Generating New Size-Specific Nanoparticles

Nanoparticle generation is notorious for being a clumsy, awkward process that can take months to perfect. This means that research which involves multiple different types of nanoparticles is often held back by the creation of the nanoparticles themselves. To address this problem, VSPARTICLE have developed a new instrument that uses spark ablation to produce particular nanoparticles, of a set size distribution, all in one afternoon.

What are the conventional problems associated with the creation of nanoparticles? How does the VSP-G1 nanoparticle generator avoid these?

The problems faced in nanoparticle production are threefold. The process is time-consuming and it is not interchangeable for different materials, meaning a new method must be used to generate different nanoparticles and, in addition to this, reproducibility is also a big issue.

Because of this, researchers spend years of their Ph.D. on the synthesis of nanoparticles, instead of on the actual application of them. Conventional methods rely on carefully tweaked chemistries, which makes it difficult to tune the size, composition or scale of a synthesis.

Another problem is post-processing – conventional methods provide a powder or suspension as an end product. This is problematic as powders need to be re-dispersed before use, whilst suspensions require the surfactants and solvents to be removed. Both are costly procedures and often involve the risk of worker exposure.

VSPARTICLE aims to provide a complete solution from nanoparticle synthesis to the immobilization of nanoparticles on or into your product. The VSP-G1’s settings can be adjusted without effort, making changes in nanoparticle size and composition trivial and helping in scaling up.

The method used in the VSP-G1 (spark ablation) is easy, fast and reproducible. Because spark ablation is a purely physical process, the fabrication of particles and the integration of them into your device always works in exactly the same way, enabling you to start working on your product without the hassle that comes with conventional production.

A pie chart demonstrating the wide range of application areas of nanoparticles. An interactive copy can be found here.

What materials can the VSP-G1 nanoparticle generator create nanoparticles from?

The VSP-G1 can create nanoparticles from any (semi-)conducting material, allowing researchers to create nanoparticles from 90% of the elements in the periodic table. Furthermore, materials that are normally immiscible on the macroscale can be alloyed on the nanoscale using spark ablation technology. An example of this are Au-Cu particles, created using sparks between an Au and a Cu electrode.

The particles are created in a continuous flow of gas, typically argon or nitrogen. The gas can easily be delivered through post-processing stages, which facilitates size-selection, or modifications such as oxidations.

As particles become larger, they nucleate and form solid particles. The morphology and primary size that is favored during nucleation can easily be tweaked using the VSP-G1.  Depending on your substrate, VSPARTICLE can also provide different solutions to immobilize the produced particles.

How precise is the nanoparticle creation process?

In terms of stability, the standard deviation of the particle size output can be reduced to less than two percent. Particles produced by the spark have a primary particle size, which can be tuned by altering the annealing temperature. Particle size distributions typically have a geometric standard deviation of 1.3-1.4 nm. For specific applications, size distributions of +/- 0.2 nm or better can be achieved.

The VSP-G1 is most precise in the 0-20 nm range. However, with additional equipment, particles can be selected on their size, accurately down to 0.1 nm.

In which fields do you see the VSP-G1 nanoparticle generator making the biggest impact?

There are four fields in which we see a great future for the VSP-G1: microelectronics, catalysis, energy and healthcare.

Compared to printing electronics with conductive inks, using beams of pure nanoparticles to print conductive lines allows for sintering at lower temperatures. The outcome of this is the creation of conducting lines which possess a higher conductivity.

‘Printing’ with a nanoparticle spray can also be achieved for the coating of an entire surface, to produce a porous later that could be used for sending – the porosity of laters produced by the VSP-G1 makes it possible to detect even the lowest amount of gas or biomolecules.

The use of nanoparticles in catalysis is already established, but a reliable method of creating nanoparticle catalysts for size and composition comparisons is not. Differing metal and metal-oxide nanoparticles of various shapes can be easily compared against one another using the VSP-G1 allowing the optimal nanoparticle properties for a particulr catalytic process to be determined. Using the new VSPARTICLE accessory particles can be directly deposited onto an in-situ TEM grid for analysis.

Because nanoparticles have strong applications in the fields of electronics and catalysis it is inevitable that they will influence the production and storage of energy as well.  Nanoparticles are currently being used to improve solar cells absorption of sunlight. A higher absorption of solar enables a higher energy production, during sunny days, nanoparticles enable nano-structured super capacitors to store more energy.

In the healthcare field, scientists working on nanoparticle therapies, such as iron oxide nanoparticles for hyperthermia and enhanced MRI, antibacterial nanosilver or gold nanoparticles for targeted drug delivery are struggling to get FDA approval. This is mostly due to the presence of chemical contaminants in their nanoparticle formulations. By using spark ablation, researchers can produce nanoparticles which are contaminant free, speeding up the approval process and working faster to nanomedicine end-user applications.

Shutterstock |  Andrey VP

What advantages do your nanoparticles provide for the Semiconductor and other patterning industries?

The extremely small size of nanoparticles makes them very sensitive to external stimuli. This sensitivity can be used to develop novel sensors or used as a way to create metallic interconnects using low-temperature processes.

Nanoparticle generators make it possible for a semiconductor manufacturer to have full control over their entire production chain – from nanoparticle generation to the integration of the nanoparticles in the devices they create.

What inspired the team at VSPARTICLE to develop the VSP-G1? Why did you choose to use Spark Ablation?

While we were at the Delft University of Technology, we noticed many people had difficulties in adapting nanoparticle recipes for their need. These were researchers in a multidisciplinary environment, with expertise in fields such as materials for energy conversion and storage, photovoltaics, healthcare and catalysis. We saw researchers spend months to obtain the nanoparticles they required before they could carry on with their research.

In contrast, students in our lab would receive 2-hours of training, and would have nanoparticles of the composition and size they wanted by the end of the day. This is largely due to the flexibility of spark ablation: if we can make the bulk electrode, we can make the nanoparticles. We want to give other people the same possibilities.

Can VSPARTICLE help their customers develop their own nanoparticle production processes tailored to their application?

Using VSPARTICLE spark generators, the need to change the particle production process is taken away. VSPARTICLE means researchers don’t have to worry about particle production and lets them focus on their true application from day one.

By considering the whole process, from nanoparticle production to application and bringing solutions in deposition/integration, VSPARTICLE can speed up research and facilitate industrialization.