Nanobatteries that could be used to power tiny machines, a la the craft that traveled through human blood vessels in the classic sci-fi Fantastic Voyage, are in the works at the University of Tulsa. Chemistry professor Dale Teeters and researchers Nina Korzhova and Lane Fisher received a patent for a manufacturing process that can build, charge, and test nanobatteries. So far, Teeters and his team have made batteries that are so small more than 40 can stack across the width of a hair (the diameter of an average hair is 50,000 nm), and they continue to make even smaller versions. Through nanotechnology, objects are built so that nearly each atom is precisely placed. The process is similar to that of making a layered cake. If the finished product was enlarged, says Teeters, "it would look like a tray of flashlight batteries placed side by side."
Teeters' method involves using a porous membrane, filling the pores with an electrolyte, and capping the pores with electrodes. Conventional batteries have two electrodes that deliver the charge and an electrolyte through which charged ions move. The new manufacturing process starts with placing an aluminum sheet in an acid solution under an electric current, which creates an aluminum-oxide membrane. When the metal dissolves, a honeycomb structure appears. The pores are then filled with an electrolyte (comparable to the liquid in a car battery), which in this case is a plasticlike polymer. The filled pores are then capped on both sides with electrodes -- ceramic or carbon particles --, which function much like a car battery's lead plates and two posts.
A scanning electron microscope and an atomic force microscope are essential tools in the nanobattery-development process. The atomic force microscope not only is used to observe and manipulate particles as small as molecules, but also to charge the microscopic array of batteries. The microscope's custom-made electrically conducting cantilever tip contacts the electrode to charge and test the battery. Each battery packs about 3.5 V.
