Stabilization and Incipient Carbonization of Electrospun Polyacrylonitrile Nanofibers Fixated on Aluminum Substrates

Storck JL, Grothe T, Tuvshinbayar K, et al. Stabilization and Incipient Carbonization of Electrospun Polyacrylonitrile Nanofibers Fixated on Aluminum Substrates. Fibers. 2020;8(9): 55.Polyacrylonitrile (PAN) nanofibers, prepared by electrospinning, are often used as a precursor for carbon nanofibers. The thermal carbonization process necessitates a preceding oxidative stabilization, which is usually performed thermally, i.e., by carefully heating the electrospun nanofibers in an oven. One of the typical problems occurring during this process is a strong deformation of the fiber morphologies—the fibers become thicker and shorter, and show partly undesired conglutinations. This problem can be solved by stretching the nanofiber mat during thermal treatment, which, on the other hand, can lead to breakage of the nanofiber mat. In a previous study, we have shown that the electrospinning of PAN on aluminum foils and the subsequent stabilization of this substrate is a simple method for retaining the fiber morphology without breaking the nanofiber mat. Here, we report on the impact of different aluminum foils on the physical and chemical properties of stabilized PAN nanofibers mats, and on the following incipient carbonization process at a temperature of max. 600 °C, i.e., below the melting temperature of aluminum

Microalgae growth and oxygen production on different textile fabrics

Microalgae can be used for diverse applications in research and industry. Several microalgae grow adhering to surfaces that are usually two-dimensional. A third dimension could increase the amount of microalgae adhering to a given area and can be offered by textile fabrics. Here we report on the microalgae Chlorella vulgaris and Scenedesmus spec. growing on different knitted fabrics under defined light and under office light conditions. Our results show a significant influence of illumination on both algal species and a smaller impact of the chosen medium, while all knitted fabrics under examination were found well suited as substrates. The numbers of alga cells per petri dish were higher on textile fabrics than in pure water or medium by a factor of ~ 4–20, respectively

50/60 Hz Power Grid Noise as a Skin Contact Measure of Textile ECG Electrodes

The electrocardiogram (ECG) is one of the most commonly measured biosignals. In particular, textile electrodes allow for the measuring of long-term ECG without skin irritation or other discomforts for the patient. Such textile electrodes, however, usually suffer from insufficient or unreliable skin contact. Thus, developing textile electrodes is impeded by the often-complicated differentiation between signal artifacts due to moving and breathing and artifacts related to unreliable skin contact. Here, we suggest a simple method of using 50/60 Hz power grid noise to evaluate the skin contact of different textile electrodes in comparison with commercial glued electrodes. We use this method to show the drying of wetted skin under an embroidered electrode as well as sweating of the originally dry skin under a coated electrode with high water vapor resistance

50/60 Hz Power Grid Noise as a Skin Contact Measure of Textile ECG Electrodes

The electrocardiogram (ECG) is one of the most commonly measured biosignals. In particular, textile electrodes allow for the measuring of long-term ECG without skin irritation or other discomforts for the patient. Such textile electrodes, however, usually suffer from insufficient or unreliable skin contact. Thus, developing textile electrodes is impeded by the often-complicated differentiation between signal artifacts due to moving and breathing and artifacts related to unreliable skin contact. Here, we suggest a simple method of using 50/60 Hz power grid noise to evaluate the skin contact of different textile electrodes in comparison with commercial glued electrodes. We use this method to show the drying of wetted skin under an embroidered electrode as well as sweating of the originally dry skin under a coated electrode with high water vapor resistance

Usability of Inexpensive Optical Pulse Sensors for Textile Integration and Heartbeat Detection Code Development

