Laser-Induced Graphene-Based Electrochemical Sensor for 4-Nitrophenol from Polyimide and Polyethersulfone Precursors

Electrochemical sensors provide an excellent alternative for the in-situ detection of pollutants in water. 4-Nitrophenol is a critical pollutant owing to its acute toxicity and adverse health effects on humans and other living organisms. It is known to have carcinogenic, mutagenic, and teratogenic effects on aquatic life plants and human beings at very low concentrations. In this work, a facile electrochemical sensor for 4-Nitrophenol detection is proposed by laser-induced graphene (LIG) printed on polyethersulfone (PES) and polyimide (PI) films respectively. The laser irradiation of polymeric films results in 3D porous graphene structure formation that increases electron transfer rate as well as the electrochemically active surface area (EASA). This fabrication approach by laser-scribing provides a simple, fast, chemical-free, mask-free, and scalable solution to produce graphene-based electrochemical sensors for 4-Nitrophenol. Cyclic voltammetry is used as the electrochemical technique for the highly sensitive detection of 4-Nitrophenol. PES-based LIG sensors exhibit a higher sensitivity of 3793 µAmM-1cm-2 as compared to that of PI-based LIG sensors with a sensitivity of 3025 µAmM-1cm-2

Study of THz-Plasmon hybridization of a loop Yagi-Uda absorber

Abstract In this article we present a three-dimensional loop Yagi-Uda array for efficient, polarization independent and directional absorption of THz radiation over a narrow frequency range (f0 = 0.657 THz & Q factor = 7.5). Unit cell of the array consists of three vertically stacked gold micro rings separated from each other by 30 µm thick SU-8 layers. The proposed array also exhibits a filtering response in its transmittance spectrum. The characteristics are explained by plasmon hybridization method. The transmission, reflection and absorption spectra of the structure are measured and they show a good agreement with corresponding simulated results