This research work presents, for the first time, a screen-printed electrode (SPE) made on a PCB board with silver tracks (Ag) and a three electrode configuration (AgxO-working, AgxO-counter and Ag/AgxO-reference electrodes), following the same approach as printed-circuit boards (PCBs). This low cost and disposable device was tested for screening a cancer biomarker in point-of-care. The selected biomarker was carcinogenic embryonic antigen (CEA) protein, routinely used to follow-up the progression of specific cancer diseases.
The biosensor was constructed by assembling a plastic antibody on the Ag-working electrode area, acting as the biorecognition element of the device. The protein molecules that were entrapped on the polymer and positioned at the outer surface of the polypyrrole (PPy) film were removed by protease action. The imprinting effect was tested by preparing non-imprinted (NPPy) material, including only PPy as biorecognition element. Infrared and Raman studies confirmed the surface modification of these electrodes. The ability of the sensing material to rebind CEA was measured by several electrochemical techniques: cyclic voltammetry (CV), impedance spectroscopy (EIS) and square wave voltammetry (SWV). The linear response ranged from 0.05 to 1.25 pg/mL against logarithm concentration.
Overall, producing screen-printed electrodes by means of conventional PCB technology showed promising features, mostly regarding cost and prompt availability. The plastic antibody-based biosensor also seems to be a promising tool for screening CEA in point-of-care, with low response time, low cost, good sensitivity and high stability.
Power market deregulation imposed the separation of several activities such as power production, transmission and distribution, with the consequent separation of these activities costs. This article presents and compares methods that allow determining how much and who must pay for the use of the electrical transmission network. This issue is analysed, under the point of view of several transmission system users: generators, loads and transactions being analysed. The advantages and disadvantages of each method, from the point of view of the considered users are discussed. The embedded methods are used as the base of costs calculation, specifically the methods Postage-Stamp and MW-mile and some of its variants. This study is illustrated using a simple nine-bus electrical network that being used by R&D groups for several projects concerning power markets.
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