Bright IDEAS Award: Nanoparticles On demand Via multiphoton Absorption (NOVA): the practical nanoparticle-making machine.

Lead Research Organisation: University of Southampton
Department Name: Optoelectronics Research Centre

Abstract

Making nanoparticles, and printing of materials with nanoscale sizes is an important research topic these days. From a materials manufacturing point of view however, the obvious questions are how to make nanoscale objects, how to optimize their size and size distribution, their exact shape and so on. What is needed is a processing technique that will allow nanoscale materials to be generated from starting precursor liquids or gases. Using the process of multiphoton absorption of high power pulsed laser sources, such a technique should now be possible. Multiphoton absorption occurs when a high peak power laser source is focused down to a small spot size, producing a local photon density that can be incredibly high. Within the focal region, materials such as liquids or a gas that do not absorb at the fundamental laser wavelength can now do so by absorbing several photons at once. If you use multiple laser sources, all focused down to equally small spot sizes, and make the focal regions overlap, then absorption will occur only within this tiny interaction volume, a 3-d pixel or voxel. The liquid or gas can then decompose, releasing elements such as metals into essentially 'free space'. Multiphoton absorption relies on local brightness (photon density per unit time) of the laser sources, and so the technique should allow materials synthesis within extremely small volumes, and specifically much smaller than the wavelength of the incident laser light. It is within this voxel that the nanoparticles you want are born. Changing parameters such as laser beam overlap, the laser wavelength, or input light polarization generates a fantastically versatile toolbox for nanoparticle generation. Spherical, ellipsoid, hollow, strings or springs, many such shapes should be possible. If you simultaneously flow two different materials through the interaction region, you can make nano-alloys, coated nanoparticles, and more.If the precursor materials flow over a substrate, then local decomposition via multiphoton absorption will lead to the printing of small dots and lines of materials such as metals, semiconductors and more. This is the second part of the programme, and the intention is to follow both routes of making 'free' nanoparticles as well as printing of nanoscale objects. Nobody has so far attempted this 3-d multiphoton route to materials manufacturing. Many groups have successfully written structures via single beam, multiphoton techniques, in liquid monomers for example, and have produced exotic miniature sculptures such as bulls, statues and spiders, but only in polymers. If successful, this radically new multi-beam approach will lead to controllable nanoparticles on demand, and 3-d nano-sculpting in whatever material you can produce from decomposition of the original liquid or gas precursor.

Planned Impact

On advice from the Big Pitch administrtion, I have copied directly from the original 2 page proposal here: Materials manufacturing and technology drives everything. If you haven't got the material you need, then you are effectively wasting your time. Once you can grow it, where you want it, at a scale length that you specify then this is the time to exploit the technique, and to show all interested parties just what you can now do. Nanoscience in general, and Nanoscience through Engineering to Application are currently technology leaders, and the proposal here is to make a nanoparticle machine, that is the end goal of all nano-technologists. Environmental scientists investigate nanoparticulates due to their potential for both good and ill, and there are large numbers of manufacturers who rely on designer nanoparticles for their livelihood. Pharmacological companies, medical companies, cosmetic producers, and many more nanotechnology-aware end-users should give their eye-teeth for such a machine that can prototype their nano needs with such a short turn-round time. A more detailed and factual Impact Plan is inclued in the attachements list
 
Description The main discovery related to the use of multiple overlapping ultrashort laser pulses (overlapping in both space and time) to induce nonlinear effects in suitable media such as photopolymers. The length of the pulses combined with their high intensity is the key factor in being able to localise laser-induced materials modification
Exploitation Route there are ready applications in laser-based processing in transparent materials, where multiple laser pulses can be arranged to be incident in time and space to induce material changes that can be applied in optical storage, or other high density research directions
Sectors Aerospace, Defence and Marine,Chemicals,Manufacturing, including Industrial Biotechology,Pharmaceuticals and Medical Biotechnology