Ultra-short pulsed laser PDMS thin-layer separation and micro-fabrication

摘要

Thin-layer separation and micro-fabrication of poly(dimethylsiloxane) (PDMS) polymers are conducted via an ultra-short pulsed laser having a pulse width of 900 fs and lasing at an infrared wavelength of 1552 nm. The plasma-mediated ablation threshold of the PDMS is analyzed as 4.6 J cm{sup}(-2) for single pulse irradiation. The threshold reduces with increasing pulses due to the accumulation effect, and the incubation factor is obtained as 0.52. The influences of two key factors - pulse overlap rate and irradiation pulse energy - on the ablation line width, internal ablation interface depth and ablation surface quality are scrutinized. To achieve quality separation and fabrication without visible thermal damage, a proper pulse overlap rate range of 1-2 pulses μm{sup}(-1) is found with a modest irradiation pulse energy range of 1-1.5 μJ. Complete separation of thin PDMS layers of 20 μm thickness is realized. The separated thin layer is uniform, having a thickness fluctuation of ±1 μm. A multi-width micro-channel interconnected network is fabricated, and the SEM images show that the ablation surface roughness is close to the depth of focus.