Graphene Sensor Arrays for Rapid and Accurate Detection of Pancreatic Cancer Exosomes in Patients' Blood Plasma Samples

Biosensors based on graphene field effect transistors (GFETs) have the potential to enable the development of point-of-care diagnostic tools for early stage disease detection. However, issues with reproducibility and manufacturing yields of graphene sensors, but also with Debye screening and unwanted detection of nonspecific species, have prevented the wider clinical use of graphene technology. Here, we demonstrate that our wafer-scalable GFETs array platform enables meaningful clinical results. As a case study of high clinical relevance, we demonstrate an accurate and robust portable GFET array biosensor platform for the detection of pancreatic ductal adenocarcinoma (PDAC) in patients' plasma through specific exosomes (GPC-1 expression) within 45 min. In order to facilitate reproducible detection in blood plasma, we optimized the analytical performance of GFET biosensors via the application of an internal control channel and the development of an optimized test protocol. Based on samples from 18 PDAC patients and 8 healthy controls, the GFET biosensor arrays could accurately discriminate between the two groups while being able to detect early cancer stages including stages 1 and 2. Furthermore, we confirmed the higher expression of GPC-1 and found that the concentration in PDAC plasma was on average more than 1 order of magnitude higher than in healthy samples. We found that these characteristics of GPC-1 cancerous exosomes are responsible for an increase in the number of target exosomes on the surface of graphene, leading to an improved signal response of the GFET biosensors. This GFET biosensor platform holds great promise for the development of an accurate tool for the rapid diagnosis of pancreatic cancer.

Towards a Highly Efficient ZnO Based Nanogenerator

A nanogenerator (NG) is an energy harvester device that converts mechanical energy into electrical energy on a small scale by relying on physical changes. Piezoelectric semiconductor materials play a key role in producing high output power in piezoelectric nanogenerator. Low cost, reliability, deformation, and electrical and thermal properties are the main criteria for an excellent device. Typically, there are several main types of piezoelectric materials, zinc oxide (ZnO) nanorods, barium titanate (BaTiO₃) and lead zirconate titanate (PZT). Among those candidate, ZnO nanorods have shown high performance features due to their unique characteristics, such as having a wide-bandgap semiconductor energy of 3.3 eV and the ability to produce more ordered and uniform structures. In addition, ZnO nanorods have generated considerable output power, mainly due to their elastic nanostructure, mechanical stability and appropriate bandgap. Apart from that, doping the ZnO nanorods and adding doping impurities into the bulk ZnO nanorods are shown to have an influence on device performance. Based on findings, Ni-doped ZnO nanorods are found to have higher output power and surface area compared to other doped. This paper discusses several techniques for the synthesis growth of ZnO nanorods. Findings show that the hydrothermal method is the most commonly used technique due to its low cost and straightforward process. This paper reveals that the growth of ZnO nanorods using the hydrothermal method has achieved a high power density of 9 µWcm^-2.

Compatibility of Al-doped ZnO electron transport layer with various HTLs and absorbers in perovskite solar cells

Perovskite solar cells (PSCs) have shown a significant improvement in cell performance in photovoltaics technology. The commonly used light absorbing material of halide-based perovskite in PSCs has produced high efficiency cells with low cost and a simple fabrication process. However, it contains the harmful substance of Pb, which affects the environment, and the cell still suffers from instability in the long run. Therefore, this work presents a theoretical study of the Pb-free absorber layer of CH₃NH₃SnI₃ that is paired for compatibility with various types of hole transport layers (HTLs). Several key parameters of the absorbent layer and HTL have been optimized to produce the highest power conversion efficiency (PCE) using 1D-SCAPS software under AM 1.5 illumination. It was found that the combination of Cu₂O and CH₃NH₃SnI₃ used as the HTL and absorbent layer, respectively, has resulted in great PCE as high as 27.72%. These findings prove that the use of inorganic HTLs and Pb-free perovskite layers is promising for use in PSCs.