Microchannels are fabricated in a poly(methyl methacrylate) substrate by nano-joule and micro-joule femtosecond laser pulses. Fabrication of microchannels within the volume of the substrate or etched into the surface can be achieved using focused femtosecond pulses. The size and shape of the microchannels can be controlled by changing the fabrication parameters of speed, focusing objective, the number of fabrication repeats and the delay in-between fabrication repeats. It has been proposed that for nJ pulses diffusion of heat from the focal region to the polymer matrix due to the high repetition rate and repeated exposures results in the formation of microchannels, as compared with direct ionisation of the substrate for µJ pulses. The diffusion of heat through the substrate is a uniform process which has the effect of creating symmetrically shaped channels under nJ pulse intensities. These fabrication methods are expected to have applications in the fabrication of microstructures or microfluidic devices in polymer substrates.
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2006
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