"Plastic Transistors" Prove Promising for Signal-Boosting Biochemical Signals, On-Site Sensing

Researchers at Northwestern University have come up with a new technology designed to "eavesdrop" on the body in order to detect biochemical signals without having to take blood or saliva samples — boosting sensitivity using "plastic transistors."

“If we could reliably measure biochemical signals in the body, we could incorporate those sensors into wearable technologies or implants that have a small footprint, less burden and don’t require expensive electronics," explains senior author Jonathan Rivnay of the team's goal. "But extracting high-quality signals has remained a challenge. With limited power and space inside the body, you need to find ways to amplify those signals."

Transistors are capable of boosting these signals, but anything which is designed to work in the human body can't be too bulky or require too much power to run. To get around this, the researchers took a traditional aptamer electrode-based sensor and added an amplifying component — creating an electrochemical transistor-based sensor capable of boosting weak signals.

"We combine the power of the transistor for local amplification with the referencing you get from well-established electrochemical methods," explains first author Xudong Ji of the prototype, which includes a built-in thin-firm reference electrode to increase signal stability. "It's the best of both worlds because we’re able to stably measure the aptamer binding and amplify it on site."

The overall aim of the project is to develop a sensor which can detect target biochemical signals within the human body itself, replacing the traditional approach of taking blood or saliva samples and sending them to a lab for time-consuming processing with a point-of-care instantaneous detection system.

Testing shows that could well be possible: the prototype, tuned to detect a common cytokine, proved able to boost signal strength by three to four orders of magnitude over its rivals — and the team believes it should be generalizable to any molecule or chemical, from antibodies and hormones to drugs, providing electrochemical detection methods exist.

"This approach is broadly applicable and doesn’t have a specific use case," Rivnay concludes. "The big vision is to implement our concept into implantable biosensors or wearable devices that can both sense a problem and then respond it."

The team's work has been published in the journal Nature Communications under open-access terms.