The objective of this research was to develop highly effective conductive polymer composite (CPC) materials for flexible piezoresistive sensors, utilizing hollow three-dimensional graphitic shells as a highly conductive particulate component. Polystyrene (PS), a cost-effective and robust polymer widely used in various applications such as household appliances, electronics, automotive parts, packaging, and thermal insulation materials, was chosen as the polymer matrix. The hollow spherical three-dimensional graphitic shells (GS) were synthesized through chemical vapor deposition (CVD) with magnesium oxide (MgO) nanoparticles serving as a support, which was removed post-synthesis and employed as the conductive filler. Commercial multi-walled carbon nanotubes (CNTs) were used as a reference one-dimensional graphene material. The main focus of this study was to investigate the impact of the GS on the piezoresistive response of carbon/polymer composite thin films. The distribution and arrangement of GS and CNTs in the polymer matrix were analyzed using techniques such as X-ray diffraction and scanning electron microscopy, while the electrical, thermal, and mechanical properties of the composites were also evaluated. The results revealed that the PS composite films filled with GS exhibited a more pronounced piezoresistive response as compared to the CNT-based composites, despite their lower mechanical and thermal performance.

• Klíčová slova
• 3D graphitic shells, conductive polymer composite, multi-walled carbon nanotubes, piezoresistive sensors,
• Publikační typ
• časopisecké články MeSH

Flexible gas sensor devices are fabricated and optimized by integrating directly, via a single-step vapor-phase deposition method, highly crystalline tungsten oxide nanostructures functionalized with either gold or platinum nanoparticles. Gas tests of these devices show significant improvements with respect to flexible gas sensors based on non-functionalized structures, including greater responses to various volatile organic compounds (ethanol, acetone, methanol and toluene) and better selectivity towards ethanol and methanol, as demonstrate results for the sensors based on platinum-functionalized structures. The method presented here, which includes the fabrication of the whole flexible gas sensing device and the integration of functional nanostructures without the use of transfer methods, provides a simpler, faster and inexpensive method for the fabrication of highly functional flexible microsystems for gas sensing.

• Klíčová slova
• Flexible gas sensors, Functionalization, Nanostructures, VOC,
• Publikační typ
• časopisecké články MeSH

Nanoscale heterostructures based on WO3-x nanoneedles functionalized with Fe2O3 nanoparticles are integrated directly into flexible polymer-based transducing platforms via aerosol-assisted chemical vapor deposition. Results demonstrate that the incorporation of Fe2O3 nanoparticles at the surface of WO3-x nanoneedles enhances the electronic and sensing properties of WO3-x, providing a 6-fold increase in sensitivity to toluene and low cross-sensitivity to hydrogen and ethanol. These enhanced-sensing properties are comparable to those obtained via functionalization with precious metal (Pt) nanoparticles, which are commonly used to enhance sensor performance.

• Klíčová slova
• AACVD, ferric oxide, flexible gas sensors, toluene, tungsten oxide,
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

MicroRNAs (miRNAs) are small non-coding RNAs (18-22 nucleotides) that regulate gene expression and are associated with various diseases, including Laryngeal Cancer (LCa), which has a high mortality rate due to late diagnosis. Traditional methods for miRNA detection present several drawbacks (time-consuming steps, high cost and high false positive rate). Early-stage diagnosis and selective detection of miRNAs remain challenging. This study proposes a 3D flexible biosensor that combines nanofibers (NFs), gold nanoparticles (AuNPs), and an inverse molecular sentinel (iMS) for enzyme-free, SERS-based detection of miRNA-223-3p, evaluated as a potential LCa biomarker. The electrospun flexible nanofibers decorated with AuNPs enhance Raman signal. Selective detection of miRNA-223-3p is achieved by immobilizing an iMS-DNA probe labeled with a Raman reporter (Cyanine 3) on the AuNPs. The iMS distinctive stem-and-loop structure undergoes a conformational change upon interaction with the miRNA-223-3p, producing an "on to off" SERS signal. The proposed sensor demonstrated a linear detection range from 10 to 250 fM, with a limit of detection (LOD) of 19.50 ± 0.05 fM. The sensor selectivity was confirmed by analyzing the SERS signal behaviour in the presence of both Non-complementary miRNA and miRNA with three mismatched base pairs. This easily fabricable sensor requires no amplification and offers key advantages, including sensitivity, flexibility, and cost-effectiveness.

