Feasibility of conductive embroidered threads for I2C sensors in microcontroller-based wearable electronics

In recent years, the importance of flexible and textile electronics in the field of wearable devices has continuously increased, as they are expected to replace conventional wires that exhibit limited resistance to the mechanical stress occurring in on-body applications. Wearable health devices (WHDs) can provide physiological information about various body parts and employ distributed sensor networks. Among the sensors typically integrated within WHDs, those based on the I2C communication protocol are very common and exploit signals transmitted at frequencies up to hundreds of kilohertz. Therefore, robust communication is required to guarantee a proper transmission of the signal at those frequencies. In this context, we have realized embroidered conductive threads exhibiting a lower resistance, appositely designed to replace conventional wires in a microcontroller-based wearable device employing I2C sensors. A commercial conductive thread (silver coated polyamide) was used to embroider the conductive lines on to cotton fabric. Preliminary measurements were performed to characterize the response of these materials to signals typically operated within the I2C communication protocol at different path lengths. Resistive measurements have also been performed to stimulate different environmental conditions, that is, temperature, the effect of sweating, and repeated washing cycles, also apply mechanical stress, i.e. twisting, with promising results that validate our conductive paths for digital signal communication

HENO-MAC : Hybrid Energy Harvesting-based Energy Neutral Operation MAC Protocol for Delay-Sensitive IoT Applications

The Internet of Things (IoT) technology uses small and cost-effective sensors for various applications, such as Industrial IoT. However, these sensor nodes are powered by fixed-size batteries, which creates a trade-off between network performance and long-term sustainability. Moreover, some applications require the network to provide a certain level of service, such as a lower delay for critical data, while ensuring the operational reliability of sensor nodes. To address this energy challenge, external energy harvesting sources, such as solar and wind, offer promising and eco-friendly solutions. However, the available energy from a single energy source is insufficient to meet these requirements. This drives the utilization of a hybrid energy harvesting approach, such as the integration of solar and wind energy harvesters, to increase the amount of harvested energy. Nevertheless, to fully utilize the available energy, which is dynamic in nature, the sensor node must adapt its operation to ensure sustainable operation and enhanced network performance. Therefore, this paper proposes a hybrid energy harvesting-based energy neutral operation (ENO) medium access control (MAC) protocol, called HENO-MAC, that allows the receiver node to harvest energy from the solar-wind harvesters and adapt its duty cycle accordingly. The performance of the proposed HENO-MAC was evaluated using the latest realistic solar and wind data for two consecutive days in GreenCastalia. The simulation results demonstrate that the duty cycle mechanism of HENO-MAC effectively utilizes the harvested energy to achieve ENO and uses the available energy resources efficiently to reduce the packet delay for all packets and the highest priority packet by up to 28.5% and 27.3%, respectively, when compared with other existing MAC protocols.Peer reviewe

Assessment of structural and optical properties of self-assembled photonic structures

The great potential of self-assembled colloidal structures in several technological areas of modern photonics derives from the low cost and relative simplicity with which they are fabricated. The optical properties of this kind of medium are not only determined by the response of its isolated constituents but also by their spatial arrangement. When polystyrene spheres self-assemble in a periodic fashion, the spatially ordered variation of the dielectric function gives rise to photonic bands and thus the colloidal structure becomes a photonic crystal [1,2]. In this study, colloidal thin films were prepared by the spin-coating [3] and vertical deposition method [4]. By varying the spinning velocity, acceleration and duration of rotation, we obtained different number of colloidal crystal layers. Also, we have prepared opals (multilayer films) with the vertical deposition technique and compared the obtained structures with those obtained by the spin-coating method. In both cases, the thin films were fabricated by depositing colloidal dispersions of 300 nm polystyrene spheres onto microscope glass slide substrates. The morphology of samples was studied by atomic force microscopy, while their optical properties were investigated by spectroscopic ellipsometry and UV-VIS-IR spectrophotometry. An appropriate model has been developed for the determination of the optical properties of the colloidal films by ellipsometry. In order to validate the model applied, the parameters obtained have been compared with those determined by means of transmittance measurements. From transmittance measurements, in the case of monolayer films, diffraction peak in the visible range was observed. On the other side, in the case of opal has been verified the presence of a photonic band gap which should be attributed to Bragg diffraction [5].V International School and Conference on Photonics and COST actions: MP1204, BM1205 and MP1205 and the Second international workshop "Control of light and matter waves propagation and localization in photonic lattices" : PHOTONICA2015 : book of abstracts; August 24-28, 2015; Belgrad

HEADSPACE VOLATILES OF CHAEROPHYLLUM AUREUM L.

