Members of the Rivnay lab, Jonathan Rivnay, Xudong Ji and Abhijith Surendran, have contributed to a new paper, Vertical organic electrochemical transistors for complementary circuits.

A transdisciplinary Northwestern University research team has developed a revolutionary transistor that is expected be ideal for lightweight, flexible, high-performance bioelectronics. 

“This exciting new type of transistor allows us to speak the language of both biological systems, which often communicate via ionic signaling, and electronic systems, which communicate with electrons,” Rivnay said. “The ability of the transistors to work very efficiently as ‘mixed conductors’ makes them attractive for bioelectronic diagnostics and therapies.”

Read more about the paper here.

Great group outings this summer:

In June the group went to Hearthstone and Terrace in Chicago for a Terrarium building workshop! Lots more greenery in lab and at home!

A last Harrah to summer: group Kayaking near Starved Rock, followed by a Cookout by the Illinois river.

Postdoc Josh Tropp was named ACS PMSE Future Faculty Fellow: https://pmsedivision.org/pmse-future-faculty/ He received this honor and gave a number of talks at the ACS Fall Meeting in Chicago.

In addition, Josh was named NU Postdoctoral Association’s Postdoc of the month for the month of August 2022: https://sites.northwestern.edu/nupa/postdoc-of-the-month-1/

Congratulations to Graduate Student Rebecca Keate, joint with Guillermo Ameer, on her Rising Stars lecture. See also her SQI interview here (https://sqi.northwestern.edu/news-and-events/news-and-announcements/2022/meet-the-researchers-rebecca-keate.html )

Congratulations to Jonathan Rivnay who was promoted to Full Professor with tenure in the Dept. of Biomedical Engineering, effective Sept 1, 2022.

Our paper “Sources and Mechanism of Degradation in p-Type Thiophene-Based Organic Electrochemical Transistors” was published in ACS Applied Electronic Materials.

https://pubs.acs.org/doi/full/10.1021/acsaelm.1c01171

Most work on OMIEC degradation focuses just on the polymer itself, and maybe the polymer in a particular electrolyte. While this is helpful, it doesn’t tell the whole story…what about device architecture and implementation? What about how you operate/bias the OECT?

If it’s pulsed in a diode-connected manner (G-D shorted) the degradation is much lower than when operated in a 3-terminal OECT or as an electrode (S-D shorted). It’s all about the combo of oxidative and reductive bias stress.

The reaction of dissolved oxygen at the buried Au/OMIEC interface of the drain electrode experiencing reductive potentials produces mobile reactive species that degrade the oxidized OMIEC in the device. This seems to be general across a number of thiophene p-type OMIECs.

This leads to design rules: we can avoid degradation by (1) removing oxygen (not practical for bioelectronics), (2) avoiding reductive potentials via device biasing scheme, (3) replacing Au electrodes with a noncatalytic alternative, or (4) passivating Au electrodes with self-assembled monolayers.

This was a great team effort lead by grad student Emily Schafer, with Ruiheng Wu, Dilara Meli, Josh Tropp and Bryan Paulsen, and of course, with materials from Iain McCulloch and team.

Graduate Student Reem Rashid defended her PhD Thesis Spring 2022. Congratualtions Doctor! She is the lab’s first PhD graduate.

Thanks to the committee: John Rogers, Neha Kamat (NU), and Simone Fabiano (Linkoping)

Our work "A Semiconducting Two‐Dimensional Polymer as an Organic Electrochemical Transistor Active Layer" was published in Advanced Materials. Congratualtions to Reem Rashid for leading this effort with Austin Evans from Will Dichtel's group. This work involved a multi-group collaboration with the Marder, D'Allesandro, and Dichtel's groups.

Typical OMIECs are linear polymers, where defined and controlled microstructure/morphology, and reliable characterization of transport and charging can be elusive. Semiconducting two-dimensional polymers (2DPs) present a new avenue in OMIEC materials development, enabling electronic transport along with precise control of well-defined channels ideal for ion transport/intercalation. In this work we use a recently reported 2DP, TIIP, and patterned at 10 µm resolution as the channel of a transistor. Operating in an aqueous electrolyte, the 2DP-OECT exhibits a device-scale hole mobility of 0.05 cm2 V–1 s–1 and a µC* figure of merit of 1.75 F cm–1 V–1 s–1. 2DP OMIECs thus offer new synthetic degrees of freedom to control OECT performance and may enable additional opportunities such as ion selectivity or improved stability through reduced morphological modulation during device operation.

