Wearable electronic sensor was prepared on a light and flexible substrate. The breathing sensor has a broad assumption and great potential for portable devices in wearable technology. In the present work, the application of a flexible thermoplastic polyurethane/multiwalled carbon nanotubes (TPU/MWCNTs) strain sensor was demonstrated. This composite was prepared by a novel technique using a thermoplastic filtering membrane based on electrospinning technology. Aqueous dispersion of MWCNTs was filtered through membrane, dried and then welded directly on a T-shirt and encapsulated by a thin silicone layer. The sensing layer was also equipped by electrodes. A polymer composite sensor is capable of detecting a deformation by changing its electrical resistance. A T-shirt was capable of analyzing a type, frequency and intensity of human breathing. The sensitivity to the applied strain of the sensor was improved by the oxidation of MWCNTs by potassium permanganate (KMnO4) and also by subsequent application of the prestrain.

• Klíčová slova
• CNTs, carbon nanotubes, elastic sensor, monitoring of breathing, polymer composite, strain sensor, wearable electronics,
• Publikační typ
• časopisecké články MeSH

We examine a general wireless sensor network (WSN) model which incorporates a large number of sensors distributed over a large and complex geographical area. The study proposes solutions for a flexible deployment, low cost and high reliability in a wireless sensor network. To achieve these aims, we propose the application of an unmanned aerial vehicle (UAV) as a flying relay to receive and forward signals that employ nonorthogonal multiple access (NOMA) for a high spectral sharing efficiency. To obtain an optimal number of subclusters and optimal UAV positioning, we apply a sensor clustering method based on K-means unsupervised machine learning in combination with the gap statistic method. The study proposes an algorithm to optimize the trajectory of the UAV, i.e., the centroid-to-next-nearest-centroid (CNNC) path. Because a subcluster containing multiple sensors produces cochannel interference which affects the signal decoding performance at the UAV, we propose a diagonal matrix as a phase-shift framework at the UAV to separate and decode the messages received from the sensors. The study examines the outage probability performance of an individual WSN and provides results based on Monte Carlo simulations and analyses. The investigated results verified the benefits of the K-means algorithm in deploying the WSN.

• Klíčová slova
• K-means clustering, centroid-to-next-nearest-centroid (CNNC) trajectory, gap statistic method, optimal UAV positioning, unnamed aerial vehicle (UAV), wireless sensor network (WSN),
• Publikační typ
• časopisecké články MeSH

This paper deals with a development and lab testing of energy harvesting technology for autonomous sensing in railway applications. Moving trains are subjected to high levels of vibrations and rail deformations that could be converted via energy harvesting into useful electricity. Modern maintenance solutions of a rail trackside typically consist of a large number of integrated sensing systems, which greatly benefit from autonomous source of energy. Although the amount of energy provided by conventional energy harvesting devices is usually only around several milliwatts, it is sufficient as a source of electrical power for low power sensing devices. The main aim of this paper is to design and test a kinetic electromagnetic energy harvesting system that could use energy from a passing train to deliver sufficient electrical power for sensing nodes. Measured mechanical vibrations of regional and express trains were used in laboratory testing of the developed energy harvesting device with an integrated resistive load and wireless transmission system, and based on these tests the proposed technology shows a high potential for railway applications.

• Klíčová slova
• electromagnetic transducer, energy harvesting, model, test, train, vibration, wireless sensor,
• Publikační typ
• časopisecké články MeSH

The treatment of some inborn metabolism errors requires cholesterol substitution therapy. Cholesterol plays a vital role in the human body. Therefore, the majority of cholesterol determination techniques are targeted to blood and blood serum. Nevertheless, cholesterol determination in food is important as well. In this paper, cholesterol determination using differential pulse voltammetry (DPV) in dairy products (e.g., milk, clotted cream, yogurt, butter, etc.) is reported with a novel nonenzymatic sensor based on diphosphonic acid of 1,4-diacetylglycoluril (DPADGU) as an electrode surface modifier. Stable anodic response was obtained from cholesterol on the modified carbon-based electrode. The sensor has high stability, sensitivity (20 μA mol L-1 cm-2), and a wide linear range from 1 up to 200 μM. The LOD and LOQ values are 1.5 and 5.1 μM, respectively. The developed methods were successfully applied to the above mentioned dairy products. Graphical abstract ᅟ.

