Multisite microprobes for neural recordings

Area of Science:

• Neuroscience
• Biomedical Engineering
• Materials Science

Background:

• Simultaneous recording of neural activity is crucial for understanding complex brain functions.
• Existing technologies may have limitations in spatial resolution or longevity.
• Development of advanced neural recording tools is an ongoing area of research.

Purpose of the Study:

• To develop and characterize novel multisite, passive microprobes for simultaneous neural recording.
• To evaluate the fabrication process and performance of these microprobes.
• To demonstrate the utility of the microprobes in acute neurophysiological experiments.

Main Methods:

• Microprobes fabricated using standard integrated circuit techniques with gold electrodes and polyimide dielectric layers.
• Planar, dagger-shaped probe design with 4 or 6 recording sites (approx. 25 microns sq).
• Encapsulation of probe head with silicone RTV and epoxy for protection; impedance and lifetime testing in saline.

Main Results:

• Microprobes successfully fabricated with 4 or 6 recording sites.
• Site impedances at 1 kHz typically between 2-4 M omega.
• Probe lifetimes exceeded 750 hours in continuous saline immersion.
• Action potential activity recorded from dorsal column nuclei neurons in anesthetized rats.

Conclusions:

• Multisite, passive microprobes offer a viable method for simultaneous multi-neuron recordings.
• The fabrication process is compatible with standard integrated circuit techniques.
• The probes demonstrate sufficient performance and longevity for acute neurophysiological studies.