Physicists Analyze Organic Electrochemical Transistors for Medical Sensing

The medical and science communities are always seeking new ways to study and monitor organs and common diseases to improve human health and quality of life.  

While there is a seemingly endless need for versatile, low-cost, yet highly sensitive biochemical sensor devices, there are many steps to take between initial research and clinical application.  

At Kent State University, Dr. Björn Lüssem, an associate professor in the College of Arts and Sciences’ Department of Physics, and the graduate students in his laboratory have taken some of those initial steps toward the goal of an application. At the early stages, his group is looking at single sensors and trying to better understand and improve the performance of the transistor component of organic electrochemical transistors-based devices (OECTs), which are microscopic to miniature-sized sensors that can be used to interact with biological tissue.

In their recent article in Nature Communications, titled “Finding the Equilibrium of Organic Electrochemical Transistors”, Lüssem and his graduate students Vikash Kaphle, Ph.D., Pushpa Raj Paudel, Drona Dahal, and Raj Kishen Radha Krishnan unveil their latest analysis on OECTs and their working mechanisms. Kaphle, who researched this topic in his dissertation work, recently earned his doctorate and is now a postdoctoral research associate at the University of Southern Mississippi.

To better understand the origin of current instabilities of OECTs and to quantitatively describe the sensing mechanism, they implemented and validated a 2D numerical simulation to quantify carrier densities and electric fields inside the devices. The project was funded by a National Science Foundation grant and their devices were prepared in the Cleanroom Prototyping Facility of Kent State’s Advanced Materials and Liquid Crystal Institute.

To read the full article, visit:

“These OECTs show a very high performance, in particular a large amplification of small signals,” Lüssem said. “They are mechanically flexible, which is essential for many applications such as wearable sensors.”

Organic electrochemical transistors are an important link between biology and microelectronics. They operate in aqueous environments, are flexible and bio-compatible, and translate ionic into electronic currents. However, there are some challenges for modeling these devices, so Lüssem’s lab group wants to find out how they can improve and add components to the basic transistor to make it more sensitive to certain biomolecules.

“It is still challenging to formulate precise design rules guiding materials development in this field,” Lüssem said. “In our article, we’ve shown that lateral ion currents lead to an accumulation of ions at the drain contact, which significantly alters the transistor behavior, so a better understanding of the interface between the organic semiconductor and the drain electrode is needed.”

The researchers plan to continue to study the working mechanism of the transistors and will try to understand the precise sensing mechanism in more detail. They also plan to develop dedicated sensors that can be used by researchers from Kent State’s Brain Health Research Institute.

To learn more about Dr. Lüssem's research, visit his lab homepage:

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Media Contact:
Jim Maxwell,, 330-672-8028

POSTED: Thursday, May 28, 2020 - 11:43am
UPDATED: Friday, May 29, 2020 - 10:29am
Jim Maxwell