Femtosecond laser bulk micromachining of microfluid channels in poly(methylmethacrylate)

Internal channels in a polymer are widely used in biotechnology applications such as DNA stretching and in devices such as micrototal analysis systems and lab on a chip systems. For manufacturing prototype devices, femtosecond pulsed laser energy has been used to implement a convenient direct write bulk-machining process in glass. In this technique, the laser beam is focused inside of a transparent material, resulting in the ablation of an internal channel. Initial experiments for internal channel fabrication in a poly(methylmethacrylate) (PMMA) polymer revealed a significant problem with clogging of channels by debris and rough, fractured channel walls. In this article, we describe a new method to fabricate internal channels in PMMA using femtosecond pulsed laser energy and a gas-assisted material removal concept. Relatively smooth channels with a minimum diameter of 2 μm, a maximum diameter of 20 μm, and a maximum length of 10 mm were achieved with this technique.