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Abstract. This paper describes a study, which proposes an alternative and safe energy source, namely, a flexible aluminium-air battery that is suited for use in special garments and wearable products, particularly those worn by children. The need for such a battery has arisen in our recent study, in which we have developed a textile-circuitbased enuresis alarm system. The system is primarily intended for use by children while they sleep, hence the use of lithium ion or other traditional batteries poses serious safety risks. The proposed battery uses saline electrolyte and all of its elements are flexible, which makes it particularly suitable for use in such specialized arrangements, where the appearance of a physiological or other type of saline electrolyte (urine, sweat, blood) energizes and activates the system. This paper studies constructive particularities of such a battery, arrangement of its components, as well as electrical properties and possible applications in medical and smart childcare products, e.g., the enuresis alarm system, smart diapers etc. Methods of integration of the developed batteries in textile products are described, which are based on our previous experience and studies. The developed battery enables one to replace a split "sensor/processing unit" system with an energy source, which actively reacts to changes in its environment and generates electricity. Low costs of the proposed battery, as well as the availability of its main components, make it perfect for wide range of applications from human and animal care to consumer products.Keywords: aluminium-air battery, flexible battery, smart textiles, embroidery. IntroductionIn one of our previous studies, we developed a textile enuresis alarm for children [1], which is intended to be worn by children during their sleep in order to treat enuresis. One of the main issues that has arisen during the study was related to the energy source. The system had to be autonomous and it was not feasible to use external power supply. Most commercially available chemical energy sources pose a certain degree of hazard due to their components -they either contain toxic materials or even pose explosion risk if not wired properly. One of the most promising alternatives was to use aluminium-air batteries due to the advantages described below. Besides that, since these batteries can be used with saline electrolytes, it is possible to use urine or other physiological liquids for their activation. As can be seen in the experimental results below, the activation of the battery is rather fast after the liquid is applied.Aluminium-air batteries are becoming more and more popular lately due to various factors, the major two being the abundance of aluminium in the Earth crust, hence its low price, and its relatively high theoretical voltage and energy density [2; 3].Another major advantage of aluminium-air batteries is that they can be made using safe and nontoxic materials. A basic design consists of an aluminium anode and a cathode, which needs to draw oxygen for ...

In order to improve the tactile perception, as well as other comfort properties of modern smart clothing, conventional electrical wires, which are used to connect integrated electronic components, are more and more often replaced by conductive threads. Conductive threads can be used to replace mounting wires in smart clothing, as well as to make sensors. In order to determine the durability of conductive threads made by different manufacturers, a study was conducted in which the conductive threads, which were integrated using embroidery technique, were subjected to multiple washing cycles. After each washing cycle electrical resistance of connections, made by these threads, was measured and its changes were compared. Suggestions about the use of different conductive threads can be found in the conclusions section of this study.

In order to improve comfort of smart garment, rigid electronic boards can be replaced with textile circuits, which use conductive yarns. When one tries to improve wearing comfort, often the most problematic items turn to be connection points of the electronic circuitry. The aim of this research is to determine behaviour of conductive yarns after they have been sewn into textile material, as well as to determine their suitability for the intended applications. In order to determine the quality of a conductive connective seams resistance has been measured (in Ω) under the influence of various variable factors: type of yarn, length of stitch, number of layers, type of seam. Besides that seam durability tests were carried, which show resistance changes over time and after washing.

There is one component that virtually any embedded wearable needs—a power source. This paper proposes an energy source, which contains no harmful substances, can be stored in a stand-by dry state for indefinite time period, is flexible and has tactile characteristics similar to that of textile. The main feature of this energy source is the separation of the electrolyte and the electrodes—the electrolyte is applied only when the battery needs to be activated. This makes storage time in a dry state virtually infinite. It expands their potential use to storage solutions and healthcare/health monitoring solutions, because the design of the battery allows it to be used as an active sensor, which generates electric current, when it detects liquid. We stress that this solution is suitable for specific applications only, outlined in the paper. The main components of the battery include aluminium anode, air cathode and the cotton shell. The design includes only textile-based materials, which ensure greater flexibility and better fusion with textile materials, where the battery is intended to be integrated. Besides that, results of the experiments with multi-cell battery prototype are presented.

The intelligent systems of smart textile should contain flexible electronics, for example, sewn or stitched textile elements that function as conductive traces, sensor elements, electrodes or switches. The experiments for development of sewn touch and push switches are performed. For this reason silver coated multifilament polyamide and multifilament stainless steel yarns were used and their properties and suitability tested. Tests include the changes of electrical resistance of yarns during tension, measurements of yarn voltage loss at 50 mA current; experiments to assess the yarn suitability for sewing; reliability tests of switches during use.