No abstract

Point of care (PoC) devices are highly demanding to control current pandemic, originated from severe acute respiratory syndrome Coronavirus 2 (SARS-CoV-2). Though nucleic acid-based methods such as RT-PCR are widely available, they require sample preparation and long processing time. PoC diagnostic devices provide relatively faster and stable results. However they require further investigation to provide high accuracy and be adaptable for the new variants. In this study, laser-scribed graphene (LSG) sensors are coupled with gold nanoparticles (AuNPs) as stable promising biosensing platforms. Angiotensin Converting Enzyme 2 (ACE2), an enzymatic receptor, is chosen to be the biorecognition unit due to its high binding affinity towards spike proteins as a key-lock model. The sensor was integrated to a homemade and portable potentistat device, wirelessly connected to a smartphone having a customized application for easy operation. LODs of 5.14 and 2.09 ng/mL was achieved for S1 and S2 protein in the linear range of 1.0–200 ng/mL, respectively. Clinical study has been conducted with nasopharyngeal swabs from 63 patients having alpha (B.1.1.7), beta (B.1.351), delta (B.1.617.2) variants, patients without mutation and negative patients. A machine learning model was developed with accuracy of 99.37% for the identification of the SARS-Cov-2 variants under 1 min. With the increasing need for rapid and improved disease diagnosis and monitoring, the PoC platform proved its potential for real time monitoring by providing accurate and fast variant identification without any expertise and pre sample preparation, which is exactly what societies need in this time of pandemic.

His research interests include synthesis of functional materials, printed electronics, and radio frequency devices.

Gas sensor technology is widely utilized in various areas ranging from home security, environment and air pollution, to industrial production. It also hold great promise in non-invasive exhaled breath detection and an essential device in future internet of things. The past decade has witnessed giant advance in both fundamental research and industrial development of gas sensors, yet current efforts are being explored to achieve better selectivity, higher sensitivity and lower power consumption. The sensing layer in gas sensors have attracted dominant attention in the past research. In addition to the conventional metal oxide semiconductors, emerging nanocomposites and graphene-like two-dimensional materials also have drawn considerable research interest. This inspires us to organize this comprehensive 2020 gas sensing materials roadmap to discuss the current status, state-of-the-art progress, and present and future challenges in various materials that is potentially useful for gas sensors.

No abstract

No abstract

No abstract

This paper presents several new active RC circuits employing the Operational Transresistance Amplifier (OTRA) as the active element. Applications of the OTRA in realizing a differential voltage amplifier, a differential integrator, continuous time filters and a quadrature oscillator are presented. The effectiveness of the proposed circuits is demonstrated using PSpice simulations. ÜbersichtDie Arbeit stellt einige neue aktive RC-Schaltungen vor, in denen Operationsverstärker mit stromgesteuerten Spannungsquellen (OTRA) als aktive Elemente zum Ensatz kommen. Anwendungen des OTRA als differentieller Spannungsverstärker, differentieller Integrator, biquadratische Filer und Quadratur-Oszillator werden gezeigt. Der Nutzen der vorgeschlagenen Schaltungen wird mit PSpice-Simulationen nachgewiesen.Für die Dokumentation Operationsverstärker als stromgesteuerte Spannungsquellen / aktive Schaltungen Frequenz 54(2000) 7-8 Brought to you by | University of Arizona Authenticated Download Date | 5/27/15 2:33 AM