PCB-MEMS: Fabrication of active microfluidic devices by laser ablation

© 2017 Nova Science Publishers, Inc. This chapter focuses on laser ablation processing of metallic and polymeric thin films used in microelectromechanical systems technology for the fabrication of microfluidic devices with integrated electrodes on printed circuit boards (PCB-MEMS). The fabricated devices has flame retardant (FR)-4 resin as substrate, copper (Cu) as active material and SU-8 polymer as structural material. Cu interdigitated electrodes and a SU-8 microfluidic network are patterned on the FR-4 substrate by a 355 nm diode-pumped Nd: YAG ultraviolet (UV) laser system. The effect of laser power on ablation depth is characterized for Cu films with different roughness as well as for SU-8 films with different percent solids. Likewise, critical dimensions are determined for both materials. The integration of these heterogeneous components into a functional PCB-MEMS device is demonstrated by fabricating a capacitive sensing microstructure for liquid recognition through impedance spectroscopy. The resolution, repeatability and simplicity achieved in this approach, along with the low cost of the involved materials and methods, enable an affordable micromachining technique based on laser ablation with a rapid fabrication-test cycle to develop microelectromechanical structures and active microfluidic devices with potential applications in biosensing, cell culture, drug delivery, transport and sorting of molecules, among others.

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