NanoCube: A Low-Cost, Modular, and High-Performance Embedded System for Adaptive Fabrication and Characterization of Nanogaps

This paper presents an embedded modular system, NanoCube, able to repeatedly fabricate a pair of nanometric ter- minal probes (nanogaps) using the electromigration-induced break junction and capable to characterize them for low-cost molecu- lar electronic devices and biomolecular sensing. NanoCube imple- ments a flexible control loop which predicts both temperature and current and efficiently manages the electrical stimulation applied to ad hoc PCB cartridges, including a silicon chip with gold wire probes to be electromigrated. The modular and flexible system em- beds the core circuits devoted to nanogap fabrication, signal condi- tioning and measurement, and the microprogrammed subsystems. NanoCube runs a real-time Linux operating system, with a fully customizable electromigration algorithm which considers fabrica- tion history to adaptively improve performance. After 250 fabri- cation runs the system is shown to be able to fabricate nanogaps under 3 nm with 29% yield, and with 53% yield if we consider gaps under 10 nm. To validate the system, experiments using the fabricated nanogaps with bonded oligothiophene molecules were run, verifying the theory of molecular conduction.