24October2017

Nano-Micro Letters

Laser-Assisted Reduction of Highly Conductive Circuits based on Copper Nitrate for Flexible Printed Sensors

Shi Bai1, Shigang Zhang2, Weiping Zhou1, Delong Ma1, Ying Ma1, Pooran Joshi3, Anming Hu1,4,*

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Nano-Micro Lett. (2017) 9: 42

First Online: 09 February 2017 (Article)

DOI:10.1007/s40820-017-0139-3

*Corresponding author. E-mail: anminghu@bjut.edu.cn

 

Abstract

 


Fig. 1 a Schematic of the experimental setup for laser direct writing. The laser beam is directed at a collimator. Afterwards the beam is reflected by a mirror and focused by a microscope objective (NA = 0.3). The translation stage enables the accurate and repeatable positioning of the substrate in two dimensions, with an overall accuracy of about 500 nm. b Schematic illustration of the fabrication of the flexible sensor based on copper electrode: (I) Oxygen plasma etching of the surface of the glass, (II) laser writing of copper salt, (III) coating of PDMS onto a reduced copper electrode, (IV) curing of the PDMS covered substrate, (V) peeling off the PDMS strip from the substrate, (VI) overlay of the PDMS on a target substrate. c Photograph of copper electrode on PDMS substrate. d Spider and zigzag electrodes on PET substrate

Stretchable electronic sensing devices are defining the path toward wearable electronics. High performance flexible strain sensors attached on clothing or human skin are required for potential applications in the entertainment, health monitoring, and medical care sectors. In this work, conducting copper electrodes were fabricated on polydimethylsiloxane as sensitive stretchable microsensors by integrating laser direct writing and transfer printing approaches. The copper electrode was reduced from copper salt using laser writing rather than the general approach of printing with pre-synthesized copper or copper oxide nanoparticles. An electrical resistivity of 96 μΩ cm was achieved on 40 μm-thick Cu electrodes on flexible substrates. The motion sensing functionality successfully demonstrated a high sensitivity and mechanical robustness. This in-situ fabrication method leads to a path toward electronic devices on flexible substrates.


 

Keywords

Laser direct writing; Copper circuit; Stretchable sensor; Laser reduction

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