In China, researchers have developed a thin, flexible device designed as an alternative to lithium-ion batteries and a potential power source for wearables and implants. It can run on biocompatible liquids like intravenous (IV) saline solution and cell cultures containing amino acids, sugars, and vitamins.
"Current batteries like the lithium-ion ones used in medical implants generally come in rigid shapes," says Yonggang Wang, co-senior author of a paper on the battery and a chemistry professor at Fudan University and the Collaborative Innovation Center of Chemistry for Energy Materials. "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 researchers built two flexible versions of their battery, one shaped like a belt and the other like a coiled cable - a woven carbon nanotube fiber backbone with embedded nanoparticle electrode materials. According to the researchers, testing showed their battery outperformed most current lithium-ion batteries used in wearables in terms of power output and charge.
For more on this development, see " Multi-functional Flexible Aqueous Sodium-Ion Batteries with High Safety ."
Meanwhile,researchers at Binghamton University, State University of New York have developed a battery activated by saliva and aimed at powering next-generation, disposable point-of-care (POC) diagnostic biosensors. Their paper-based biobattery is designed for use in extreme conditions where normal batteries don't function.
"On-demand micro-power generation is required especially for point-of-care diagnostic applications in developing countries," says Binghamton University Electrical and Computer Science Assistant Professor Seokheun Choi. "Typically, those applications require only several tens of microwatt-level power for several minutes, but commercial batteries or other energy harvesting technologies are too expensive and over-qualified. Also, they pose environmental pollution issues."
The bacteria-powered battery is comprised of microbial fuel cells with inactive, freeze-dried exoelectrogenic cells, resulting in a long shelf life. It can begin generating power within minutes of being rehydrated by adding saliva.