Article
Fabrication process of 3D pre-pressed PFA-based electrodes for effective stimulation
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Authors
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Jiseon Lee
- Department of Electrical and Computer Engineering, Seoul National University, Seoul, South Korea
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J. Kim
- Department of Transdisciplinary Medicine, Seoul National University Hospital, Seoul, South Korea
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N. Lee
- Department of Electrical and Computer Engineering, Seoul National University, Seoul, South Korea
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J. Seo
- Department of Electrical and Computer Engineering, Seoul National University, Seoul, South Korea; Biomedical Research Institute, Seoul National University Hospital, Seoul, South Korea
| Published: | May 9, 2025 |
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Outline
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Objective: In this study, a process of manufacturing PFA film-based electrodes in 3D form for more effective stimulation was proposed.
Materials and Methods: A 50 µm thick PFA film was sonicated in ethanol and subsequently dried. The dried film was then sandwiched between a 500 µm thick PTFE film and a 50 µm thick PTFE film, followed by pre-thermal pressing in a molded aluminum jig. The pressing was conducted at 280° C for 20 minutes, followed by slow cooling. To minimize alignment issues caused by the thermal shrinkage of the PFA film, additional weights are applied during the cooling process. Through this process, the stimulation sites were thermally molded into a plateau shape. The pre-pressed PFA film was attached to a dummy silicon wafer using resin release tape, followed by surface treatment with argon plasma. Subsequently, metal layers were deposited using an e-gun evaporator and patterned using an aligner. After electroplating and etching, the electrodes were thermally laminated with an additional site-opened bare PFA film.
Results: We fabricated PFA-based electrodes with a site protruding in the form of a plateau with a height of 150 µm. The diameter of the plateau's elevated stage is 250 µm, with a base diameter of 350 µm. The electrode includes 20 channels, and its thickness is 70 µm.
Discussion: Since the objective is to stimulate the optic nerve via the subretinal space, ex-vivo experiments will be conducted to stimulate the subretinal tissue layer and compare the stimulation efficiency of the 3D electrodes with that of planar electrodes.
Acknowledgment: This research was supported by a grant of the Korea Health Technology R&D Project through the Korea Health Industry Development Institute (KHIDI), funded by the Ministry of Health & Welfare, Republic of Korea (grant number: RS-2023-00304861).
