It is large, indeed as small as a speck of dust, but has a slightly higher voltage than that of a normal AAA battery (ie 1.6 Volts), even if it is less powerful. The new battery with the technology of “nano-bio-supercapacitors” was born thanks to the joint work of the three research centers of Dresden: the Technological University of Chemnitz, IFW Dresden and IPF Dresden led by Oliver G. Schmidt.
The result is significant not only for the sub-millimeter size of the nano-batteries, but also because they are fully bio-compatible. That is, they are designed to feed autonomous microsystems to be used in the human body without causing any negative reaction.
Usually, in fact, even microscopic batteries use components such as corrosive electrolytes that not only discharge quickly if immersed in a liquid but that pollute it and, in the case of the human body, would poison it. Instead, research carried out in Dresden has found a solution to build new types of micro batteries using materials that are biocompatible and can be miniaturized thus becoming a key component for the development of microscopic medical equipment.
In fact, these microscopic bio-supercapacitors are intended to provide a stable power source compatible with the requirements necessary to power appliances dedicated to human health: intravascular implants and microbiotic systems that can reach (and operate) in areas within the human body. difficult to reach.
In the study, presented in Nature Communications by the Dresden researchers, for example, a sensor integrated with the micro battery capable of measuring the pH values of the blood within the circulatory system is hypothesized, which allows for example to identify the development of some types of cancer in its early stages.
The basic requirement for any micro machine (and micro battery) to function inside a person is the ability to resist in a “difficult” environment such as that of the human body. On scale, in fact, the stresses produced by the muscles and the human circulatory system are particularly intense. For this reason, the microscopic tubular-shaped batteries, with a volume of one nanoliter, that is a thousandth of a cubic millimeter, have been made with particular materials and construction and structural techniques to make them capable of withstanding the impact of enormous mechanical stresses at those dimensions. Such as, for example, the pressure resulting from muscle contractions or heart beats, which push blood throughout the body, feeding the circulatory system.
A significant innovation in the study of these batteries, according to the researchers, is that the environment itself provides an advantage to the batteries by increasing conductivity and preventing self-discharge (a phenomenon typical of a battery inserted in a conductive environment). In other words, it is the environment of the human body and its bio-electrochemical reactions that lend a hand to the batteries, increasing efficiency by up to 40%. In fact, nanotechnologies are capable of exploiting both the enzymatic redox reactions and the presence of living cells in the body to function better.
“The architecture of our nano-bio supercapacitors – said Vineeth Kumar, researcher in the team that made the batteries – offers the first potential solution to one of the biggest challenges of biomedicine: tiny integrated energy storage devices that allow the self-sufficient operation of multifunctional microsystems “.
Previous generation biocompatible batteries had a much larger volume, to scale: three cubic millimeters. In addition, the new batteries are made with materials that have a flexible tubular geometry, which is one of the “secrets” for which the battery is able to withstand the pressures to which the elements present in the human body are subjected. It is in fact a structural technology called Origami as the oriental art of folding paper: the materials of the battery components are assembled by flexing them and joining them under a strong mechanical tension in such a way that, subsequently, when the tension is released, the parts enter into contact in a firmer and more stable way.
The batteries have not yet been tested in a human body but only in environments that simulate human conditions, with different types of saline solutions, in environments that simulate human veins (channels for microfluids with diameters from 0.12-0.15mm ) and in conditions of pressure and flow comparable to those of a human organism.