Differences in the headspace volatile profiles (HS) of fresh and air-dried fruits, stems and aerial parts of Chaerophyllum aureum L. (Apiaceae) were studied here for the first time using HS-GC-MS (head space – gas chromatography – mass spectrometry). This was done in order to probe to which level HS volatiles of different plant organs were susceptible to air drying. The most dominant headspace volatiles of all samples were monoterpene hydrocarbons. Sabinene was the major volatile of the fresh aerial parts, air-dried fruits, fresh and air-dried stems, representing 47.8%, 31.4%, 67.7% and 73.0% of the total volatiles, respectively. The most abundant headspace volatiles of the fresh fruits were terpinolene (45.3%), γ-terpinene (13.1%) and β-pinene (10.2%). The air-dried aerial parts were characterized by a high amount of limonene (69.0%). The results of HS-GC-MS were subjected to multivariate statistical analysis in order to get a better insight into the similarities/dissimilarities existing between the investigated samples. According to the results of multivariate analysis, the drying process significantly influenced HS volatiles. ISPARLJIVI SASTOJCI BILJNE VRSTE CHAEROPHYLLUM AUREUM L.U ovom radu su, po prvi put, ispitane razlike u headspace profilima (HS) svežih i na vazduhu sušenih plodova, stabljika i nadzemnih delova biljne vrste Chaerophyllum aureum L (Apiaceae) pomoću metode HS-GC-MS (headspace – gasna hromatografija – masena spektrometrija). Na osnovu ovih rezultata moglo bi se utvrditi do koliko intenzivnih promena u HS profilima različitih delova biljke može doći usled sušenja biljnog materijala. U svim uzorcima su dominantni headspace isparljivi sastojci bili monoterpeni. Utvrđeno je da je sabinen bio glavni isparljivi sastojak svežeg nadzemnog dela (47,8%), suvog ploda (31,4%), svežeg (67,7%) i suvog stabla (73,0%). Kao glavni isparljivi sastojci svežeg ploda nađeni su terpinolen (45,3%), γ-terpinen (13,1%) i β-pinen (10,2%), dok je suvi nadzemni deo bio okarakterisan značajno većom zastupljenošću limonena (69,0%). Rezultati HS-GC-MS analize su podvrgnuti multivarijantnoj statističkoj analizi kako bi se dobio bolji uvid u sličnosti/razlike među razmatranim uzorcima. Na osnovu rezultata multivarijantne analize sledi da sušenje u velikoj meri utiče na HS profil. HIGHLIGHTSHeadspace (HS) profiles (percentage compositions) of different parts of Chaerophyllum aureum L. were subjected to multivariate statistical analysis.In all samples, fresh and dry, the most dominant headspace volatiles were monoterpene hydrocarbons.Sabinene was the most abundant volatile of the fresh aerial parts, air-dried fruits, fresh and air-dried stems.The main headspace volatile compound of the fresh fruits was terpinolene while limonene was the major volatile of the air-dried aerial parts

A fully-printed electrochemical platform for assisted colorimetric detection of phosphate in saliva: Greenness and whiteness quantification by the AGREE and RGB tools

Herein, we report the environmental impact quantification of a newly developed fully printed electrochemical device to assist a colorimetric detection of phosphate in saliva. The evaluation of the analytical procedure was per formed according to the principles of Green Analytical Chemistry and White Analytical Chemistry. The standard method for phosphate detection relies on a reaction between phosphate and molybdate in presence of antimony potassium tartrate and ascorbic acid, using strong acid conditions and high volumes of reagents (100–500 mL). To deliver an eco-friendly method, we have combined a screen-printed electrode with a liquid electrolyte battery and inkjet-printed conductive paths to develop a fully printed device on a flexible polymer substrate avoiding the use of ascorbic acid and using a small amount of reagents. The printed sensor was first developed and optimized for phosphate detection in saliva, allowing for a detection limit equal to 26 μM and satisfactory repeatability (relative standard deviation value of 7.5%). Finally, the AGREE and the RGB assessment tools were applied for a quantitative evaluation of the proposed sensor and reference method, in agreement with the Green Analytical and White Analytical principles. The results demonstrated the lower environmental impact of the proposed sensor, as well as the suitability of this novel approach for phosphate detection in saliv

Održiva rešenja u analitičkoj hemiji: Kombinacija instrumentalnih tehnika i ekološki prihvatljivih prirodnih indikatora za klasičnu volumetriju