Low-cost sensors and single circuit boards such as Arduino and Raspberry Pi have increased the possibility of measuring biosignals by smart textiles with embedded electronics. One of the main problems with such e-textiles is their washability. While batteries are usually removed before washing, single-board computers and microcontrollers, as well as electronic sensors, would ideally be kept inside a user-friendly smart garment. Here, we show results of washing tests with optical pulse sensors, which can be used in smart gloves not only for hospitalized patients, and ATtiny85 as an example of a single-board microcontroller, sewn onto different cotton fabrics. We report that even without any encapsulation, all tested sensors and microcontrollers endured 10 washing cycles at 30–60 °C without defects. For easier garment integration, we suggest using an ESP8266 with integrated Wi-Fi functionality and offer a new program code to measure beats per minute (BMP) with optimized accuracy

Microalgae growth and oxygen production on different textile fabrics

Tanzli E, Brockhagen B, Post IB, et al. Microalgae growth and oxygen production on different textile fabrics. Communications in Development and Assembling of Textile Products. 2022;3(1):9-16.Microalgae can be used for diverse applications in research and industry. Several microalgae grow adhering to surfaces that are usually two-dimensional. A third dimension could increase the amount of microalgae adhering to a given area and can be offered by textile fabrics. Here we report on the microalgae Chlorella vulgaris and Scenedesmus spec. growing on different knitted fabrics under defined light and under office light conditions. Our results show a significant influence of illumination on both algal species and a smaller impact of the chosen medium, while all knitted fabrics under examination were found well suited as substrates. The numbers of alga cells per petri dish were higher on textile fabrics than in pure water or medium by a factor of ~ 4–20, respectively

Electrospinning Poly(acrylonitrile) Containing Magnetite Nanoparticles: Influence of Magnetite Contents

Alvarez AKG, Dotter M, Tuvshinbayar K, et al. Electrospinning Poly(acrylonitrile) Containing Magnetite Nanoparticles: Influence of Magnetite Contents. Fibers . 2024;12(3): 19.Magnetic nanofibers were prepared by electrospinning polymer/metal solutions of poly(acrylonitrile) (PAN) with magnetite (Fe3O4) nanoparticles. At a mass ratio of PAN:magnetite of 2:1, the total solid content in the dimethyl sulfoxide (DMSO) solution was varied between 15 wt.% and 25 wt.%, which represents the limits of the spinnable range. The results show that the most homogeneous nanofiber mats were 21 wt.% solid contents. At 15 wt.% solid contents, a nano-membrane with some fibrous regions was produced. Nanofibers at 25 wt.% had a much larger and more inhomogeneous diameter. Nevertheless, the magnetic properties of all samples were very similar, indicating that the distribution of magnetite nanoparticles in the fibers is comparable in all samples. The results also suggested that the samples spun from solutions with near-ideal solid contents (19-21 wt.%) contain agglomerations of the nanoparticles inside the nanofibers

Stabilization and Carbonization of PAN Nanofiber Mats Electrospun on Metal Substrates

Storck JL, Brockhagen B, Grothe T, et al. Stabilization and Carbonization of PAN Nanofiber Mats Electrospun on Metal Substrates. C: Journal of Carbon Research. 2021;7(1): 12.Polyacrylonitrile (PAN) nanofiber mats are typical precursors for carbon nanofibers. They can be fixed or even elongated during stabilization and subsequent carbonization to gain straight, mechanically robust carbon nanofibers. These processes necessitate additional equipment or are—if the nanofiber mats are just fixed at the edges—prone to resulting in the specimens breaking, due to an uneven force distribution. Hence, we showed in a previous study that electrospinning PAN on aluminum foils and stabilizing them fixed on these substrates, is a suitable solution to keep the desired morphology after stabilization and incipient carbonization. Here, we report on the influence of different metallic and semiconductor substrates on the physical and chemical properties of the nanofiber mats after stabilization and carbonization at temperatures up to 1200 °C. For stabilization on a metal substrate, an optimum stabilization temperature of slightly above 240 °C was found, approached with a heating rate of 0.25 K/min. Independent from the substrate material, SEM images revealed less defect fibers in the nanofiber mats stabilized and incipiently carbonized on a metal foil. Finally, high-temperature carbonization on different substrates is shown to allow for producing metal/carbon nano-composites