No abstract

The Gram-positive bacterium, Staphylococcus aureus (S. aureus), is a major pathogen responsible for a variety of infectious diseases ranging from cellulitis to more serious conditions such as septic arthritis and septicaemia. Timely treatment with appropriate antibiotic therapy is essential to ensure clinical defervescence and to prevent further complications such as infective endocarditis or organ impairment due to septic shock. To date, initial antibiotic choice is empirical, using a "best guess" of likely organism and sensitivity- an approach adopted due to the lack of rapid identification methods for bacteria. Current culture based methods take up to 5 days to identify the causative bacterial pathogen and its antibiotic sensitivity. This paper provides proof of concept for a biosensor, based on interdigitated electrodes, to detect the presence of S. aureus and ascertain its sensitivity to flucloxacillin rapidly (within 2 hours) in a cost effective manner. The proposed method is label-free and uses non-faradic measurements. This is the first study to successfully employ interdigitated electrodes for the rapid detection of antibiotic resistance. The method described has important potential outcomes of faster definitive antibiotic treatment and more rapid clinical response to treatment.

Graphene is an interesting material with a number of desirable electrical properties. Graphene-based negative differential resistance (NDR) devices hold great potential for enabling the implementation of several elements required in electronic circuits and systems. In this article we propose a novel device structure that exhibits NDR using single layer graphene that is able to be fabricated using standard lithography techniques. Using theoretical simulation, we show that graphene nanoribbon (GNR) junctions exhibit NDR effect if a gap is introduced in the structure in the transport direction of the ribbon. Using standard lithography techniques, we produce a GNR and use electro-migration to create a nanogap by breaking the GNR device. Scanning electron microscopy images show the formation of a tunnel gap. The predicted NDR phenomenon is experimentally verified in the current-voltage characteristic of the device. The linear and non-linear characteristics of the I-V responses before and after breakdown confirm that the NDR effect arises from the tunnel gap.

Abstract:The early detection of colorectal cancer is vital for disease management and patient survival. Fecal hemoglobin detection is a widely-adopted method for screening and early diagnosis. Fecal Immunochemical Test (FIT) is favored over the older generation chemical based Fecal Occult Blood Test (FOBT) as it does not require dietary or drug restrictions, and is specific to human blood from the lower digestive tract. To date, no quantitative FIT platforms are available for use in the point-of-care setting. Here, we report proof of principle data of a novel low cost quantitative fecal immunochemical-based biosensor platform that may be further developed into a point-of-care test in low-resource settings. The label-free prototype has a lower limit of detection (LOD) of 10 µg hemoglobin per gram (Hb/g) of feces, comparable to that of conventional laboratory based quantitative FIT diagnostic systems.

Polymer stabilization by UV light irradiation in nematic liquid crystals is proposed to improve the decay time of coplanar-waveguide-type microwave phase shifters. The effect of polymer concentration on the decay time of polymer-stabilized nematic liquid crystals is confirmed by a dielectric experiment on a liquid-crystal-sandwiched indium–tin-oxide (ITO) glass cell before loading into a coplanar-waveguide-type microwave phase shifter. The decay time, phase shift value, and insertion loss of microwave phase shifters with different polymer concentrations are measured. The decay time of polymer-stabilized nematic liquid crystals in the microwave phase shifter markedly decreases compared with that of pure nematic liquid crystals. It is confirmed that the use of polymer-stabilized nematic liquid crystals is effective to improve the response time of microwave phase shifters.