Flexible aluminium-air battery for enuresis alarm system

Abstract

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 ...

Development of flexible textile aluminium-air battery prototype

“…In this paper, we focus in particular on a new approach to the development of energy source for smart textiles that is based on the idea of electrolyte and electrode separation [11]. This approach has a number of advantages, such as indefinite storage time and the possibility to use this battery as a self-energised wetness sensor [10]. This enables to use the proposed design in medical applications, which often require a reaction to the appearance of bodily fluids.…”

“…The battery described in [11] is completely made from textile-based materials. Silver-coated permeable fabric is used as cathode current collector, which eliminates problems with oxidation, that the original copper current collector was prone to [10]. Besides that, its characteristics are comparable to that of the original battery, made using metal meshes.…”

“…The original battery [10] consists of a copper mesh cathode with carbon granules, and an aluminium mesh anode. The single-cell battery has shown promising results (open-circuit voltage V OC = 800 mV, short-circuit current I SC = 50 mA) [10].…”

“…The original battery [10] consists of a copper mesh cathode with carbon granules, and an aluminium mesh anode. The single-cell battery has shown promising results (open-circuit voltage V OC = 800 mV, short-circuit current I SC = 50 mA) [10]. Although the choice of the materials made the battery less flexible, so further studies have been conducted, which resulted in replacing all the metal meshes with alternative textile-based materials, without sacrificing the performance [11].…”

“…The current study described in this paper is based on our previous work. More specifically, the original flexible aluminium-air battery was a combination of metal meshes and textile materials [10]. This design was later improved by replacing pure metal meshes with metal-coated textile materials [11], which ensured better flexibility and eliminated problems with copper mesh oxidation.…”