Dimethyl fumarate (DMF) serves as the active ingredient in medications designed to treat relapsing forms of multiple sclerosis, yet there is a notable absence of specific monographs for this compound in available pharmacopeia’s. Nevertheless, various instrumental chromatographic techniques are employed to determine the concentration of DMF across diverse matrices. This study endeavours to highlight the viability of merging structural instrumental analytical methods with a simple classical volumetric approach utilizing a cost-effective, non- toxic, and natural indicator - the ethanol extract of Curcuma longa powder. The primary aim is to accurately determine DMF assay in commercial samples without utilizing certified reference materials (CRM).The poster presentation of this conference paper was held during the 6th Student Section of the 31st International Conference on Ecological Truth and Environmental Research (EcoTER '24), which took place in Sokobanja, Serbia, from June 18th to 21st, 2024. The presentation was given by the first author, Aleksa Vizi

Impedance analysis of milk quality using functionalized polyamide textile-based sensor

Present paper demonstrates design and characterization of a textile based microfluidic chip sensor for the detection of milk adulteration through measuring the real part of the impedance and impedance phase angle. Polyamide (PA) based textile fabric was chemically functionalized with polyaniline and titanium dioxide nanoparticles (PANI/TiO2) nanocomposite and embedded in the microfluidic chip. Prototyping of microfluidic chip was performed by xurography and hot lamination using polyvinyl chloride foils. Morphological and chemical properties of fabricated textile-based PA-PANI/TiO2 chip sensor were evaluated by scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). Quality of milk was accessed with fabricated textile sensor using cow and goat milk samples. The electrochemical impedance spectroscopy (EIS) was applied to detect the change in resistance and phase angle of pure and diluted milk. The developed PA-PANI/TiO2 chip sensor acted as a variable resistor that was able to identify adulterations and spoilage of the milk samples with sensitivity of 0.06 degrees of phase angle variation per % of water dilution. Our work promises that application of textile electronics could be efficiently exploited for food safety, point-of-care and environment monitoring applications

Role of Graphene Oxide in Bacterial Cellulose−Gelatin Hydrogels for Wound Dressing Applications

Biopolymer-based hydrogels have several advantages, including robust mechanical, high biocompatibility, and excellent properties. These hydrogels can be ideal wound dressing materials and advantageous to repair and regenerate skin wounds. In this work, we have reported fabricated of composite hydrogels from gelatin and graphene oxide-functionalized-bacterial cellulose (synthesized by hydrothermal method) (GO-f-BC) and crosslinked with tetraethyl orthosilicate (TEOS). The hydrogels were characterized using Fourier transform infrared spectroscopy, scanning electron microscopy, atomic force microscopy, and water contact angle analyses to explore functional groups and their interactions, surface morphology, and wetting behavior, respectively. The swelling, biodegradation, and water retention were tested to respond to biofluid. Maximum swelling was exhibited by samle with maximum amount of GO (GBG-4) in all media (aqueous = 1902.83%, PBS = 1546.63%, and electrolyte = 1367.32%). The hemolysis of all hydrogel samples is less than 0.5%, and the blood coagulation time decreased as the hydrogel concentration increased. The composite hydrogels were found to be hemocompatible as they have less than 0.5% hemolysis for all hydrogel samples under in vitro standard conditions. These hydrogels performed unusual antimicrobial activities against Gram (positive and negative) bacterial strains. The cell viability and proliferation were increased with an increased GO amount, and maximum values were found for GBG-4 against fibroblast (3T3) cell lines. The mature and well-adhered cell morphology of 3T3 cells was found against all hydrogel samples. Hence, based on these results findings, these hydrogels would be potential wound dressing skin materials for wound healing applications.We are grateful to the European Union's Horizon to support the research project. This project has received funding from the European Union's Horizon 2020 research and innovation program under grant agreement no. 951747 and acknowledge the NPRP award [NPRP 12S -0310-190276] from the Qatar National Research Fund (a member of The Qatar Foundation). The statements made herein are solely the responsibility of the authors.Scopu

Non-destructive characterisation and classification of ceramic artefacts using pEDXRF and statistical pattern recognition

Background: Portable energy dispersive X-ray fluorescence (pEDXRF) spectrometry analysis was applied for the characterisation of archaeological ceramic findings from three Neolithic sites in Serbia. Two dimension reduction techniques, principal component analysis (PCA) and scattering matrices-based dimension reduction were used to examine the possible classification of those findings, and to extract the most discriminant features. Results: A decision-making procedure is proposed, whose goal is to classify unknown ceramic findings based on their elemental compositions derived by pEDXRF spectrometry. As a major part of decision-making procedure, the possibilities of two dimension reduction methods were tested. Scattering matrices-based dimension reduction was found to be the more efficient method for the purpose. Linear classifiers designed based on the desired output allowed for 7 of 8 unknown samples from the test set to be correctly classified. Conclusions: Based on the results, the conclusion is that despite the constraints typical of the applied analytical technique, the elemental composition can be considered as viable information in provenience studies. With a fully-developed procedure, ceramic artefacts can be classified based on their elemental composition and well-known provenance