide/copper oxide/manganese oxide (CeO2/CuO/MnO) and CeO2/CuO/nickel oxide (CeO2/CuO/NiO) were evaluated for the IR ability to measure PB for the first time. Based on our results, the limit of detection (LOD) and sensitivity for CeO2/CuO/MnO (CCM) were <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$4.79~\mu $ </tex-math></inline-formula>M and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$58.6~\mu $ </tex-math></inline-formula>A/mM, respectively. In comparison, the LOD and sensitivity of CeO2/CuO/NiO (CCN) were <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$1.18~\mu $ </tex-math></inline-formula>M and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$150.8~\mu $ </tex-math></inline-formula>A/mM, respectively. The better results with the CCN sensing layer were attributed to better catalytic activity, conductivity, and electron transfer ability of nickel oxide (NiO) compared with manganese oxide (MnO). However, both sensors could measure PB in urine and can be used in clinical applications.