The Mechanism of Charge Flow and Electric Current in Porous GaN Thin Films during Photo Electrochemical Etching

In this work nano-porous structures of n-GaN was fabricated using simple photoelectrochemical etching techniques. The electrolyte was H2SO4:H2O2 under direct current density of 5 mA/cm2 for 30 min. Scanning electron microscopy (SEM) has been used to studied the morphology, the size, and the shape of the pores of n-GaN nanostructures. The mechanism of charge and current flow in photoelectrochemical etching process was investigated deeply. The electrical and chemical behaviour of the electrolyte-GaN junction has been studied. The energy diagram of an n-GaN and the electrolyte was used to illustrate the charges flow mechanism. A simple model depend on two parallel plate capacitors was used to understand the etching mechanism at the GaN electrolyte interface. This mechanism was confirmed by J-t curve

Plasmonic Biosensors for the Detection of Lung Cancer Biomarkers: A Review

International audienceLung cancer is the most common and deadliest cancer type globally. Its early diagnosis can guarantee a five-year survival rate. Unfortunately, application of the available diagnosis methods such as computed tomography, chest radiograph, magnetic resonance imaging (MRI), ultrasound, low-dose CT scan, bone scans, positron emission tomography (PET), and biopsy is hindered due to one or more problems, such as phenotypic properties of tumours that prevent early detection, invasiveness, expensiveness, and time consumption. Detection of lung cancer biomarkers using a biosensor is reported to solve the problems. Among biosensors, optical biosensors attract greater attention due to being ultra-sensitive, free from electromagnetic interference, capable of wide dynamic range detection, free from the requirement of a reference electrode, free from electrical hazards, highly stable, capable of multiplexing detection, and having the potential for more information content than electrical transducers. Inspired by promising features of plasmonic sensors, including surface plasmon resonance (SPR), localised surface plasmon resonance (LSPR), and surface enhanced Raman scattering (SERS) such as ultra-sensitivity, single particle/molecular level detection capability, multiplexing capability, photostability, real-time measurement, label-free measurement, room temperature operation, naked-eye readability, and the ease of miniaturisation without sophisticated sensor chip fabrication and instrumentation, numerous plasmonic sensors for the detection of lung cancer biomarkers have been investigated. In this review, the principle plasmonic sensor is explained. In addition, novel strategies and modifications adopted for the detection of lung cancer biomarkers such as miRNA, carcinoembryonic antigen (CEA), cytokeratins, and volatile organic compounds (VOCs) using plasmonic sensors are also reported. Furthermore, the challenges and prospects of the plasmonic biosensors for the detection of lung cancer biomarkers are highlighted