Combining miniature electronics with the art of origami, scientists from Germany have developed what they say is the world's smallest microsupercapacitor. This revolutionary energy storage device is not only safe for use in the human body, but also uses key blood ingredients to boost its efficiency.
The scientists who created the new device worked in the field of nano-supercapacitors (nBSCs), which are conventional capacitors but reduced to the sub-millimeter scale. Developing such devices is challenging enough, but the researchers sought to create a device that could safely work in the human body to power tiny sensors and implants, which in turn requires replacing problematic materials and corrosive electrolytes with biocompatible ones.
These devices are known as biosupercapacitors, and the smallest commercially available devices developed to date are larger than 3 mm3. But in this case, scientists have taken a huge leap forward in how tiny biosupercapacitors can be. The design begins with a stack of polymer layers that are interconnected by a light-sensitive photoresist material that acts as a current collector, a separating membrane and electrodes made of the electrically conductive biocompatible polymer PEDOT:PSS.
This stack is placed on a thin plate surface, which is subjected to high mechanical stress, causing the different layers to separate in a strictly controlled manner and folded origami-like into a nano-biosupercapacitor of 0.001 mm volume3, which takes up less space than a dust particle. Thus, these tubular biosupercapacitors are 3000 times smaller than previously developed, but have about the same voltage as a AAA battery (although with much less actual current).
These tiny devices have been placed in saline, blood plasma and blood, where they have demonstrated the ability to successfully store energy. The biosupercapacitor was particularly effective specifically in blood, where it retained up to 70 percent of its capacity after 16 hours of operation. Another reason blood may be a suitable home for a biosupercapacitor is that the device works with inherent redox enzymatic reactions and live cells in solution to recharge its own charge storage reactions, which increases its capacity by 40 percent.
The full paper can be accessed at.