Researchers developed a biocompatible nanoscale supercapacitor that can power implantable sensor systems.
Microelectronic sensor technology is progressing towards ever-decreasing size of devices. With this, biomedical implants are a possibility. This poses a challenge of tiny but efficient energy storage devices that enable the operation of autonomously working microsystems. If the device has to be implanted inside a human body, the storage solution has to be biocompatible as well.
A research team led by Prof. Dr. Oliver G. Schmidt, Professorship of Materials Systems for Nanoelectronics at Chemnitz University of Technology, initiator of the Center for Materials, Architectures and Integration of Nanomembranes (MAIN) at Chemnitz University of Technology and director at the Leibniz Institute for Solid State and Materials Research (IFW) Dresden, have developed a prototype that combines the aforementioned essential properties.
In their paper published in Nature Communications, researchers report on their smallest microsupercapacitors, which can be used as an energy source for tiny sensor systems like for measuring pH in blood vessels. According to the researchers, the biocompatible supercapacitors open up possibilities for intravascular implants and microrobotic systems for next-generation biomedicine that could operate in hard-to-reach small spaces deep inside the human body.
“It is extremely encouraging to see how new, extremely flexible, and adaptive microelectronics is making it into the miniaturized world of biological systems,” says research group leader Prof. Dr. Oliver G. Schmidt.
The nanoscale supercapacitors developed are fully biocompatible, and they can compensate for self-discharge behavior through bio-electrochemical reactions. In this way, they benefit from the body’s own reactions, because redox enzymatic reactions, in addition to typical charge storage reactions in capacitors, and living cells naturally present in the blood increase the performance of the device by 40%.
Researchers succeeded in producing nano-biosupercapacitors (nBSCs) with a volume of 0.001 mm3 (1 nanoliter), which occupies less space than a grain of dust and yet delivers up to 1.6V supply voltage.
This miniaturization is possible due to the origami structure technology which involves placing the materials required for the nBSC components on a wafer-thin surface under high mechanical tension. When the material layers are detached in a controlled manner, the strain energy is released and the layers wind themselves into compact 3D devices with high accuracy and yield.
The researchers tested their prototype in blood, where it showed excellent lifetime, holding up to 70% of its initial capacity even after 16 hours. In this case, a proton exchange separator (PES) was used to suppress the rapid self-discharge.
This advancement opens up a wide range of possible applications, for example in diagnostics and medication.