Controlled Solvent-Free Formation of Embedded PDMS-Derived Carbon Nanodomains with Tunable Fluorescence Using Selective Laser Ablation with A Low-Power CD Laser

Abstract

We present a study of the application of a single-step and solvent-free laser-based strategy to control the formation of polymer-derived fluorescent carbon nanodomains embedded in poly-dimethylsiloxane (PDMS) microchannels. A low-power, laser-induced microplasma was used to produce a localised combustion of a PDMS surface and confine nanocarbon byproducts within the exposed microregions. Patterns with on-demand geometries were achieved under dry environmental conditions thanks to a low-cost 3-axis CD-DVD platform motorised in a selective laser ablation fashion. The high temperature required for combustion of PDMS was achieved locally by strongly focusing the laser spot on the desired areas, and the need for high-power laser was bypassed by coating the surface with an absorbing carbon additive layer, hence making the etching of a transparent material possible. The simple and repeatable fabrication process and the spectroscopic characterisation of resulting fluorescent microregions are reported. In situ Raman and fluorescence spectroscopy were used to identify the nature of the nanoclusters left inside the modified areas and their fluorescence spectra as a function of excitation wavelength. Interestingly, the carbon nanodomains left inside the etched micropatterns showed a strong dependency on the additive materials and laser energy that were used to achieve the incandescence and etch microchannels on the surface of the polymer. This dependence on the lasing conditions indicates that our cost-effective laser ablation technique may be used to tune the nature of the polymer-derived nanocarbons, useful for photonics applications in transparent silicones in a rapid-prototyping fashion.

3D printing with light: towards additive manufacturing of soft, electroactive structures

“…8 Graphitic nanocrystals and multi-walled carbon nanotubes have been identified as products of laser-induced combustion and the composition of these products is dependent on laser intensity and other process parameters. 9,10 Our own experiments show that the residue from laser-induced combustion of silicone rubber is indeed electrically conductive. We therefore propose the use of laser scribing as a method to produce electrically conductive patterns on the surface of deposited silicone elastomer during the 3D printing process via chemical conversion of the silicone material.…”

“…11 In the works by Hautefeuille et al [9][10][11] , carbon particles were applied to the surface or incorporated in the silicone elastomer to absorb the laser light and locally heat the elastomer to cause combustion. We found that laser induced combustion of the UV-curable silicone used in our 3D printing process is possible without incorporation of carbon particles using a 250 mW, 405 nm violet diode laser.…”

“…The width, depth and composition of the combustion residue has been found to vary with laser power density and exposure time. 10 In our experiments, laser power was kept at maximum (250 mW) and only laser speed was varied. We found that laser scribing of all three UV-curable composites was more reliable and started occurring at higher scan speed of the laser, around 600 mm/min.…”

Progress on the Use of Commercial Digital Optical Disc Units for Low-Power Laser Micromachining in Biomedical Applications

“…As mentioned, absorbing nanocarbon materials are used in order to allow the subtractive manufacturing process to happen. The ionization process that etches the sample can be achieved with several nanocarbon types and it has been found that different allotropic forms may yield different resolutions and etching processes [ 17 ]. In this work, we report the characterization and progress made with carbon nanopowder (633100, Sigma-Aldrich, St. Louis, MO, USA).…”

Progress on the Use of Commercial Digital Optical Disc Units for Low-Power Laser Micromachining in Biomedical Applications

“…As mentioned, absorbing nanocarbon materials are used in order to allow the subtractive manufacturing process to happen. The ionization process that etches the sample can be achieved with several nanocarbon types and it has been found that different allotropic forms may yield different resolutions and etching processes [17]. In this work, we report the characterization and progress made with carbon nanopowder (633100, Sigma Aldrich).…”