Unlocking the Potential of Carbon Nanotube Field Emitters: A Glimpse into MIT's Revolutionary Research

In the field of printed electronics, researchers are constantly pushing boundaries to discover novel applications for emerging materials and technologies. The Massachusetts Institute of Technology’s (MIT) latest research on carbon nanotube field emissions will have lasting impacts in this field, offering vital insights into properties of this material and opening up the opportunity for a wider discussion on its use cases. We're going to synopsize those findings for you; this is a must-read for researchers in printed electronics.

Let's start with the basics.

‍What are carbon nanotubes?

Colloquially called buckytubes, carbon nanotubes (CNTs) are a hollow, cylindrical structure with a diameter in the nanometer range. Their versatility is what makes them so attractive for research. Their structure can adjust slightly to allow for greater functionalization (by slightly shifting the bonded carbon hexagons) and they have great electronegativity, meaning that they have an easy time bonding with other materials. Their cylindrical structure lends them the ability, via ease of covalent bonding, to combine with other materials in order to augment and enhance them. Their predecessors, buckyballs, did not share the same depth of functionality due to the limits of the ball shape.

The power of carbon nanotubes (CNTs)

Carbon nanotubes have emerged as a significant player in the realm of nanotechnology, owing to their remarkable electrical, thermal, and mechanical properties. Composed of carbon atoms in a cylindrical structure, CNTs are at the forefront of innovations in nanotechnology, enabling advancements in fields such as nanoelectronics, energy storage, and sensing. In this context, space propulsion is a key part of MIT’s research.

MIT's pioneering research

Researchers at MIT’s Velasquez Group have delved into the intricate world of carbon nanotube field emissions, exploring the previously uncharted territories of their potential. Their investigations have focused on understanding the intrinsic properties and behaviors of carbon nanotubes (CNTs) when exposed to external electric fields. Advanced experimentation and comprehensive analysis have enabled the researchers to gain deeper insights into the emission characteristics of CNTs. Their work is shedding light on optimizing the configurations and conditions under which CNTs operate, thereby enhancing their performance and expanding their potential applications in printed electronics.

Precision and control: Leveraging NOVA in research

The Velasquez Group employed NOVA, a modular dispensing platform which utilizes advanced direct-ink writing technology to print detailed structures with extreme precision.

Concentric spirals of copper and CNT ink were printed with a minimal 15 µm variation between them. 

This precision is extraordinary and is not commonly achievable with cleanroom equipment available today. Providing crucial control over surface mapping, optical alignment, and pressure control, NOVA was key in realizing such unprecedented results.

“With NOVA, we can make devices and align them to sub 10 micron precision, which is essential to everything that we do. If we have a 20 micron deviation, our devices explode. So you know, we need a lot of precision, we need to have tuned materials, and NOVA enables both of those.”

- Alex Kashkin, Graduate Researcher, Velásquez Group at MIT

Groundbreaking findings: Emission mechanisms and properties

The study provides a profound understanding of the emission mechanisms of carbon nanotubes, emphasizing the significance of field enhancement factor (FEF) and emission areas. Researchers have discovered that the emission currents of CNTs are highly dependent on the geometric configuration and alignment of the nanotubes, as well as the applied electric field. By manipulating these variables, it's possible to optimize the emission properties of CNTs to suit various applications in printed electronics.

One of the key highlights of the research is the revelation that the emission currents are highly localized, occurring predominantly at the tips of the nanotubes, which has crucial implications for designing efficient emission sources. This understanding is pivotal for harnessing the full potential of CNTs in developing advanced electronic devices, sensors, and other nanotechnology applications.

Possible real-world applications

The exploration of carbon nanotube field emitters is just the tip of the iceberg. MIT's work is opening up new avenues for research and development in printed electronics. We're optimistic about harnessing the wide range of capabilities that CNTs exhibit to help transform the landscape of nanotechnology and printed electronics.

‍Medical and scientific instruments: The devices could prove invaluable in miniaturized mass spectrometers, and even in crafting compact x-ray generators.

‍Relaxed vacuum needs: The compatibility with low-vacuum environments, especially at the 10 mTorr level, synchronizes perfectly with the industry’s move towards easing vacuum preconditions for compact instruments.

‍Radiography and materials analysis: Envision a handheld x-ray source, adept at material analysis through fluorescent spectroscopy. With the required currents being significantly lesser than the bias voltages essential for x-ray production, the feasibility is undeniable.

‍Nanosatellite electric propulsion: The CNT fully-printed electron sources can be the go-to for neutralizers in pico and nanosatellite electric propulsion systems. Given their resilience against oxygen traces in low-Earth orbit (LEO), they could find a role in a plethora of nanosatellite missions, ranging from Earth surveillance and communication to weather prediction.

Closing thoughts

MIT’s in-depth research on carbon nanotube field emissions is helping to part the veil on the potential of CNTs in printed electronics. The findings of this study are pivotal for fostering advancements and innovations in nanotechnology. Voltera is proud to play a critical role in unlocking research opportunities, with tools like NOVA enabling research advancements through novel printed electronics technologies. 

Our goal has always been to empower scientists and researchers to explore new possibilities, promising a future where the applications and implications of printed electronics are bound only by the limits of human imagination. By bridging the gap between research and real-world applications, we are stepping into a future with potential for groundbreaking discoveries and developments that could impact daily life from the clothes we wear, to revolutionary medical treatments, and the exploration and understanding of space.

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