Sensitivity and quality factor improvement of photonic crystal sensors by geometrical optimization of waveguides and micro-ring resonators combination

Abstract In this work, the process of designing and simulating optical sensors based on photonic crystal (PC) micro-ring resonators (MRRs) has been investigated. According to the PC type, different waveguides and resonators can be designed, and various topologies can be proposed from their combination, for optical sensor applications. Here, the investigated MRR is of the symmetrical micro-hexagonal ring resonator (MHRR) type. Different arrays of MHRR arrangement have been designed to investigate their effects on the output spectrum. The results of the design and simulation of different topologies have been analyzed and compared with other numerical researches. Considering all the necessary aspects of PC optical sensors, a detailed and comprehensive algorithm has been presented for designing these devices and choosing the optimal structure. In a more complementary process, the effects of reflector rods have been investigated, which indicates the existence of similarity and compatibility in the design between the distance of reflector rods and the length of MHRRs to obtain the optimal structure. Finally, the effect of different values of lattice constant and radius of dielectric rods on FWHM, transmission (TR) and resonant wavelength is studied, and the most optimal mode is presented. In order to measure the performance of the proposed optimal sensor, its application for gas detection has been analyzed. TR, FWHM, quality factor (QF), sensitivity (S) and figure of merit (FOM) of the proposed sensor were equal to 96%, 0.31 nm, 2636, 6451 nm/RIU and 2960 RIU−1 respectively. An examination of results from similar research indicates a rational and effective approach for generating diverse topologies, aiming to attain the most optimal configuration for optical sensors employing MRRs. Furthermore, employing a systematic design process based on established principles and the proposed algorithm helps prevent arbitrary parameter variations, facilitating the attainment of desired outcomes in a more streamlined and efficient manner. Given the comprehensive nature of this research, it presents a viable solution for designing optical devices based on MRRs for use in optical integrated circuits (OICs) applications

In-vehicle wireless driver breath alcohol detection system using a microheater integrated gas sensor based on Sn-doped CuO nanostructures

Abstract In this paper, we have developed an in-vehicle wireless driver breath alcohol detection (IDBAD) system based on Sn-doped CuO nanostructures. When the proposed system detects the ethanol trace in the driver`s exhaled breath, it can alarm and then prevents the car to be started and also sends the location of the car to the mobile phone. The sensor used in this system is a two-sided micro-heater integrated resistive ethanol gas sensor fabricated based on Sn-doped CuO nanostructures. Pristine and Sn-doped CuO nanostructures were synthesized as the sensing materials. The micro-heater is calibrated to provide the desired temperature by applying voltage. The results showed that by Sn-doping in CuO nanostructures, the sensor performance can be significantly improved. The proposed gas sensor has a fast response, good repeatability along with good selectivity that makes it suitable for being used in practical applications such as the proposed system

Fabrication of Graphene Oxide-Based Resistive Switching Memory by the Spray Pyrolysis Technique for Neuromorphic Computing

Recently, resistive switching memory (RRAM) has been attractive for implementing electronic synapses in neural networks and high-density memory technology. In this paper, we report a different technique for fabricating an Al/GO/ITO RRAM device with multilevel storage capability. In this work, graphene oxide (GO) thin films have been deposited by the spray pyrolysis technique (SPT) using GO powder synthesized by chemical oxidation of graphite flakes via the modified Hummers method. The fabricated RRAM shows good switching performance between On and Off states with the best memory window of 20 and presents reliable retention characteristics of 104 s and 50 reproducible write–read DC cycles without degradation. The multilevel feature points out five stable multiresistant states obtained with the variation of the compliance current (Icc) and reset voltage amplitude. The successful long-term potentiation and depression with 10 ms pulse operation allows to apply this memory in neuromorphic computing applications in addition to 11 gradual conductance levels achieved by continuous set and reset cycles. A comparison of the efficiency of SPT with that of the typical spin coating method showed a notable (87%) yield achieved by SPT. The combination of the multilevel capacity of fabricated RRAMs with SPT was exploited to suggest that GO-based RRAMs have the potential to be used as multibit GO memristors and electronic synapse devices for emerging neuromorphic chips. In addition, this work paves the way for the fabrication of solution-based, low-cost, simple and large-scale GO memristors for future electronics

Resistive-Based Gas Sensors Using Quantum Dots: A Review

Quantum dots (QDs) are used progressively in sensing areas because of their special electrical properties due to their extremely small size. This paper discusses the gas sensing features of QD-based resistive sensors. Different types of pristine, doped, composite, and noble metal decorated QDs are discussed. In particular, the review focus primarily on the sensing mechanisms suggested for these gas sensors. QDs show a high sensing performance at generally low temperatures owing to their extremely small sizes, making them promising materials for the realization of reliable and high-output gas-sensing devices