Implantable medical devices help diagnose and treat serious health conditions ranging from anatomical abnormalities to cardiovascular illnesses and kidney diseases. Commonly used devices include implantable cardioverter defibrillators, pacemakers, intra-uterine devices, spine crews, hip implants, metal screws, and artificial knees. Recent years have seen a significant increase in the use of such implants, which has led to the creation of several innovative products with improved function. Batteries play a crucial role in the successful operation of certain implantable devices. Most products rely on lithium cells that are powerful and easy to use. These electrochemical power sources can, however, lead to toxic side effects. Some patients may also experience biocompatibility issues. Healthcare professionals, nonetheless, had limited options, at least until now.

The 3D Printed Battery

Researchers at Carnegie Mellon University are aiming to overcome the drawbacks associated with traditional batteries by developing biodegradable versions made from natural ingredients. They have developed a prototype battery that can provide 5 milliWatts of power for up to 18 hours. This energy is enough to deliver medications slowly over a span of several hours or to detect the growth of pathogenic bacteria within the body.

The battery is made from melanin pigment found in skin, hair and nails. The pigment protects the body by absorbing ultraviolet light and toxic free radicals. It also has the ability to bind to metallic ions and can therefore, transform into the perfect battery material. While melanin can form either the anodic or the cathodic terminal of the battery, magnesium oxide is used as the second terminal and the GI fluid comprises the electrolyte. The materials are housed in a three-dimensional (3D) printed capsule made from polylactic acid, or PLA.

A 3D printer allows researchers to deposit the desired materials on a substrate in a specific pattern. It was invented in the 1980s to create engineering prototypes. Soon, researchers began using 3D printers in the field of medicine to improve patient outcomes. The technology helps customize the shape and the size of the outer capsule as per the needs of the consumer. The 3D printed capsule maintains the structural integrity of the battery and allows it to glide smoothly through the device. The capsule can dissolve quickly once it completes the essential functions. Other natural components within the battery can also degrade without producing any toxic side effects.

The Future

Currently, most ingestible and degradable probes and drug delivery systems remain in the body for about 20 hours. Although melanin batteries are less powerful when compared to their lithium counterparts, researchers believe that they could work very well with devices that remain in the body for only a few hours. The new battery is in the initial stages of development and will need to undergo extensive clinical testing before actual use. Nonetheless, it is a step in the right direction. Eventually, it may be possible to create more powerful versions of edible batteries that can support all types of medical devices, irrespective of their duration of use.