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

Abstract

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.

Stretchable electroadhesion for soft robots

“…For the fabrication, we used a sequential casting method similar to [14] (see Fig. 3a-d) that can be used with a variety of materials and pad designs.…”

Laser-Assisted Printed Flexible Sensors: A Review

“…The use of laser ablation on nanocomposites is also explained by Liu et al [75] in their work on conductive composites developed from CNTs and PDMS. The key advantages in these sensors lie in the high electrical conductivity of the electrodes, flexibility of the sensors, and ability to achieve features in micron levels.…”

Fabrication and Patterning Methods of Flexible Sensors Using Carbon Nanomaterials on Polymers

“…Laser ablation is a technique used to define patterns onto a flexible substrate such as PET. A focused laser delivers high optical energy to the substrate, thereby breaking up the molecular bonds and evaporating the molecules in gaseous form . A conductive CNT/PDMS nanocomposite is then poured into the grooves, and the extra amount is removed by a blade.…”

“…After curing the device is debonded, having conductive CNT/PDMS structures exposed, and b) relief structures on PDMS after debonding, showing a minimum width of 19 μm. Reproduced with permission . Copyright 2012, IOP Publishing Ltd.…”