In a new study published in Advanced Materials, scientists at Washington State University and Lawrence Berkeley National Laboratory identified a mechanism to accelerate the movement of ions in mixed organic ion-electronic conductors by more than ten times.
Record ion speeds are achieved in organic conductors where local molecules can attract or repel ions from nanochannels that act as ion superhighways. Image Credit: Second Bay Studios.
Nanoscience has smashed a speed record, potentially leading to many new advancements, such as enhanced battery charging, biosensing, soft robotics, and neuromorphic computing.
These conductors combine the benefits of ion signaling utilized in many biological systems, including the human body, with electron signaling used in computers.
The new technique accelerates ion movement in these conductors by utilizing molecules that attract and concentrate ions into a distinct nanochannel, resulting in a form of tiny “ion superhighway.”
Being able to control these signals that life uses all the time in a way that we’ve never been able to do is pretty powerful. This acceleration could also have benefits for energy storage, which could be a big impact.
Brian Collins, Study Senior Author and Physicist, Washington State University
These conductors have a lot of potential because they allow for the simultaneous movement of ions and electrons, which is essential for battery charging and energy storage. They also fuel systems that mix biological and electrical mechanisms, such as neuromorphic computing, which aims to replicate thought patterns in the human brain and nervous system.
However, how these conductors coordinate the flow of ions and electrons is not well known. Collins and his colleagues discovered that ions traveled slowly within the conductor as part of their research for this study. Due to their synchronized movement, the slow ion mobility reduced the electrical current.
Collins added, “We found that the ions that were flowing all right in the conductor, but they had to go through this matrix, like a rat’s nest of pipelines for electrons to flow. That was slowing down the ions.”
The researchers designed a straight nanometer-sized conduit for the ions to address this issue. Then, they had to draw the ions to it. They relied on biology to accomplish this. All living cells, including those in the human body, employ ion channels to transfer compounds in and out of them, therefore Collins' team used a cell-like mechanism: molecules that like or dislike water.
First, Collins’ team lined the channel with water-loving hydrophilic molecules that attracted ions in water, generally known as electrolytes. The ions then traveled swiftly across the channel, more than ten times faster than through water alone. The migration of ions established a new world record for ion speed in any material to be documented.
On the other hand, ions avoided the channel and were compelled to pass through the slower “rat’s nest” when the researchers lined it with hydrophobic, water-repelling molecules.
Collins’ team discovered that chemical processes might reverse the molecules’ attraction to the electrolyte. This would open and stop the ion superhighway like biological systems regulating access via cell walls.
As part of their experiments, the scientists developed a sensor that could swiftly detect a chemical reaction near the channel by opening or closing the ion superhighway, resulting in an electrical pulse that a computer could read.
Collins added that these nanoscale detection capabilities could aid in recognizing pollution in the environment or neurons activating the body and brain, among other potential applications.
“The next step is really to learn all the fundamental mechanisms of how to control this ion movement and bring this new phenomenon to technology in a variety of ways,” Collins further added.
The National Science Foundation provided funding for this study. In addition to Collins, researchers on the study include first author Tamanna Khan, co-authors Thomas Ferron and Awwad Alotaibi of WSU, and Terry McAfee of the Lawrence Berkeley National Laboratory.