Grad Student Ruiheng Wu led an opus “Operando Characterization of Organic Mixed Ionic/Electronic Conducting Materials” now out in Chemical Reviews as part of a special issue on “Organic Bioelectronics”. Congrats Ruiheng, Bryan Paulsen, and a special thank you to Micaela Matta (King’s College, London).

This review provides a broad survey of operando techniques used to study OMIECs. In some cases, we highlight techniques that could provide useful insights but have not yet been demonstrated with OMIECs due to barriers to implementation. Micaela also delves into computational approaches that have been applied to OMIECs. It's important to consider these in silico methods in our in situ/operando toolbox working side by side with experimental tools.

Our ongoing collaborative work with Cheng Sun’s lab at Northwestern is out now in Macromolecular Bioscience https://onlinelibrary.wiley.com/doi/full/10.1002/mabi.202200103

“3D-Printed Electroactive Hydrogel Architectures with Sub-100 µm Resolution Promote Myoblast Viability.” Congratulations to Rebecca Keate on leading this effort, as well as Josh Tropp, Anthony Petty, and the Sun group.

Reem has published a new paper which focuses on means to make “back end” electronics more usable in more compact means, which could revolutionize how medicine utilizes bioelectronics in the body.

Congratulations Reem!

Read Northwestern’s press release on the paper here, and read the full study here!

Our lab has received a cooperative agreement with DARPA to develop a wireless, fully implantable ‘living pharmacy’ device that could help regulate human sleep patterns. The project is through DARPA’s BTO (biotechnology office)’s Advanced Acclimation and Protection Tool for Environmental Readiness (ADAPTER) program, meant to address physical challenges of travel, such as jetlag and fatigue.

The device, called NTRAIN (Normalizing Timing of Rhythms Across Internal Networks of Circadian Clocks), would control the body’s circadian clock, reducing the time it takes for a person to recover from disrupted sleep/wake cycles by as much as half the usual time.

The project spans 5 institutions including Northwestern, Rice University, Carnegie Mellon, University of Minnesota, and Blackrock Neurotech.

See coverage on this exciting program at:

·         Northwestern

·         WGN

·         Smithsonian Magazine’s website

Reem Rashid has received two award, one Fulbright grant and one from the American-Scandinavian Foundation (ASF) award. She will use both to travel and study at Linkoping University in Sweden.

Learn more about the ASF here.

Congratulations Reem!

Johnathan Rivnay gave a presentation entitled “Organic Electrochemical Transistors for Bioelectronics” at the 2021 conference.

IEEE is the world’s largest technical professional organization dedicated to advancing technology for the benefit of humanity.

Read the details and learn more about the conference here.

Congratulations Jonathan!

The article, “Mixed Ionic-Electronic Transport in Polymers” was published in July 2019. It was written by Bryan D. Paulsen, Dr. Rivnay, and Simone Fabiano, of the Laboratory of Organic Electronics, Department of Science and Technology, Linköping University in in Norrköping, Sweden.

Read the full article here.

Congratulations, Bryan!

The study, “Regiochemistry-Driven Organic Electrochemical Transistor Performance Enhancement in Ethylene Glycol-Functionalized Polythiophenes,” was a collaboration with the McCulloch group at King Abdulla University of Science and Technology.

Congratulations to Reem, Bryan, and Anthony Petty, a former post-doc of the lab.

Please check it out here!

The review examines the potential applications of organic electrochemical transistors in bioelectronic circuits, which hold potential in fields of printed electronics, bioelectronics, and neuromorphic computing among others.

Read the article here.

Congratulations to Reem, Xudong and Professor Rivnay!

Researchers have developed a brain-like computing device that is capable of learning by association. 

Similar to how famed physiologist Ivan Pavlov conditioned dogs to associate a bell with food, researchers at Northwestern University and the University of Hong Kong successfully conditioned their circuit to associate light with pressure. 

The research was published today (April 30) in the journal Nature Communications. 

Read more about the study here.

Great job, Xudong!

The goal of this annual symposium is to highlight and provide a forum for ~15 early-career emerging leaders who have made significant contributions in their respective fields within polymer materials science and engineering. Example research areas include synthesis, processing, characterization, physics, and engineering of macromolecular materials.

Read more here

The Northwestern Predoctoral Biotechnology Training Program is an interdisciplinary and interdepartmental program that provides select graduate students (Trainees and Cluster members) greater research and training opportunities than those available through the individual departments. It promotes interdisciplinary education in biotechnology, interactions among faculty and students with interests in biotechnology, and provides a substantial exposure of students to industrial biotechnology research.

Congrats, Rebecca!

Read more about the program here