A low-cost and open-hardware portable 3-electrode sleep monitoring device.

To continue sleep research activities during the lockdown resulting from the COVID-19 pandemic, experiments that were previously conducted in laboratories were shifted to the homes of volunteers. Furthermore, for extensive data collection, it is necessary to use a large number of portable devices. Hence, to achieve these objectives, we developed a low-cost and open-source portable monitor (PM) device capable of acquiring electroencephalographic (EEG) signals using the popular ESP32 microcontroller. The device operates based on instrumentation amplifiers. It also has a connectivity microcontroller with Wi-Fi and Bluetooth that can be used to stream EEG signals. This portable single-channel 3-electrode EEG device allowed us to record short naps and score different sleep stages, such as wakefulness, non rapid eye movement sleep (NREM), stage 1 (S1), stage 2 (S2), stage 3 (S3) and stage 4 (S4). We validated the device by comparing the obtained signals to those generated by a research-grade counterpart. The results showed a high level of accurate similarity between both devices, demonstrating the feasibility of using this approach for extensive and low-cost data collection of EEG sleep recordings.

Rapid sequential determination of the explosives 2,4,6-trinitrotoluene and cyclotrimethylenetrinitramine in forensic samples employing a graphite sheet sensor and cyclic square-wave stripping voltammetry.

The development of a portable analytical procedure is described for rapid sequential detection and quantification of the explosives 2,4,6-trinitrotoluene (TNT) and cyclotrimethylenetrinitramine (RDX) in forensic samples using a graphite sheet (GS). A single GS platform works as a collector of explosive residues and detector after its assembly into a 3D-printed cell. The detection strategy is based on cyclic square-wave stripping voltammetry. The cathodic scan from + 0.1 to -1.0 V with accumulation at 0.0 V enables the TNT detection (three reduction peaks), and the anodic scan from + 0.2 to + 1.55 V with accumulation at -0.9 V provides the RDX detection (two oxidation processes). Low detection limit values (0.1 µmol L-1 for TNT and 2.4 µmol L-1 for RDX) and wide linear ranges (from 1 to 150 µmol L-1 for TNT and from 20 to 300 µmol L-1 for RDX) were obtained. The sensor did not respond to pentaerythritol tetranitrate (PETN), which was evaluated as a potential interferent, because plastic explosives contain mixtures of TNT, RDX, and PETN. The GS electrode was also evaluated as a collector of TNT and RDX residues spread on different surfaces to simulate forensic scenarios. After swiping over different surfaces (metal, granite, wood, cloths, hands, money bills, and cellphone), the GS electrode was assembled in the 3D-printed cell ready to measure both explosives by the proposed method. In all cases, the presence of TNT and RDX was confirmed, attesting the reliability of the proposed device to act as collector and sensor.

Simple-to-use and portable device for free chlorine determination based on microwave-assisted synthesized carbon dots and smartphone images.

A new portable and simple 3D printed device was designed for free chlorine determination in water samples. The analytical method was based on the quenching caused by free chlorine on the fluorescence emission of the carbon dots (CD) synthesized from citric acid and urea. The fluorescence was captured through the camera of a smartphone, which was coupled to the 3D printed device, and the images were processed using the RGB system by the ImageJ 1.51q software. The proposed method was selective and precise (RSD% 4.6, for n = 6), and the trueness of the results was evaluated by comparing the results obtained with those recovered by the spectrophotometric method 4500-Cl G (standard method), with good agreement between them. Moreover, the remarkable correlation between the CD signal and the free chlorine concentration resulted in a determination with low detection limits (limit of detection of 6 µg L-1 and limit of quantification of 20 µg L-1). Therefore, the new method and the related portable device could be considered a fast, economical and reliable alternative for the on-site determination of free chlorine in water samples.

Multivariate classification for the direct determination of cup profile in coffee blends via handheld near-infrared spectroscopy.

Professional cupping is a reliable methodology for the coffee industry and its professionals. However, it faces barriers for its implementation on an industrial scale. To date, no study has determined a coffee cup profile using a handheld near-infrared (NIR) spectrometer. Therefore, the aim of this study was to evaluate directly cup profiles in roasted and ground coffee blends via handheld NIR spectroscopy combined with partial least squares with discriminant analysis (PLS-DA), in an industrial case study. The sensitivity and specificity of the model obtained ranged from 91 to 100%, 84-100%, and 73-95% in the training, prediction, and internal cross-validation sets, respectively. These results are therefore promising for the industrial reality and the methodology could assist coffee professionals in their decisions during cup evaluation in further tests. The proposed method is viable for the direct determination of cup profile at industrial scale since it is portable, fast, simple, robust, and less expensive compared to the benchtops equipment.

Ineficacy of portable device AccutrendⓇ Plus in equine internal medicine / Ineficácia do aparelho portátil AccutrendⓇ Plus na clínica médica de equinos

Four blood components (glucose, lactate, triglycerides and cholesterol) were determined and compared using a portable device (Accutrend® Plus, ROCHE) and laboratory methods. Blood samples from 20 horses were analyzed (11 geldings and 9 mares, from various breeds with age and weight varying between 8 ± 5 years and 327.60 ± 64.02 Kg, respectively. After complete clinical examination, blood was withdrawn through venipunction of the external jugular and these samples were analyzed using a portable device and compared to laboratory results. Statistical analyses were used to compare both methodologies. The results showed that glucose data were not different with a weak Pearson's correlation and no agreement according to Bland-Altman method. The results obtained for lactate according to both methods were also not in agreement. Triglycerides and cholesterol data could not be compared due to the fact that reference values for resting horses lie below the reading range of the portable device. The present study showed that the use of AccutrendⓇPlus to determine glucose, lactate, triglycerides, and cholesterol levels, is not adequate in equine internal medicine.

Comparou-se nesse estudo a determinação de quatro constituintes sanguíneos (glicose, lactato, triglicérides e colesterol), entre um aparelho portátil e métodos laboratoriais convencionais. Foram analisados o sangue de 20 equinos (11 machos e 9 fêmeas), de diversas raças com idades variando entre 8 ± 5 anos e peso corpóreo de 327,60 ± 64,02 Kg. Após exame clínico completo de cada animal realizou-se punção da veia jugular externa para coleta de amostra sanguínea, de maneira que a mesma amostra, foi utilizada para determinação no aparelho portátil e no laboratório. Na comparação entre as metodologias, em relação a glicose, não foi notada diferença entre as médias (teste T de Student), a correlação de Pearson revelou-se fraca e não houve concordância segundo o método de Bland-Altman. Para o lactato também não se observou concordância entre os dois métodos. Quanto aos triglicérides e colesterol foi possível apenas a análise descritiva dos resultados, devido as concentrações dos padrões fisiológicos de equinos em repouso, se apresentarem inferiores ao intervalo de leitura do aparelho portátil. Este trabalho demonstrou que o uso do referido aparelho para determinação de glicose, lactato, triglicerides e colesterol não é adequado na clínica médica equina.