Surface Tension-Guided Drop-and-Spread Inkjet Printing for Additive Fabrication of CNT Field-Effect Transistor Biosensors

Carbon nanotube field-effect transistors (CNT FETs) are highly regarded in nanoelectronics for their superior electrical properties, yet their broader adoption in nanotechnology is hindered by challenges in scalable fabrication. These challenges are primarily related to controlling nanotube density and achieving consistent alignment at electrode junctions for large-scale production. Here, we present a novel in-place inkjet printing technique to construct CNT FETs, ensuring controlled numbers of connected CNTs. We print a series of pico-liter droplets of CNT ink onto prepatterned electrode arrays over a 4-in. silicon wafer, promoting additive device manufacturing without supplementary lithographic steps. Our technique leverages surface tension-driven flow, guiding droplet spread along electrodes, preventing unwanted CNT networks. This approach enhances manufacturing throughput and device yield and efficiently connects an individualized CNT array to electrodes with less than 10 tubes per device. Moreover, we demonstrate biosensing application by functionalizing devices with DNA aptamers, achieving serotonin detection at thresholds as low as 42 pM. This method establishes cost-efficient and simple micromanufacturing protocols essential for the mass production of CNT FET arrays, particularly beneficial for high-throughput bioassays.