• Klíčová slova
• Cholesterol, Dairy products, Sensor, Smith-Lemli-Opitz syndrome, Voltammetry,
• MeSH
• analýza potravin přístrojové vybavení   MeSH
• biosenzitivní techniky MeSH
• cholesterol analýza   normy   MeSH
• elektrochemické techniky přístrojové vybavení   MeSH
• kalibrace MeSH
• katalýza MeSH
• koncentrace vodíkových iontů MeSH
• referenční standardy MeSH
• spektroskopie infračervená s Fourierovou transformací MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• cholesterol MeSH

This study proposes a new approach to improving laser sensor data collection through optimised sensor settings. Specifically, it examines the influence of laser sensor configurations on laser scanning measurements obtained by using a laser line triangulation sensor for transparent and non-transparent plastics, as well as aluminium alloys. Distance data were acquired with a three-degree-of-freedom positioning device and the laser sensor under both manual and automatic settings. Measurements were performed at the sensor's reference distance and across a wide range of positional configurations. The results of extensive experimental tests highlight optimal sensor configurations for various materials and sensor orientations relative to the scanned surface, including both in-plane and out-of-plane angles, to enhance the reliability and accuracy of distance data collection.

• Klíčová slova
• in plane, laser scanner, out of plane, reliability, sensor placement, triangulation,
• Publikační typ
• časopisecké články MeSH

Solid polymer electrolytes show their potential to partially replace conventional electrolytes in electrochemical devices. The solvent evaporation rate represents one of many options for modifying the electrode-electrolyte interface by affecting the structural and electrical properties of polymer electrolytes used in batteries. This paper evaluates the effect of solvent evaporation during the preparation of solid polymer electrolytes on the overall performance of an amperometric gas sensor. A mixture of the polymer host, solvent and an ionic liquid was thermally treated under different evaporation rates to prepare four polymer electrolytes. A carbon nanotube-based working electrode deposited by spray-coating the polymer electrolyte layer allowed the preparation of the electrode-electrolyte interface with different morphologies, which were then investigated using scanning electron microscopy and Raman spectroscopy. All prepared sensors were exposed to nitrogen dioxide concentration of 0-10 ppm, and the current responses and their fluctuations were analyzed. Electrochemical impedance spectroscopy was used to describe the sensor with an equivalent electric circuit. Experimental results showed that a higher solvent evaporation rate leads to lower sensor sensitivity, affects associated parameters (such as the detection/quantification limit) and increases the limit of the maximum current flowing through the sensor, while the other properties (hysteresis, repeatability, response time, recovery time) change insignificantly.

• Klíčová slova
• gas sensor, ionic liquid, noise spectroscopy, solid polymer electrolyte,
• Publikační typ
• časopisecké články MeSH

This study is focused on the development of water-based ITO nanoparticle dispersions and ink-jet fabrication methodology of an indium tin oxide (ITO) sensor for room temperature operations. Dimensionless correlations of material-tool-process variables were used to map the printing process and several interpretational frameworks were re-examined. A reduction of the problem to the Newtonian fluid approach was applied for the sake of simplicity. The ink properties as well as the properties of the deposited layers were tested for various nanoparticles loading. High-quality films were prepared and annealed at different temperatures. The best performing material composition, process parameters and post-print treatment conditions were used for preparing the testing sensor devices. Printed specimens were exposed to toluene vapours at room temperature. Good sensitivity, fast responses and recoveries were observed in ambient air although the n-type response mechanism to toluene is influenced by moisture in air and baseline drift was observed. Sensing response inversion was observed in an oxygen and moisture-free N₂ atmosphere which is explained by the charge-transfer mechanism between the adsorbent and adsorbate molecules. The sensitivity of the device was slightly better and the response was stable showing no drifts in the protective atmosphere.

• Klíčová slova
• Indium tin oxide, dimensionless number, gas sensor, inkjet ink, material printing, nanoparticle, room temperature,
• Publikační typ
• časopisecké články MeSH

This work presents the design of a polymer-film-based sensor for gas detection. Different types of polyaniline are used as active layers. The advantages of resistive sensors with PANI layers are easy preparation and low production cost. At room temperature, polymer films have a high sensitivity to gas concentrations. The developed sensor works on the idea of electrical resistance shifting with gas concentration. Three different polymerization solutions are employed to synthesize the polyaniline (PANI) active layers (aqueous solution, sulfuric acid solution, and acetic acid solution). Active layers are evaluated in a controlled environment for their ability to detect ammonia, carbon monoxide, nitrogen monoxide, acetone, toluene, and relative humidity in synthetic air. PANI layers polymerized in acetic acid solutions exhibit good sensitivity toward ammonia.

