Complementary Metal-Oxide-Semiconductor Integrated Carbon Nanotube Arrays: Toward Wide-Bandwidth Single-Molecule Sensing Systems

Abstract

There is strong interest in realizing genomic molecular diagnostic platforms that are label-free, electronic, and single-molecule. One attractive transducer for such efforts is the single-molecule field-effect transistor (smFET), capable of detecting a single electronic charge and realized with a point-functionalized exposed-gate one-dimensional carbon nanotube field-effect device. In this work, smFETs are integrated directly onto a custom complementary metal-oxide-semiconductor (CMOS) chip, resulting in an array of up to 6000 devices delivering a measurement bandwidth of 1-MHz. In a first exploitation of these high-bandwidth measurement capabilities, point functionalization through electrochemical oxidation of the devices is observed with microsecond temporal resolution, revealing complex reaction pathways with resolvable scattering signatures. High-rate random telegraph noise is detected in certain oxidized devices, further illustrating the measurement capabilities of the platform.

Dielectrophoresis‐Assisted Integration of 1024 Carbon Nanotube Sensors into a CMOS Microsystem

“…Despite promising demonstrations of the integration of CNT devices into CMOS systems, [14][15][16] In this study, we developed an individually addressable array of 1024 CNT electronic nanosensors, each consisting of only one single or very few CNTs as sensing element. We focused on the development of a reliable fabrication process based on the floating-electrode DEP method to directly integrate the CNT devices into a CMOS system without the need to transfer them.…”

“…Additionally, the integration of an array of sensors with differently functionalized devices or graded sensitivity will offer the possibility to multiplex sensor signals or to achieve a larger dynamic range. The use of an array will also offer the possibility to detect and select devices that have been functionalized through low-yield techniques, such as point functionalization.[11] Finally, a dense spatial integration of many sensors reduces the detection volume and external interference and even allows for spatially resolved detection of low-concentration analytes.[12] The most suitable way for monolithic integration of multiple nanoscale devices in arrays is the use of complementary-metal-oxide-semiconductor (CMOS) technology, as it enables the direct integration of the transducers with readout and amplification electronics in a dedicated microsystem.[13] However, a CMOS approach also introduces restrictions in the choice of materials and fabrication process steps (e.g., temperature limitations), as CMOS compatibility has to be ensured.Despite promising demonstrations of the integration of CNT devices into CMOS systems, [14][15][16] In this study, we developed an individually addressable array of 1024 CNT electronic nanosensors, each consisting of only one single or very few CNTs as sensing element. We focused on the development of a reliable fabrication process based on the floating-electrode DEP method to directly integrate the CNT devices into a CMOS system without the need to transfer them.…”

“…Despite promising demonstrations of the integration of CNT devices into CMOS systems, [14][15][16] methods to reliably and reproducibly integrate CNTs into very-large-scale integration (VLSI) technologies are still lacking. Local catalytic growth of high structural quality CNTs requires high temperatures, and is, therefore, not compatible with CMOSbased substrates.…”

“…However, the use of this method can entail misalignment issues and a reduction in the yield of functional devices. [16] Another approach is the CNT assembly from a suspension (top-down). Its main advantage compared to local-catalytic-growth techniques is the possibility to functionalize or sort the CNTs before integration.…”

“…As the CNTs used for this study have not been oxidized or chemically modified, the CNT conductance exhibited a relatively low sensitivity to pH, as has been previously reported. [16] The large variation in the response to the pH change can be, again, attributed to the spread in the CNT properties. The flexibility of the presented array system in sensor selection, along with the large number of available sensor devices can help to overcome the issue of a large spread in sensor properties.…”