Near-infrared femtosecond laser direct writing of microchannel and controlled surface wettability

The application of femtosecond laser in fabricating poly (methyl methacrylate) microchannels and the alteration of wettability by inducing a change in chemical functional groups has already been established and reported in literature. However, studies on the application of femtosecond laser for modification of surface wettability without significant chemical modification, are yet to be reported. The paper reports work on an expedition of femtosecond (Ytterbium-doped fiber) laser ablation working at the near-infrared wavelength (1030 nm) tuning the wettability behavior comprising of hydrophilic and hydrophobic state on the basis of the surface morphology created below the focal beam diameter. The initial part revolves around the investigation of near-infrared femtosecond laser ablation for achieving microcavity and microchannel below the focal beam diameter. The latter part deals with laser surface modification for attaining both hydrophilic and hydrophobic surfaces. The study obtained a high degree of hydrophobicity, with a maximum water contact angle of 129.05 degrees at a laser energy of 40 mu J and pulse laser overlap of 96%. It was also possible to attain a minimum water contact angle of 56.35 degrees using a laser pulse energy of 40 mu J and pulse overlap of 0 %. The reported work avoids surface chemical modification for controlling the wettability.