Carbon fiber on polyimide ultra-microelectrodes.

Area of Science:

• Neuroscience
• Materials Science
• Biomedical Engineering

Background:

• Conventional neural recording electrodes degrade due to insertion trauma and tissue response, limiting recording longevity.
• Electrode size, stiffness, and material biocompatibility influence tissue reactivity and device failure.
• Existing carbon fiber arrays have limited channel density due to fabrication and interconnect challenges.

Purpose of the Study:

• To develop an improved fabrication method for flexible carbon fiber ultra-microelectrode arrays.
• To enable high-density neural recording and stimulation arrays with enhanced longevity.
• To facilitate a transition towards automated manufacturing of neural probes.

Main Methods:

• Carbon fibers were precisely aligned using a 3D-printed tool with sub-micron resolution.
• Electrical connections were established via indium deposition and low-temperature microsoldering to a polyimide substrate.
• Iridium oxide films were electrodeposited to enhance the charge injection capacity of the carbon fibers.

Main Results:

• Successful recording of spontaneous multiunit activity and stimulation-evoked responses from a small peripheral nerve (SNR > 10 and > 120, respectively).
• Demonstrated the utility of the fabricated carbon fiber arrays for both neural recording and electrical stimulation.
• Achieved improved charge injection capacity through iridium oxide electrodeposition.

Conclusions:

• The developed fabrication technique allows for further miniaturization of carbon fiber ultra-microelectrode arrays.
• These advances are crucial for creating high-density neural probes with improved longevity and functionality.
• The method supports a move towards automated manufacturing processes for neural recording devices.