A very simplified synthetic model battery has been developed by scientists from the Yale University and the National Institute of Standards and Technology. The cells are based on organic substances and can generate power for minuscule devices.
The new biological cell is made of a droplet of a water-based solution that contains a salt-potassium and chloride ions, enclosed within a wall made of a lipid – a molecule with one end attracted to the water molecules, and the other end repelling them. When two of such cells touch each other, the water repelling end that form their outsides touch, creating a stable double bilayer separating the two cells’ interiors, just like biological cell membranes do.
Next, the researchers inserted into the bilayer a modified form of a protein, called alpha-hemolysin, produced by the bacterium Staphylococcus aureus. The embedded proteins create pores acting as channels for ions, and mimic the pores in a normal biological cell. “This preferentially allows either positive or negative ions to pass through the bilayer and creates a voltage across it,” LaVan said. “We can harness this voltage to generate electric current,” he added.
If the solutions in the two cells start with different salt concentrations, then poking thin metal electrodes into the droplets creates a small battery.
A battery made this way with only two droplets 200 nanoliters of solution each could deliver a voltage for about 10 minute, while an 11 microliters one lasted for more than four hours.
What does this battery bring new? If we refer to the volumetric efficiency it’s not its strong spot – the battery is only 1/20 as effective as a conventional lead-acid battery, but if we refer to its ability to transform chemical into electrical energy, the synthetic cell is 10% efficient, comparable to solid-state devices that convert heat, light, or mechanical energy into electricity.
I still don’t agree with that Staphylococcus aureus-based substance, since as we all know, it is considered a biohazard (you’ll understand if you ever had problems with it). It is still, a common bacterium, but if imbalanced it could cause deadly epidemics.