• Klíčová slova
• Flexible sensors, Laryngeal Cancer, Nanofiber, SERS, miRNA-223-3p,
• MeSH
• biosenzitivní techniky * metody   MeSH
• časná detekce nádoru metody   MeSH
• kovové nanočástice * chemie   MeSH
• lidé MeSH
• limita detekce MeSH
• mikro RNA * analýza   genetika   MeSH
• nádory hrtanu * diagnóza   genetika   MeSH
• nanovlákna * chemie   MeSH
• Ramanova spektroskopie * metody   MeSH
• zlato * chemie   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• mikro RNA * MeSH
• MIRN223 microRNA, human MeSH Prohlížeč
• zlato * MeSH

In this study, novel flexible micro-scale humidity sensors were directly fabricated in graphene oxide (GO) and polyimide (PI) using ion beam writing without any further modifications, and then successfully tested in an atmospheric chamber. Two low fluences (3.75 × 1014 cm-2 and 5.625 × 1014 cm-2) of carbon ions with an energy of 5 MeV were used, and structural changes in the irradiated materials were expected. The shape and structure of prepared micro-sensors were studied using scanning electron microscopy (SEM). The structural and compositional changes in the irradiated area were characterized using micro-Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), Rutherford back-scattering spectroscopy (RBS), energy-dispersive X-ray spectroscopy (EDS), and elastic recoil detection analysis (ERDA) spectroscopy. The sensing performance was tested at a relative humidity (RH) ranging from 5% to 60%, where the electrical conductivity of PI varied by three orders of magnitude, and the electrical capacitance of GO varied in the order of pico-farads. In addition, the PI sensor has proven long-term sensing stability in air. We demonstrated a novel method of ion micro-beam writing to prepare flexible micro-sensors that function over a wide range of humidity and have good sensitivity and great potential for widespread applications.

• Klíčová slova
• carbon ion micro-beam writing, graphene oxide, humidity sensors, polymers,
• Publikační typ
• časopisecké články MeSH

This study reports the possibility of using biaxially oriented polyethylene terephthalate (BOPET) plastic packaging to convert mechanical energy into electrical energy. Electricity is generated due to the piezoelectricity of BOPET. Electricity generation depends on the mechanical deformation of the processing aids (inorganic crystals), which were found and identified by SEM and EDAX analyses as SiO2. BOPET, as an electron source, was assembled and tested as an energy conversion and self-powered mechanical stimuli sensor using potential applications in wearable electronics. When a pressure pulse after pendulum impact with a maximum stress of 926 kPa and an impact velocity of 2.1 m/s was applied, a voltage of 60 V was generated with short-circuit current and charge densities of 15 μAcm-2 and 138 nCm-2, respectively. Due to the orientation and stress-induced crystallization of polymer chains, BOPET films acquire very good mechanical properties, which are not lost during their primary usage as packaging materials and are beneficial for the durability of the sensors. The signals detected using BOPET sensors derived from pendulum impact and sieve analyses were also harvested for up to 80 cycles and up to 40 s with short-circuit voltages of 107 V and 95 V, respectively. In addition to their low price, the advantage of sensors made from BOPET plastic packaging waste lies in their chemical resistance and stability under exposure to oxygen, ultraviolet light, and moisture.

• Klíčová slova
• biaxially oriented polyethylene terephthalate, flexible sensor, harvesting, piezoelectricity,
• Publikační typ
• časopisecké články MeSH

This review summarizes principles and current stage of development of fiber-optic chemical sensors (FOCS) and biosensors (FOBS). Fiber optic sensor (FOS) systems use the ability of optical fibers (OF) to guide the light in the spectral range from ultraviolet (UV) (180 nm) up to middle infrared (IR) (10 μm) and modulation of guided light by the parameters of the surrounding environment of the OF core. The introduction of OF in the sensor systems has brought advantages such as measurement in flammable and explosive environments, immunity to electrical noises, miniaturization, geometrical flexibility, measurement of small sample volumes, remote sensing in inaccessible sites or harsh environments and multi-sensing. The review comprises briefly the theory of OF elaborated for sensors, techniques of fabrications and analytical results reached with fiber-optic chemical and biological sensors.

