The effect of bending on laser-cut electro-textile inductors and capacitors attached on denim as wearable structures

In this paper we present the design, fabrication and characterization of electro-textile inductor and capacitor patterns on denim fabric as a basis for the development of wearable e-textiles. Planar coil inductors have been harnessed as antenna structures for the development of Near Field Communication (NFC) tags with temperature sensing capability, while interdigitated electrode (IDE) capacitors have been used as humidity sensors for wearable applications. The effect of bending in the electrical performance of such structures was evaluated, showing variations below 5% in both inductance and capacitance values for bending angles in the range of interest, i.e. those fitting to human limbs. In the case of the fabricated NFC tags, a shift in the resonance frequency below 1.7% was found, meaning that the e-textile tag would still be readable by an NFC- enabled smartphone. In respect of the capacitive humidity sensor, we obtained a minimum capacitance variation of 40% for a relative humidity range from 10% to 90%. Measured thermal shift was below 5% in the range from 10 to 40oC. When compared to the 4% variation due to bending, it can be concluded that this capacitive structure can be harnessed as humidity sensor even under bending strain conditions and moderate temperature variations. The development and characterization of such structures on denim fabrics, which is one of the most popular fabrics for everyday clothing, combined with the additional advantage of affordable and easy fabrication methodologies, means a further step towards the next generation of smart e-textile products

QRsens:dual-purpose quick response code with built-in colorimetric sensors

QRsens represents a family of Quick Response (QR) sensing codes for in-situ air analysis with a customized smartphone application to simultaneously read the QR code and the colorimetric sensors. Five colorimetric sensors (temperature, relative humidity (RH), and three gas sensors (CO₂, NH₃ and H₂S)) were designed with the aim of proposing two end-use applications for ambient analysis, i.e., enclosed spaces monitoring, and smart packaging. Both QR code and colorimetric sensing inks were deposited by standard screen printing on white paper. To ensure minimal ambient light dependence of QRsens during the real-time analysis, the smartphone application was programmed for an effective colour correction procedure based on black and white references for three standard illumination temperatures (3000, 4000 and 5000 K). Depending on the type of sensor being analysed, this integration achieved a reduction of ∼71 – 87% of QRsens's dependence on the light temperature. After the illumination colour correction, colorimetric gas sensors exhibited a detection range of 0.7–4.1%, 0.7–7.5 ppm, and 0.13–0.7 ppm for CO2, NH3 and H2S, respectively. In summary, the study presents an affordable built-in multi-sensing platform in the form of QRsens for in-situ monitoring with potential in different types of ambient air analysis applications

Wireless wearable wristband for continuous sweat pH monitoring

Several studies have shown that the determination of pH in sweat, which is one of the most accessible body fluids, can be an indicator of health and wellness, and even be used for potential disease diagnosis. On that basis, we present herein a wearable wristband for continuous and wireless monitoring of sweat pH with potential applications in the field of personal health assessment. The developed wristband consists of two main parts: a microfluidic cloth analytical device (μCAD) to collect continuously the sweat from skin with a color-based pH sensing area; and a readout and processing module with a digital color sensor to obtain the pH of sweat from the color changes in the μCAD. In addition, the readout module includes a low-power Bluetooth interface to transmit the measurements in real-time to a custom-designed smartphone application. To allow continuous operation, an absorbent pad was included in the design to retire and store thsweat from the sensing area through a passive pump path. It was found that the Hue parameter (H) in the HSV color space can be related to the sweat pH and fitted to a Boltzmann equation (R2 = 0.997). The range of use of the wristband device goes from 6 to 8, which includes the pH range of sweat, with a precision at different pH values from 3.6 to 6.0 %. Considering the typical human sweat rate, the absorbent pad allows continuous operation up to more than 1000 minutes

Color Measurements in Blue-Tinted Cups for Virgin-Olive-Oil Tasting

Color measurements have been performed using eighteen virgin-olive-oil tasting cups with ten different commercial virgin olive oils, positioned in a color cabinet with a D65 source. Three geometries (spectroradiometer tilted 0°, 30°, and 60°) were employed, simulating different positions of the taster’s eye. Our main goal was to test whether traditional blue-tinted cups effectively conceal the color of virgin olive oils, as desired in sensorial analyses. None of the cups employed had all their geometrical dimensions within the standardized values, despite being cups used in official sensorial analyses. Measuring a magnitude similar to the spectral transmittance, we found substantial differences among the glasses of the eighteen tasting cups. Comparing color variability for one virgin olive oil in different tasting cups, and one tasting cup with different virgin olive oils, we discovered that: (1) variability was higher in the case of one virgin olive oil in different cups; (2) in both cases the variability increased with the tilt of the spectroradiometer; (3) even when the variability was lowest (i.e., 0° measurements for two oils in the same cup), the average color difference was above typical visual thresholds in simultaneous comparison experiments. In the most usual case of a successive comparison between two oils in the same tasting cup, it is expected that in most cases tasters will perceive color differences between the oils when their eyes are tilted 60° with respect to the horizontal, but not when they observe the cup in the horizontal direction. In summary, blue-tinted olive-oil-tasting cups reduce, but do not completely conceal, oil color. The use of opaque tasting cups with black walls is suggested.Research Project P06-AGR-01744, Consejería de Innovación, Ciencia y Empresa, Junta de Andalucía (Spain), with European Regional Development Fund (ERDF) support.Peer reviewe

