Fabrication of wearable strain sensor by using a novel hybrid Cu ink composed of bimodal Cu particle ink and Cu-based metal-organic decomposition ink

In this work, bimodal Cu particles have been synthesized by using 2-amino-2-methyl-1-propanol (AMP)-based hybrid capping agent for the first time. A novel hybrid Cu ink is prepared by combining bimodal Cu particles with solvents and Cu-based metal-organic decomposition (MOD) ink composed of Cu(II) formate, AMP and octylamine. The printed Cu patterns (films) by using the hybrid Cu ink show resistivity as low as 60 μΩ•cm after sintering under mid processing conditions (e.g., sintering at 110°C for 20 min in nitrogen atmosphere). The results also show that sintered Cu films of the hybrid Cu ink have good adhesion property on glass, polyimide (PI) and polyethylene terephthalate (PET) substrates, and the flexible Cu circuits on flattening and bending PI or PET substrates play the function well, in terms of easily lighting LEDs (light emitting diodes) in the circuits. Finally, the wearable strain sensor fabricated by using the hybrid Cu ink can also be well used to monitor the movement of human finger. All these results show that the hybrid Cu ink has high potential for application in printed flexible electronics.