Freestanding Aligned Carbon Nanotube FETs for Active Single-Molecule Biosensing

High-throughput single-molecule analysis is an important enabler for next-generation omics, including genomics and proteomics. However, reliable electronic detection of individual biomolecules with high signal-to-noise ratio and compatibility with semiconductor manufacturing remains a major challenge.

Carbon nanotube (CNT) field-effect transistors offer exceptional potential for biosensing because of their atomically thin body and high electrostatic sensitivity. At imec, aligned CNT (ACNT) bioFETs fabricated using wafer-scale, solution-based assembly have demonstrated strong electrical performance and promising biosensing results [1,2]. Unlike conventional single-tube devices, this technology provides a path toward scalable and manufacturable biosensing platforms.

This PhD will explore a new class of freestanding aligned CNT bioFETs. Suspending the CNT channel above the substrate can reduce dielectric screening, substrate-induced charge fluctuations, and trap-related noise. This is expected to strengthen the interaction between biomolecules and the CNT channel, improving sensitivity and signal-to-noise ratio toward the detection of individual molecular events.

Beyond conventional diffusion-driven biosensing, the project will investigate active control of biomolecule interactions at the CNT sensing interface. Novel device architectures and electrostatic approaches will be developed to localize, capture, concentrate, or modulate biomolecules near the freestanding CNT channel. Increasing the interaction time could improve detection fidelity and enable the observation of transient molecular processes.

The research combines nanofabrication, liquid-gated electrical characterization, biosensing experiments, and multiscale modeling. The goal is to establish a manufacturable and BEOL-compatible CNT biosensing platform for single-molecule analysis, opening pathways toward future DNA and protein characterization technologies.

Research Objectives

• Evaluate the impact of substrate decoupling on noise, sensitivity, and device stability.
• Quantify the signal-to-noise improvement enabled by freestanding CNT channels.
• Develop electrostatic and device-based methods to control and localize biomolecules near the sensing channel.
• Study CNT-molecule interactions through experiments and multiscale simulations.
• Demonstrate sensitive electronic detection of individual molecular events.
• Assess the platform’s potential for BEOL-compatible omics applications.

Promotor: Pol Van Dorpe
Co-promotors: Lijun Liu and Tim Stakenborg
Daily advisor: Lijun Liu

Figure: Concept of an aligned CNT bioFET

References

[1] L. Liu et al., “Aligned Carbon Nanotube BioFETs: Toward High-Throughput Single-Molecule Sensing,” 2025 IEEE International Electron Devices Meeting (IEDM), San Francisco, 2025, pp. 1–4. DOI: 10.1109/IEDM50572.2025.11353657.

[2] “Towards scalable single-molecule biosensing using carbon nanotube FETs,” imec.
https://www.imec-int.com/en/articles/towards-scalable-single-molecule-biosensing-using-carbon-nanotube-fets