Toxicity of silver and gold-silver alloy nanoparticles in marine and freshwater microalgae

Trabajo presentado en el XVII Seminario Ibérico de Química Marina (evento que une al IV Congreso de Ciencias del Mar, IV Simposio Internacional de Ciencias del Mar y al Encuentro de la Oceanografía Física), celebrado en Las Palmas de Gran Canaria del 11 al 13 de junio de 2014.The development of the nanotechnology has promoted the use of metal nanoparticles (MNPs) and nano-materials (NMs) for a wide range of areas and applications. In the daily life are being extensively used inhousehold products (cosmetics or sunscreens) or in industrial uses (paints, catalysts, coatings, packagingmaterial, electronics, etc.). Since the NMs are in continuous growth, the emerging market is estimates toexceed one trillion dollars by 2015 (DEFRA, 2007).Nanoparticles (NPs) occurrence in the environment might cause adverse effects over the ecosystemshealth and consequently, these effects need to be assessed. Ecotoxicological methods should be de-veloped in order to assess the NPs risks. Their effect over life is largely influenced not only by theirinteraction with the surrounded aquatic media but also by the physico-chemical properties of the NPs.In aquatic media, the NPs mostly tend to be dissolved in their ions or to suffer different aggregations,which largely determines its toxicity. The extent of this aggregation mainly is dependent on the surfacecharge, particles morphology (shape and size), pH and the ionic strength of the medium. In seawater theincreasing salinity, and therefore ionic strength, reduces the negativity of electrophoretic mobility of theparticles to encourage aggregation (Batley et al., 2013).Most studies have been conducted with freshwater species such asDaphnia magna(Lovern and Kapler,2006) andPimephales promelas(Zhu et al., 2006). Unfortunately, in spite of the high importance intothe trophic structure of ecosystems, just a few marine species and photosynthetic organisms (Navarro etal., 2008) have been checked in these kind of studies.Traditionally, gold nanoparticles (AuNPs) have been widely considered as non-toxic particles althoughtheir potential toxicity has not been fully assessed, yet. On the opposite, the toxicity of the silver nanopar-ticles (AgNPs) has raised an increasing attention. Some of the most important factors related to thetoxicity of both types of NPs are the oxidative stress and the effect on DNA, lipids and certain metabolicactivities (Lapresta-Fernandez et al., 2012). Therefore, an ecotoxicity study was carried out for some living species in the presence of AgNPs,dissolved silver (Agdis) and silver-gold alloy nanoparticles (AuAgNPs). Interestingly, by modifyingthe NPs composition, the toxicity of the NPs can be fine-tuned. In order to assess the toxicity ofAgNPs and Agdis, a 72 hours exposure testing growth inhibition was performed over two marine di-atoms species (Phaeodactylum tricornutumandCylindrotheca closterium) and two freshwater microal-gae species (Chlamydomonas reinhardtiiandNitzschia palea). Moreover, AuAgNPs toxicity responseswere studied inP. tricornutumandN. palea.The results show AgNPs toxicity (in terms of EC50) is smaller with Agdis for all species tested. HigherEC50 is also observed in marine species.N. paleais the most sensitive species (EC50Agdis = 0.081±0.017μM and EC50AgNP = 0.707±0.198μM); whileC. closteriumis the most resistant species(EC50Agdis = 0.043±1.074μM and EC50AgNP = 2.219±0.159μM). In the case of AuAgNPs, theEC50 values found for the random species studied are 3.286±1.217μM for N. palea and 0.990±0.231μM forP. tricornutum.N

Near-Field Communication Tag for Colorimetric Glutathione Determination with a Paper-Based Microfluidic Device

Here, we propose a microfluidic paper-based analytical device (mu PAD) implemented with a near-field communication (NFC) tag as a portable, simple and fast colorimetric method for glutathione (GSH) determination. The proposed method was based on the fact that Ag+ could oxidize 3,3';,5,5'-tetramethylbenzidine (TMB) into oxidized blue TMB. Thus, the presence of GSH could cause the reduction of oxidized TMB, which resulted in a blue color fading. Based on this finding, we developed a method for the colorimetric determination of GSH using a smartphone. A mu PAD implemented with the NFC tag allowed the harvesting of energy from a smartphone to activate the LED that allows the capture of a photograph of the mu PAD by the smartphone. The integration between electronic interfaces into the hardware of digital image capture served as a means for quantitation. Importantly, this new method shows a low detection limit of 1.0 mu M. Therefore, the most important features of this non-enzymatic method are high sensitivity and a simple, fast, portable and low-cost determination of GSH in just 20 min using a colorimetric signal.BBVA FoundationEuropean Commission European Commission Joint Research Centre H2020-MSCA-IF-2017-794885-SELFSENSpanish Government PID2019-103938RB-I00 PID2020-117344RBI00Junta de Andalucia BFQM-243-UGR18 P18-RT-2961European Commissio