Microfluidic Channel Fabrication Process Utilizing Nd:YVO_4 Laser-Melting Technique

A simple and repeatable method is proposed for fabricating microfluidic channels on polydimethylsiloxane (PDMS) substrates. In the proposed approach, ridge structures with the required microchannel dimensions are formed on the surface of a borosilicate glass substrate by means of a laser-induced melting process. The patterned substrate is then used as a mold to transfer the microchannel structures to a PDMS layer. Finally, the PDMS layer is aligned with a glass cover plate and is sealed using an oxygen plasma treatment process. The proposed patterning technique is a maskless method, and is thus cheaper and more straightforward than conventional lithography techniques. Moreover, unlike direct laser ablation methods, the proposed method requires significantly less input energy, and therefore minimizes thermal effects such as substrate cracking and distortion. The feasibility of the proposed fabrication method is demonstrated by measuring the capillary filling speed of human blood plasma in microfluidic channels with cross-section sizes of 19.5\times2.5, 17.0\times1.6, and 7.6\times1.1 μm^2 (width\timesheight), respectively, and temperatures of 4^\circ\!C, 25^\circ\!C and 37^\circ\!C. It is shown that the filling speed reduces with a reducing channel cross-section size, a lower operating temperature, and an increased filling length.