by Michael D’Agati

The field of bioelectronics, which produces implantable devices for sensing and therapeutics, has recently become a popular field. There is high promise in the collaboration between biology and electronics, but in order for these new innovations to work, a power source, such as implantable batteries, must be present to supply the energy needed. Currently, implantable batteries require bulky metal cases to keep the battery’s toxic electrolytes and immunogenic active materials from leaking inside the human body.

To fix the toxicity and size issues, Dr. Craig Milroy and Dr. Arumugam Manthiram from the University of Texas at Austin have developed a fabrication method exclusively using endogenous biomolecules. Endogenous biomolecules are molecules that originate from within an organism, tissue, or cell. The endogenous biomolecules allow the implantable battery to be fully biocompatible, since they are similar to molecules that already exist or are produced by the human body. These biomolecules were created using a one-step combination of dopamine (DA) to hyaluronic acid (HA). This composite still allows the battery to perform well with long-term electroactivity for 400 cycles, meaning that the endogenous biomolecules are able to still exhibit electrical activity even after 400 cycles of charging and discharging the device. The biomolecule’s p(DAHA) biopolymer also exhibits stability and high pseudocapacitance, or electrochemical storage. These attributes show promise for the usage of endogenous biomolecules in a bioelectronic energy storage device, such as a supercapacitor or an implantable biobattery.

The ability to create biocompatible batteries and other implantable energy storage devices is encouraging for the future of not only energy storage devices themselves, but also new implantable medical technologies for the future. By advancing the characteristics of energy storage devices, other innovations in many medical applications can advance as well. An example of this is implantable sensors, which could now have a battery that could supply the power needed from directly inside the body.

References:  

1. C.A. Milroy, A. Manthiram, Bioelectronic energy storage: a pseudocapacitive hydrogel composed of endogenous biomolecules. ACS Energy Letters 1, 672-677(2016). doi: 10.1021/acsenergylett.6b00334.
2. Image retrieved from: https://pixabay.com/en/man-muscular-robot-cyborg-android-320276/