[8a-A410-1~8] 3.7 Laser processing

[8a-A410-1] Direct writing of thermoelectric couples on polymer substrates using femtosecond laser reductive sintering of CuO/NiO mixed nanoparticles

〇Mizue Mizoshiri¹, Junpei Sakurai¹, Seiichi Hata¹ (1.Nagoya Univ.)

Keywords:femtosecond laser, microfabrication, reductive sintering

Cu-Ni-based micropatterns were fabricated on polyethylene naphthalate (PEN) using femtosecond laser reductive sintering of CuO/NiO mixed nanoparticles (NPs). CuO NPs, NiO NPs, ethylene glycol, and polyvinylpyrrolidone were mixed using ultrasonic waves. The femtosecond laser pulses (wavelength: 780 nm, pulse duration: 120 fs, repetition frequency: 80 MHz) were focused using an objective lens with a numerical aperture of 0.80 onto the CuO/NiO NP solution film coated on PEN films, following that the samples were scanned using xyz mechanical stages. When the pulse energy were 0.22 nJ to 0.62 nJ, and the laser scanning speed was 20 mm/s, Cu-Ni composite micropatterns were formed. In contrast, Cu₂O composite micropatterns were formed at the scanning speed of 1 mm/s. These results indicate that Cu₂O was generated by reoxidization of reduced Cu, Ni, and Cu-Ni. We demonstrated the fabrication of the thermoelectric couple on the PEN film using the different amounts of Cu-Ni generations. The thermoelectric elements on the thermoelectric couple were formed at the pulse energy of 0.33 nJ and 0.62 nJ, respectively, and at the scanning speed of 20 mm/s. The generation voltage of 5.3 µV/K was obtained at the temperature difference between the hot and cold sides of the thermoelectric couple of 36K.