• Klíčová slova
• chemical sensor, enzymatic sensor, fiber-optic sensor, immobilization of biologicals, tapered optical fiber, whole cell biosensor,
• MeSH
• biosenzitivní techniky přístrojové vybavení   MeSH
• biotest přístrojové vybavení   MeSH
• chemické techniky analytické přístrojové vybavení   MeSH
• design vybavení MeSH
• lidé MeSH
• optická vlákna * MeSH
• technologie optických vláken přístrojové vybavení   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• přehledy MeSH

This work focuses on an inkjet-fabricated sensor based on copper oxide nanostructured particles on polymer flexible substrate for the sensing of alcohol vapours and humidity at room temperature. Nanoparticles were prepared by a microwave-assisted solvothermal sealed vessel synthesis method. The ink composition was developed on the basis of viscosity and surface tension optimization by the addition of polymeric steric surfactant and dispersant. The printing process was optimized with the help of non-dimensional criteria. Silver nanoink was used for the printing of an interdigitated pattern on a PET substrate which was overprinted by the copper oxide ink, thus obtaining a flexible flat sensor. Material design and all fabrication steps of the sensor respected the temperature limitation given by the thermal stability of the polymer substrate. Printed layers and motifs were characterized microscopically and by resistance measurement. The effectiveness of the prepared sensor was demonstrated and studied by measuring the response to saturated vapours at room temperature. The sensing layer showed the opposite resistance response to stimuli than expected for the well-known p-type sensing mechanism of CuO sensors operated at high temperatures. In addition to vapour sorption, condensation and desorption influencing electron, proton and ionic conductivity, manifestation of another mechanism was observed and an explanation suggested in terms of the electrochemical mechanism.

• Klíčová slova
• copper oxide, gas sensor, inkjet, low temperature, nanoparticles, polymer substrate, sensing mechanism,
• Publikační typ
• časopisecké články MeSH

Structured illumination microscopy (SIM) has grown into a family of methods which achieve optical sectioning, resolution beyond the Abbe limit, or a combination of both effects in optical microscopy. SIM techniques rely on illumination of a sample with patterns of light which must be shifted between each acquired image. The patterns are typically created with physical gratings or masks, and the final optically sectioned or high resolution image is obtained computationally after data acquisition. We used a flexible, high speed ferroelectric liquid crystal microdisplay for definition of the illumination pattern coupled with widefield detection. Focusing on optical sectioning, we developed a unique and highly accurate calibration approach which allowed us to determine a mathematical model describing the mapping of the illumination pattern from the microdisplay to the camera sensor. This is important for higher performance image processing methods such as scaled subtraction of the out of focus light, which require knowledge of the illumination pattern position in the acquired data. We evaluated the signal to noise ratio and the sectioning ability of the reconstructed images for several data processing methods and illumination patterns with a wide range of spatial frequencies. We present our results on a thin fluorescent layer sample and also on biological samples, where we achieved thinner optical sections than either confocal laser scanning or spinning disk microscopes.

• MeSH
• kalibrace MeSH
• kapalné krystaly chemie   MeSH
• křemík chemie   MeSH
• mikroskopie přístrojové vybavení   MeSH
• ohebnost (fyzika) MeSH
• osvětlení přístrojové vybavení   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• křemík MeSH

Wearable sensors have made significant progress in sensing physiological and biochemical markers for telehealth. By monitoring vital signs like body temperature, arterial oxygen saturation, and breath rate, wearable sensors provide enormous potential for the early detection of diseases. In recent years, significant advancements have been achieved in the development of wearable sensors based on two-dimensional (2D) materials with flexibility, excellent mechanical stability, high sensitivity, and accuracy introducing a new approach to remote and real-time health monitoring. In this review, we outline 2D materials-based wearable sensors and biosensors for a remote health monitoring system. The review focused on five types of wearable sensors, which were classified according to their sensing mechanism, such as pressure, strain, electrochemical, optoelectronic, and temperature sensors. 2D material capabilities and their impact on the performance and operation of the wearable sensor are outlined. The fundamental sensing principles and mechanism of wearable sensors, as well as their applications are explored. This review concludes by discussing the remaining obstacles and future opportunities for this emerging telehealth field. We hope that this report will be useful to individuals who want to design new wearable sensors based on 2D materials and it will generate new ideas.

• Klíčová slova
• Materials for devices, Two-dimensional materials,
• Publikační typ
• časopisecké články MeSH
• přehledy MeSH