Precision patterning of conductive polymer nanocomposite using a laser-ablated thin film

We introduce a simple, reliable and low-cost microfabrication technique utilizing laser ablation of a thin polymer film to pattern polymer nanocomposite at a high resolution. A conductive composite of poly(dimethylsiloxane) (PDMS) and carbon nanotubes (CNTs) was selected due to their wide use in microelectromechanical systems (MEMS) and unique properties including flexibility and piezoresistivity. To pattern nanocomposite, an excimer laser ablated through a thin polyethylene terephthalate film creating mold patterns. PDMS-CNTs nanocomposite was then filled into the mold with excessive amount removed by a smooth-edged tool. Bulk PDMS was poured atop and cured. After debonding devices with relief patterns of polymer nanocomposite could be readily realized. Fabrication conditions were optimized which led to reliable patterning of various microstructures. Detailed surface profiling revealed excellent pattern authenticity and uniformity. Minimal feature size of patterns reached below 20 µm which indicated a significant improvement from prior reports. Moreover, the presented technique required only a software design to rapidly generate new patterns, thereby eliminating costly hardware such as lithography mask, stamp and clean room. Fabrication time and cost could be consequently reduced—ideal for lab prototyping purposes. Sensor examples are discussed to demonstrate versatile applications of polymer nanocomposite in MEMS.