Detect The Undetectable in Wearables and Brain-Machine Interfaces: pM-Level Biomolecular Detection with Fast-Scanned Aptamer-OECT

Biomolecular detection is the next goal for wearable devices. The lower limit of detection (LoD) is a critical metric for wearable biosensors. In this study, we demonstrate that aptamer-based Organic Electrochemical Transistors (OECTs) can detect concentrations in the picomolar range (close to the dissociation constant, K_d) in a fully-integrated wearable context [1], which is not achievable with a standard electrochemical sensor. The high transconductance (g_m) of OECTs allows for a more significant variation in current, making the sensor highly resistant to ambient noise.<br/><br/>Specifically, we observed that a high scanning rate improves LoD to values close to the theoretical limit (K_d) of the aptamers. This improvement is achieved by operating OECTs at optimal high frequency range where the leaking reaction resistance most vibrates with the binding of the molecules [2]. Thus, microscale OECTs are essential for achieving a higher cutoff frequency for rapid scanning purposes.