Femtosecond laser-reductive sintering of copper(II)-oxide nanoparticles to produce high-performance micro-heating-structures for future lab-on-chip systems

Reductive laser sintering using a femtosecond laser and copper(II) oxide nanoparticle precursor is a flexible, vacuum-free and maskless technology for the selective metallization of a variety of materials. We use this technology to fabricate high-resolution micro heating structures on cycloolefin copolymer. The surface resistance is measured using a 4-point method and the morphology is characterized using microscope images. The investigation reveals that scan speeds ranging from 60 to 200 mm/s result in the production of homogeneous Cu surfaces, with surface resistances below 100 mΩ/sq. The optimum value of 66 mΩ/sq is achieved at 120 mm/s. Simple heating structures in the form of meander-shaped conductor tracks are produced. Furthermore, current-voltage characteristics are recorded to ascertain the current carrying capacity of the respective manufacturing parameters. The average temperature of the heating structures is determined and compared using a thermal imaging camera. The performance of the heaters is adjusted so that surface temperatures of over 100 °C can be achieved at metallization rates of 2.75 mm/s² . This constitutes the fundamental basis for the utilization of this technology in prospective lab-on-chip applications.