A revolution in battery technology is brewing and it could make non-toxic, recyclable batteries the norm.
Scientists in China have developed a thin, flexible battery powered by body-friendly fluids – namely, saline (or intravenous) solution and cell-culture medium – that could be perfect for wearables and implantable medical devices.
"Current batteries like the lithium-ion ones used in medical implants generally come in rigid shapes," said team lead Yonggang Wang of Fudan University in Shanghai. "Additionally, most of the reported flexible batteries are based on flammable organic or corrosive electrolytes, which suffer from safety hazards and poor biocompatibility for wearable devices, let alone implantable ones."
The use of sodium-based electrolytes that are neither corrosive nor toxic reduces the dangers associated with leaks when they do occur, while the flexibility could see these new batteries used in far more products than lithium-ion batteries, like .
Bending over backwards
Having done away with dangerous electrolytes, the team had the freedom to build batteries that didn’t need to have excessive structural reinforcements, leading to the creation of two flexible designs – a belt-like shape, made of thin films of electrode material stuck on a steel mesh, and a woven carbon nanotube fiber backbone embedded with nanoparticle electrode materials.
During testing, both batteries came out with flying colours, outperforming most lithium-ion batteries currently used in wearables in terms of power output and amount of charge they can hold.
The accidental cancer treatment
Not only did the concept batteries outperform traditional batteries, the nanotube fiber version accelerated the conversion of dissolved oxygen into hydroxide ions. In simple words, starved the electrolyte of oxygen.
Even though this reduces the battery’s effectiveness, deoxygenation is perfect for cancer starvation therapy.
"We can implant these fiber-shaped electrodes into the human body to consume essential oxygen, especially for areas that are difficult for injectable drugs to reach," explained Wang. "Deoxygenation might even wipe out cancerous cells or pathogenic bacteria since they are very sensitive to changes in living environment pH. Of course, this is hypothetical right now, but we hope to investigate further with biologists and medical scientists."
Just spit on it
Meanwhile, researchers at Binghamton University in New York have created a paper-based battery that is powered by bacteria in saliva.
This new innovation, which could be pretty cheap to run, can power a single LED light for about 20 minutes with just one drop of spit.
According to Professor Seokheun Choi, co-author of , “This is all about a disposable, easy-to-use, and portable bio-battery that can generate power from bacterial metabolism. This battery is ready to operate with human body fluids like saliva for on-demand power generation for other disposable low-power applications such as biosensors.”
So there may come a day when all we’ll need to power up our phones is some simple spit.