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

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−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−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.