Flexible Metal Electrodes by Femtosecond Laser-Activated Deposition for Human–Machine Interfaces
Yaqiang Ji, Yuxuan Liao, Haihui Li, Yuhang Cai, Dongliang Fan, Qian Liu, Shubin Huang, Renjie Zhu, Shuai Wang, Hongqiang Wang, Liang Guo
Abstract
Flexible metal electrodes are essential for flexible electronics, where the main challenge is to obtain mask-free patterned metals directly on substrates such as poly(dimethylsiloxane) (PDMS) at low cost. This work highlights a feasible strategy named femtosecond laser-activated metal deposition for electroless deposition of metals (Cu, Ni, Ag, and Au) on PDMS, which is suitable for maskless and low-cost fabrication of metal layers on PDMS and even on other materials of different natures including polyethylene terephthalate, paper, Si, and glass. The electrical conductivity of the PDMS/Cu electrode is comparable to that of bulk Cu. Moreover, robust bonding at the PDMS/Cu interface is evidenced by a scotch tape test and bending test of more than 20,000 cycles. Compared with previous studies using a nanosecond laser, the restriction on absorbing sensitizers could be alleviated, and catalysts could originate from precursors without polymer substrates under a femtosecond laser, which may be attributed to nonlinear absorption and ultrashort heating time with the femtosecond laser. Implementing a human-machine interface task is demonstrated by recognizing hand gestures via a multichannel electrode array with high fidelity to control a robot hand.