Smartphone-based simultaneous pH and nitrite colorimetric determination for paper microfluidic devices

In this work, an Android application for measurement of nitrite concentration and pH determination in combination with a low-cost paper-based microfluidic device is presented. The application uses seven sensing areas, containing the corresponding immobilized reagents, to produce selective color changes when a sample solution is placed in the sampling area. Under controlled conditions of light, using the flash of the smartphone as a light source, the image captured with the built-in camera is processed using a customized algorithm for multidetection of the colored sensing areas. The developed imageprocessing allows reducing the influence of the light source and the positioning of the microfluidic device in the picture. Then, the H (hue) and S (saturation) coordinates of the HSV color space are extracted and related to pH and nitrite concentration, respectively. A complete characterization of the sensing elements has been carried out as well as a full description of the image analysis for detection. The results show good use of a mobile phone as an analytical instrument. For the pH, the resolution obtained is 0.04 units of pH, 0.09 of accuracy, and a mean squared error of 0.167. With regard to nitrite, 0.51% at 4.0 mg L−1 of resolution and 0.52 mg L−1 as the limit of detection was achieved

Fully 3D-Printed RFID Tags based on Printable Metallic Filament: Performance Comparison with other Fabrication Techniques

FDM (Fused Deposition Modelling) 3D printing emerged in the last few years as one of the most promising additive manufacturing techniques for fast prototyping. In this work, this technique is used to fabricate UHF (Ultra High Frequency) RFID (Radiofrequency Identification) flexible tag antennas, using a plastic-based conductive filament with copper inclusions, called Electrifi. A comparison with other prototypes with similar shape but fabricated through different and already investigated techniques [1] has been performed in terms of ease of use, processing time, cost, tag sensitivity, radiation pattern, and impedance. More specifically, 3D-printing technology for RFID tag fabrication is compared with inkjet printing, screen printing, wax-based deposition, and cutting plotter. The conductive properties of the antennas realized with the Electrifi filament, as expected, are lower than those of the antennas realized with the other techniques. Nevertheless, a slight degradation in terms of tag performances, is balanced by the extremely high versatility of the fabrication technique. Moreover, the capability to easily fabricate a fully 3D printable antenna, together with the possibility to print complex and not only planar geometries, pave the way to interesting and meaningful future developments. © 2019 IEEE

Consensus of the ambulatory surgery commite section of the Spanish Association of Surgeons on the role of ambulatory surgery in the SARS-CoV-2 pandemic

The current situation of the SARS-CoV-2 pandemic has paralyzed non-urgent and/or oncological surgery in many hospitals in our country with what it means for the health of citizens who are awaiting a surgical procedure. Outpatient Surgery can afford more than 85% of the surgical procedures that are performed in a surgical department and is presented as a feasible and safe alternative at the present time since it does not require admission and decreases clearly the risk of infection. In addition, it is the tool that should be generalized to solve the accumulation of patients on the waiting list that the pandemic is generating, so it seems appropriate that the Ambulatory Surgery section of the Spanish Association of Surgeons present a series of recommendations for the implementation of outpatient surgery in these exceptional circumstances that we have to live. (C) 2021 AEC. Published by Elsevier Espana, S.L.U. All rights reserved

Screen Printed Flexible Radiofrequency Identification Tag for Oxygen Monitoring

In this work, a radiofrequency identification (RFID) tag with an optical indicator for the measurement of gaseous oxygen is described. It consists of an O2 sensing membrane of PtOEP together with a full electronic system for RFID communication, all printed on a flexible substrate. The membrane is excited by an LED at 385 nm wavelength and the intensity of the luminescence generated is registered by means of a digital color detector. The output data corresponding to the red coordinate of the RGB color space is directly related to the concentration of O2, and it is sent to a microcontroller. The RFID tag is designed and implemented by screen printing on a flexible substrate for the wireless transmission of the measurement to a remote reader. It can operate in both active and passive mode, obtaining the power supply from the electromagnetic waves of the RFID reader or from a small battery, respectively. This system has been fully characterized and calibrated including temperature drifts, showing a high-resolution performance that allows measurement of very low values of oxygen content. Therefore this system is perfectly suitable for its use in modified atmosphere packaging where the oxygen concentration is reduced below 2%. As the reading of the O2 concentration inside the envelope is carried out with an external RFID reader using wireless communication, there is no need for perforations for probes or wires, so the packaging remains completely closed. With the presented device, a limit of detection of 40 ppm and a resolution as low as 0.1 ppm of O2 can be reached with a low power consumption of 3.55 mA.Junta de Andalucía (Proyecto de Excelencia P10-TIC-5997 and P10-FQM-5974)Project PYR-2012-12, CEI BioTIC (CEB09-0010 and CEI2013-P-2) from CEI program of MICINNEuropean Regional Development Funds (ERDF