May be available soon Disposable paper battery, which is activated by a few drops of water and which can be used to power a wide range of low-power single-use electronic devices: from smart object-tracking tags to environmental sensors to small medical diagnostic devices. They described it in a study published in the journal Scientific Reportsand researchers Swiss Federal Laboratory for Sciences and material technology, It also explains how it works. Since it is biodegradable, the use of the battery will allow to reduce the environmental impact of the devices. A battery consists of at least one square centimeter cell, made up of three different types of inks printed on a small rectangular strip of paper. The sodium chloride salt is applied to the entire strip and one of its shorter ends is dipped in wax. On one side of the paper, the first ink containing graphite flakes is printed, which serves as the positive electrode for the battery, while the ink containing zinc dust is placed on the other side, which serves as the negative electrode. Finally, the third ink is printed on both, and contains flakes of graphite and carbon black (pigment), the task of which is to connect the electrodes to two circuits located at the end moistened with wax. The device can be connected to these two circuits. The researchers, led by Alexander Paulin, made a battery consisting of two core cells, and connected it to an alarm clock with a liquid crystal display. Two drops of water, dissolve the salt and thus allow the release of charged ions, allowing the battery to activate within 20 seconds and to set the alarm for about an hour. After that time, the dry leaf caused the battery performance to drop significantly, but adding two more drops of water allowed it to continue working for another hour.