• Klíčová slova
• gas sensor, polyaniline, polymer film,
• Publikační typ
• časopisecké články MeSH

This study introduces an evaluation methodology tailored for bioreactors, with the aim of assessing the stress experienced by algae due to harmful contaminants released from antifouling (AF) paints. We present an online monitoring system equipped with an ultra-sensitive sensor that conducts non-invasive measurements of algal culture's optical density and physiological stage through chlorophyll fluorescence signals. By coupling the ultra-sensitive sensor with flash-induced chlorophyll fluorescence, we examined the dynamic fluorescence changes in the green microalga Chlamydomonas reinhardtii when exposed to biocides. Over a 24-h observation period, increasing concentrations of biocides led to a decrease in photosynthetic activity. Notably, a substantial reduction in the maximum quantum yield of primary photochemistry (FV/FM) was observed within the first hour of exposure. Subsequently, we detected a partial recovery in FV/FM; however, this recovery remained 50% lower than that of the controls. Integrating the advanced submersible sensor with fluorescence decay kinetics offered a comprehensive perspective on the dynamic alterations in algal cells under the exposure to biocides released from antifouling coatings. The analysis of fluorescence relaxation kinetics revealed a significant shortening of the fast and middle phases, along with an increase in the duration of the slow phase, for the coating with the highest levels of biocides. Combining automated culturing and measuring methods, this approach has demonstrated its effectiveness as an ultrasensitive and non-invasive tool for monitoring the physiology of photosynthetic cultures. This is particularly valuable in the context of studying microalgae and their early responses to various environmental conditions, as well as the potential to develop an AF system with minimal harm to the environment.

• Klíčová slova
• Antifouling coatings, Bioreactor, Chlorophyll fluorescence spectroscopy, Microalgae, Toxicity, Ultrasensitive sensor,
• MeSH
• bioreaktory * MeSH
• chemické látky znečišťující vodu analýza   MeSH
• Chlamydomonas reinhardtii * účinky léků   metabolismus   MeSH
• chlorofyl metabolismus   MeSH
• dezinficiencia farmakologie   MeSH
• fluorescence MeSH
• fotosyntéza účinky léků   MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• chemické látky znečišťující vodu MeSH
• chlorofyl MeSH
• dezinficiencia MeSH

Embryo sac formation is a fundamental step in sexual reproduction in plants. However, the key players involved in the development of the female gametophyte remain elusive. We present data indicating that a two-component sensor histidine kinase, CKI1, originally implicated in cytokinin perception, is required for completion of megagametogenesis in Arabidopsis. We isolated a loss-of-function mutation in CKI1 resulting from an insertion of the En-1 transposon into the CKI1 coding sequence. Genetic analysis revealed that the mutant allele, cki1-i, could not be transmitted through the female germ line. Confocal laser scanning microscopy identified a block in megagametogenesis, characterized by the abortion of the central vacuole in mutant embryo sacs, and degradation of the developing female gametophyte after completion of all mitotic divisions. The recovery of two independent stable alleles and one revertant wild-type allele resulting from En-1 excision confirmed unambiguously the causal link between the cki1-i mutation and the abnormal phenotype. In situ localization of CKI1 mRNA and histochemical analysis of stable transformants harboring the uidA gene under the control of CKI1 promoter revealed that expression of CKI1 starts at the very beginning of female gametophyte development, and continues until fertilization. This suggests that the developing embryo sac may remain sensitive to signals recognized by CKI1 throughout megagametogenesis. Furthermore, expression of the paternally transmitted CKI1 was detected early after fertilization. The results indicate a role for a two-component signaling system during female gametophyte development, and provide the first evidence that gametophytic expression of a sensor-like molecule is essential for specific processes during megagametogenesis.

• MeSH
• Arabidopsis embryologie   enzymologie   genetika   MeSH
• molekulární sekvence - údaje MeSH
• proteinkinasy genetika   metabolismus   MeSH
• proteiny huseníčku * MeSH
• sekvence aminokyselin MeSH
• sekvence nukleotidů MeSH
• semena rostlinná embryologie   metabolismus   MeSH
• transpozibilní elementy DNA MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• CKI1 protein, Arabidopsis MeSH Prohlížeč
• proteinkinasy MeSH
• proteiny huseníčku * MeSH
• transpozibilní elementy DNA MeSH