Speaker
Description
Electrolyte-gated organic transistors (EGOTs) are highly sensitive biosensing platforms whose electrical response is governed by ionic transport and interfacial processes occurring within the electrolyte. In this work, we integrate EGOT devices with a microfluidic cell [1] to systematically investigate how controlled mass transport, diffusion, and interfacial self-assembly influence gate functionalization and transistor performance. The microfluidic architecture enables precise manipulation of electrolyte composition and flow conditions, decoupling diffusion-driven phenomena from surface-limited reactions at the gate electrode.
A microfluidic H-mixer is aligned with arrays of EGOT gate electrodes to generate stable diffusive interfaces between parallel streams. This configuration produces a well-defined longitudinal concentration gradient along the main channel, which is exploited to modulate the local kinetics of self-assembled monolayer (SAM) formation on adjacent gate electrodes. Using short-chain alkanethiols (3-mercapto-1-propanol, 6-mercapto-1-hexanol, and 8-mercapto-1-octanol) under flow rates between 2 and 50 µL·min⁻¹, we correlate microfluidic transport regimes with electrical readout. The drain–source current systematically decreases along the axial direction of the microchannel, reflecting spatially varying surface coverage and interfacial capacitance.
For short-chain thiols, the current evolution indicates diffusion-limited surface reactions governed by the microfluidic concentration gradient. In contrast, longer-chain thiols yield gate responses that are largely insensitive to axial position, consistent with slower surface diffusion and the formation of more compact, energetically stable SAMs. These results demonstrate that microfluidic control enables reproducible, position-resolved functionalization of transistor gates, allowing the construction of dose–response curves when antibody is streamed along amine terminated functionalization.
Beyond surface assembly, the platform has been further tested for nucleic acid miRNA detection. The sensing mechanism relies on competitive hybridization between solution-phase probe–target complexes and surface-bound probes at the gate electrode, enabling discrimination of oligonucleotide sequences [2] differing by point mutations or deletions. Overall, the microfluidic–EGOT integration provides a versatile framework for controlling interfacial chemistry, improving biosensing reproducibility, and probing transport-limited processes in electrolyte-gated devices.
- Saygin, G. D.; Greco, P.; Selvaraj, M.; Di Lauro, M.; Murgia, M.; Bianchi, M.; Fadiga, L.; Biscarini, F. Concentration Gradients Probed in Microfluidics by Gate-Array Electrolyte Organic Transistor. Sensors and Actuators B: Chemical 404, 135185 (2024). .
- Selvaraj, M.; Greco, P.; Sensi, M.; Saygin, G. D.; Bellassai, N.; D’Agata, R.; Spoto, G.; Biscarini, F. Label Free Detection of miRNA-21 with Electrolyte Gated Organic Field Effect Transistors (EGOFETs). Biosensors and Bioelectronics, 182, 113144, (2021)