Electrochemical and biological performance of hierarchical platinum-iridium electrodes structured by a femtosecond laser

Linze Li; Changqing Jiang; Wanru Duan; Zhiyan Wang; Feng Zhang; Changgeng He; Tiangang Long; Luming Li

doi:10.1038/s41378-022-00433-8

Electrochemical and biological performance of hierarchical platinum-iridium electrodes structured by a femtosecond laser

Microsyst Nanoeng. 2022 Sep 2:8:96. doi: 10.1038/s41378-022-00433-8. eCollection 2022.

Authors

Linze Li^{1

2}, Changqing Jiang¹, Wanru Duan^{3

4}, Zhiyan Wang¹, Feng Zhang¹, Changgeng He¹, Tiangang Long¹, Luming Li^{1

5

6

7}

Affiliations

¹ National Engineering Research Center of Neuromodulation, School of Aerospace Engineering, Tsinghua University, Beijing, 100084 China.
² School of Mechanical Engineering and Automation, Fuzhou University, Fuzhou, 350108 China.
³ Department of Neurosurgery, China International Neuroscience Institute (CHINA-INI), Xuanwu Hospital, Capital Medical University, Beijing, 100053 China.
⁴ Lab of Spinal Cord Injury and Functional Reconstruction, China International Neuroscience Institute (CHINA-INI), Xuanwu Hospital, Capital Medical University, Beijing, 100053 China.
⁵ Precision Medicine & Healthcare Research Center, Tsinghua-Berkeley Shenzhen Institute, Tsinghua University, Shenzhen, 518071 China.
⁶ IDG/McGovern Institute for Brain Research at Tsinghua University, Beijing, 100084 China.
⁷ Institute of Epilepsy, Beijing Institute for Brain Disorders, Beijing, 100093 China.

Abstract

Neural electrode interfaces are essential to the stimulation safety and recording quality of various bioelectronic therapies. The recently proposed hierarchical platinum-iridium (Pt-Ir) electrodes produced by femtosecond lasers have exhibited superior electrochemical performance in vitro, but their in vivo performance is still unclear. In this study, we explored the electrochemical performance, biological response, and tissue adhesion of hierarchical Pt-Ir electrodes by implantation in adult rat brains for 1, 8, and 16 weeks. Regular smooth Pt-Ir electrodes were used as a control. The results showed that the electrochemical performance of both electrodes decreased and leveled off during implantation. However, after 16 weeks, the charge storage capacity of hierarchical electrodes stabilized at ~16.8 mC/cm², which was 15 times that of the smooth control electrodes (1.1 mC/cm²). Moreover, the highly structured electrodes had lower impedance amplitude and cutoff frequency values. The similar histological response to smooth electrodes indicated good biocompatibility of the hierarchically structured Pt-Ir electrodes. Given their superior in vivo performance, the femtosecond laser-treated Pt-Ir electrode showed great potential for neuromodulation applications.

Keywords: Electrical and electronic engineering; Nanostructures.