Our squishy, salty brains are capable of doing incredible things – from commanding us to walk to solving complex questions about our world. Scientists and authors of science-fiction have longed to understand (and even) master our brains, but so far they are an incredibly complex utility to crack.
Intriguing is the development of a new, biocompatible polymer coating for electronic implants by a team of researchers at the University of Delaware could be the key to a better understanding of this biological black box.
These polymers would not only leave fewer scars on biological tissue than inorganic-coated electronics, but scientists would also be able to tune the sensitivities of polymers – which could create early warning systems for the presence of harmful diseases.
Furthermore, as these devices continue to mature, scientists say they may be the answer in creating an effective human brain AI interface in the future.
The lead author and professor of biomedical engineering at the University of Delaware, David Martin, explains Inverse that current technology is used to develop biocompatible electronics such as pacemakers, cochlear implants, and deep brain stimulations. Critically, these technologies come with limitations – Martin says his team’s innovation could be the fix.
“There are limitations in both the reliability and performance of the devices themselves,” says Martin. “Our materials are designed to bridge the gap between the inert, rigid, solid, abiotic engineered device and the living, soft, wet, biotic tissue.”
The materials scientists and engineers behind this study presented their findings Monday at the American Chemical Society’s (ACS) Fall 2020 Virtual Meeting & Expo. The team stumbled upon this need for a better, biocompatible interface when they had problems integrating inorganic electronics into the brain.
Searching for Biocompatible Coating – Typical microelectronic materials, such as silicon, gold, stainless steel, or iridium, can cause scarring when integrated into biological tissue. In the case of the brain or muscle tissue, this scar can disrupt the movement of electrical signals.
Instead of removing these materials altogether, Martin and colleagues hypothesize that designing a biocompatible coating to go over these devices will give them the best of both worlds.
After experimenting on a number of materials, the team encountered an unlikely hero.
“We started looking at organic electronic materials such as conjugated polymers that were used in non-biological devices,” Martin explains. “We found a chemically stable sample that was sold commercially as an antistatic coating for electronic displays.”
The polymeric coating is technically called poly (3,4-ethylenedioxythiophene), as PEDOT. It is both electrically and ionically active, which the authors explain helps to reduce its impedance (aka its resistance to flowing electric charge) by three to four orders of magnitude compared to electronics without this coating.
“The ability to do the polymerization in a controlled way in a living organism would be fascinating.”
Thanks to its low impedance, this coating increases both the signal strength and battery life of these devices.
In addition to these basic improvements, the authors say that these polymers can also be adapted to add specific functional properties. Researchers can effectively add any peptides, antibodies, or even DNA they want to these modified PEDOTs, Martin explains.
“Name your favorite biomolecule, and you can basically make a PEDOT movie that has whatever biofunctional group you might be interested in,” he says.
Martin and his colleagues test this property by including in the film an antibody that is capable of detecting when a particular blood fish hormone is captured by a tumor.
What comes next – A feature like this could be used to detect the early stages of certain cancers. Martin says his research team has pursued this kind of functionality for the the past twenty years.
In addition to diagnostic use, Martin says Inverse there is also interest in how a polymer coating like this can be used in brain-machine interfaces and even in the incorporation of AI into the human brain. While futuristic, Terminator-like cyborgs are still within the realm of science fiction, Martin says this field of research is evolving rapidly.
“In real life, we’ve seen hot people who can control movements on a computer screen and prosthetic arms with their brains,” says Martin. “Recently, a number of major players such as Glaxo Smith Kline and Elural Musk’s Neuralink have entered the game; the technology has now evolved rapidly and it is clear that there will be some notable future developments.”
Regarding this research, Martin says that her next steps will be to better understand how to tune the behavior of these polymers and then (eventually) to incorporate them into living organisms.
“The ability to do the polymerization in a controlled way in a living organism would be fascinating.”
Abstract: We investigated the design, synthesis and characterization of conjugated polymers for integration of bioelectronic devices with living tissue. These devices are under development for a variety of applications that require long-term electrical communication and interface between electronically actively developed devices and soft electrolytic biological systems. Specific examples include microfabricated neural electrodes, bionic prosthetics, and cardiac cardiac devices. We have developed a variety of functionalized poly (alkoxythiophenes) that make it possible to significantly improve the electronic, mechanical and biological properties of these materials. We will discuss the use of electrochemical deposition methods, combined with a variety of physical and characterization techniques, that have enabled us to understand the relationship between chemical structure, morphology, and macroscopic properties of these polymers. These studies have inspired the design of new molecular structures for improved performance. Most recently, we have directly controlled the electrodeposition process using low dose liquid cell transmission electron microscopy.
