Zbigniew Stempien

An alternative instrumental method for fabric pilling evaluation based on computer image analysis

The present paper describes an instrumental method for the assessment of fabric pilling intensity, whose starting value is represented by the degree of fabric surface filling with pilling. This factor constitutes an alternative to the currently used scale of pilling evaluation in the form of pilling gradation and degree. The method is based on using the processing and analysis of the digital image of a pill-covered fabric sample. The measurement position described in the paper has been characterised paying attention to factors having a possible influence on the results of the tests performed. In respect of the relation between the pilling evaluation results obtained by the standard and instrumental methods, the results of the analysis show that there is a strong relationship between the parameters representing the measurement results in both the instrumental and standard methods. This confirms the solidity of using the instrumental method for the pilling evaluation of flat textiles.

Ammonia gas sensors ink-jet printed on textile substrates

This work describes the fabrication of ammonia gas sensors on textile substrates by using the reactive inkjet printing for the deposition the polyaniline gas sensing layers. These layers were printed over vacuum deposited gold electrodes designed for the purposes of sensor conductivity analysis. The sensing properties such as sensing linearity, response and recovery times were studied in the range of ammonia gas concentrations from 15 to 100 ppm. The fabricated sensors showed a relevant increase in relative resistance from 0.30 to 14.4 times after exposing to ammonia gas at the concentrations of 15–100 ppm for 120 sec.

Shape-programmed inkjet-printed silver electro-conductive layers on textile surfaces

The inkjet-printing technique was used to deposit a commercial silver nanoparticle ink in order to fabricate the electro-conductive layers directly on the different natural, synthetic, blend and mineral textile fabric surfaces with simultaneous sintering at 130℃ during printing process. This modification eliminated the necessity of sintering of silver prints in a box oven and significantly minimised ink spreading over the fabric. The silver nanoink used was characterised by means of ultraviolet-visible spectrometry, dynamic light scattering and transmission electron microscopy. The changes in surface resistance of the fabrics with the silver-deposited layers have been measured by means of the four-probe method. The morphology of the silver layers has been observed by optical microscopy and scanning electron microscopy. The conducting layers were also characterised chemically by means of energy dispersive spectroscopy. The changes in surface resistance of the silver inkjet-printed textiles were evaluated in the bending tests and after the rubbing, washing and dry-cleaning processes. The obtained results proved that the proposed shape-programmed inkjet-printing method was very simple, giving an excellent adhesion of the inkjet-printed silver layers to the substrates and ensuring a very low surface resistance. The studies have confirmed the usefulness of the ink applied for inkjet printing of silver electrodes and their good tolerance to bending, washing and dry-cleaning processes.

Woven Fabrics Containing Hybrid Yarns for Shielding Electromagnetic Radiation

The aim of the study was to verify whether the construction of a specific hybrid yarn containing a ferromagnetic core and electroconductive wire introduced into woven fabric will improve the shielding effectiveness (SE) in comparison with reference fabrics made of the same raw materials but introduced into woven fabrics as plain wefts, not twisted into the hybrid yarn. Hybrid yarn made of electroconductive materials allows the creation of a set of solenoids with a ferromagnetic core made of steel yarn and a solenoid of conductive effect yarns made of copper. The woven fabric made of these yarns placed into an alternating electromagnetic field (EMF) exhibits a phenomenon where an alternating electric voltage is generated between the ends of the copper solenoid, and alternating magnetisation of the ferromagnetic core takes place. Twelve fabrics were produced, nine of which differed in the density with which the hybrid yarns were introduced as wefts, i.e. once every 25×2 tex cotton yarn, every two cotton yarns, and every three cotton yarns, and the remaining three were reference fabrics, without hybrid yarn. It was found that if measured at a frequency of 30 MHz, the fabrics containing hybrid yarns had 60% higher SE than the reference ones.

Shielding of electromagnetic radiation by multilayer textile sets

This paper presents the continuation of research on shielding efficiency (SE) of electromagnetic radiation (EMR) by woven fabric made of cotton (warps and wefts) and a hybrid yarn (wefts). This hybrid yarn was made of stainless steel yarn by Bekinox wrapped with an enamelled copper wire from Synflex Elektro GmbH, Germany. The pitch of copper coil on a hybrid yarn equals 3 mm. The wefts were introduced into the fabric in the following order: 1 hybrid yarn, 1 cotton yarn, 1 hybrid yarn, 1 cotton yarn, etc. The construction of this specific fabric was proven to be the most efficient in terms of the hybrid weft construction and the fabric construction to shield EMR among other previously tested fabrics with different weft configuration. The current study proposes to verify the effect of the number of layers of the fabrics and their mutual configuration on the final SE of the multilayered set. Some of the most interesting findings of this study are that increasing the number of layers placed on top of one another with an offset angle of 0° to more than two does not provide a higher SE; however, using three such layers provides an SE of 56 dB, which is over two times higher than that provided by a single layer. Increasing the number of layers of fabric aligned at an angle of 45° provides a higher SE only for a frequency of 30 MHz.

Tetrazolium salts-Pluronic F-127 gels for 3D radiotherapy dosimetry

This work is a follow-up study for a recently-proposed 3D radiochromic gel dosimeter that contains a tetrazolium salt and a physical gel matrix made of poly(ethylene oxide)-block-poly(propylene oxide)-block-poly(ethylene oxide) (Pluronic F-127). Several tetrazolium salts were examined in this work, including tetrazolium violet, blue tetrazolium chloride, nitro blue tetrazolium chloride (NBT), tetranitro blue tetrazolium chloride (tNBT) and thiazolyl blue tetrazolium bromide (TBTB). The salt-containing gel dosimeters were compared with the first Pluronic gel composition that contained 2,3,5-triphenyltetrazolium chloride (TTC) as the radiation-sensitive component (dose sensitivity of 0.0023 (Gy cm)-1). The Pluronic gels with NBT and tNBT outperformed the other gels, including the TTC-containing gel, with respect to their dose sensitivity and low dose-response. The NBT gels were found to have better stability over time than tNBT gels. Sensitization of the gels to ionizing radiation was examined by addition of tert-butyl alcohol and sodium formate. The best composition was 0.0818% NBT (1 mM), 25% Pluronic F-127 and 0.136  ×  10-2% sodium formate. This gel dosimeter was insensitive to changes in dose rate for photons of different energies. The mean dose sensitivity amounted to 0.0047  ±  0.1  ×  10-4 (Gy cm)-1. A diversion in the dose-response was observed for the gel irradiated with electrons. Additional characteristics of the NBT gel were a linear-dose range and a dynamic-dose range between  <1 and  ⩾150 Gy and a dose threshold of  <1 Gy. The dose distribution registered for the NBT-Pluronic gel was stable after irradiation for over 7 d with no visible diffusion of the irradiated part, which is analogous to the original TTC-Pluronic gel.

Thin conductive structures on coated textiles

Among new areas of electronics the systems integrated with textile materials (textronics systems) grow particularly rapidly due to special properties like flexibility, low mass, and most of all, the possibility of integration with clothing, what guarantees their direct contact with the human body. Textronic systems can be developed by the intrinsic or external modifications of textiles and their composites. Three methods of creating passive elements of electronic circuits, namely PVD deposition of thin metal layers, laser direct writing and inkjet printing have been presented. The research program of manufactured elements described in the paper included the study of basic and working properties relevant for the applications. The selected applications of conductive structures on textiles or textile composites have been also discussed.