Process development for dry etching polydimethylsiloxane for neural electrodes

Area of Science:

• Materials Science
• Biomedical Engineering
• Microfabrication

Background:

• High-density electrode arrays are crucial for advanced medical devices.
• Polydimethylsiloxane (PDMS) is a common material for flexible electronics and biomedical implants.
• Fabrication of micro-structures in PDMS presents unique challenges.

Purpose of the Study:

• To develop a reactive ion (dry) etching process for patterning micro-structures in medical-grade PDMS.
• To enable the creation of high-density electrode arrays for improved electrode-tissue interface.
• To investigate the etch performance and surface modification of PDMS.

Main Methods:

• Reactive ion etching using sulfur hexafluoride (SF(6)) and oxygen (O(2)) plasma.
• Surface analysis using profilometry, scanning electron microscopy (SEM), and atomic force microscopy (AFM).
• Chemical modification analysis via X-ray photoelectron spectroscopy (XPS).

Main Results:

• Achieved micro-structuring of PDMS using SF(6) and O(2) plasma.
• Determined a maximum etch rate of approximately 0.22 μm/min.
• Confirmed chemical modification of the PDMS surface through XPS analysis.

Conclusions:

• A viable dry etching process for PDMS microfabrication was successfully developed.
• The process allows for the creation of micro-scale openings essential for electrode-tissue interfaces.
• This technique supports the advancement of high-density electrode arrays for biomedical applications.