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In this study, a cost-effective and highly sensitive cholesterol microsensor, which is consisted of cholesterol oxidase (ChOx), horseradish peroxidase (HRP), and polyaniline (PANI), was developed based on the enzyme-induced conductivity change of PANI with fast response. Hydrogen peroxide is produced via the reaction between cholesterol and ChOx, which was immobilized in a dialysis membrane. The produced hydrogen peroxide can oxidize HRP, which can be reduced by oxidizing PANI, thus resulting in decreased conductivity of the polyaniline thin film. The reduced HRP can be oxidized again by hydrogen peroxide and the cycle of the oxidation/reduction continues until all hydrogen peroxide are reacted, leading to the high sensitivity of the sensor due to the signal contributed from all hydrogen peroxide molecules. Cholesterol was detected near the physiological concentrations ranging from 100 mg/dl to 400 mg/dl with the cholesterol microsensors. The results show linear relation between cholesterol concentration and the conductivity change of the PANI. The microsensor showed no response to cholesterol when the PANI was standalone without cholesterol oxidase immobilized, indicating that the enzymatic reaction is required for cholesterol detection. The simple process of the sensor fabrication allows the sensor to be cost-effective and disposable usage. This electronic cholesterol microsensor is promising for point-of-care health monitoring in cholesterol level with low cost and fast response. [ABSTRACT FROM AUTHOR]

The supplementary zones surrounding an ordinary Fresnel zone plate (FZP) are utilized to improve the optical resolution at focus. Based on the Fresnel–Kirchhoff diffraction formula, an optimization model is used to design the supplementary zones-surrounded FZP (SZFZP). We justified this optimization model by comparing the numerical simulations and experimental measurements in the visible light region. As expected, the comparison shows a good fit between the simulation and measurement. Mostly, both results showed that the optical resolution and the focal intensity in the visible light region are improved by applying the optimized SZFZP. Afterwards, this model is used to design the SZFZP for applications in extreme ultraviolet (EUV) light. At this point, we demonstrated the ability to fabricate the optimized SZFZP in the EUV region. In addition, we simulated the focusing properties for the designed SZFZP. Consequently, the numerical results for EUV light focused by the designed SZFZP exhibited better performances in optical resolution and intensity. [ABSTRACT FROM AUTHOR]