Biosensor microprobes with integrated microfluidic channels for bi-directional neurochemical interaction.

Area of Science:

• Neuroscience
• Biomedical Engineering
• Materials Science

Background:

• Accurate detection of neurochemicals like choline is crucial for understanding brain function.
• Existing methods often lack the spatial and temporal resolution needed for in vivo brain research.
• Developing multi-functional tools for simultaneous stimulation and recording is a key challenge.

Purpose of the Study:

• To report on the development of silicon-based microprobes for selective choline detection in brain tissue.
• To integrate microfluidic channels for controlled liquid delivery alongside biosensor microelectrodes.
• To demonstrate simultaneous chemical stimulation and recording capabilities.

Main Methods:

• Fabrication of silicon microprobes using state-of-the-art micromachining.
• Coating recessed microelectrodes with an enzymatic layer for choline detection.
• Integration of microfluidic channels for local liquid delivery.
• Electrochemical adsorption for functionalization of electrodes.
• Development of a custom holder for probe interconnections and storage.

Main Results:

• Microprobes with dimensions of 8 mm length and 250 µm × 250 µm cross-section were fabricated.
• Each probe shank featured four recessed biosensor microelectrodes (50 µm × 150 µm) and up to two microfluidic channels.
• Achieved choline detection sensitivity better than 10 pA µm(-1) and a detection limit below 1 µM.
• Demonstrated a response time of 2 s for choline detection.
• Successfully performed simultaneous chemical stimulation and recording in an agarose gel-based brain phantom.

Conclusions:

• The developed silicon microprobes offer a multi-functional platform for brain research.
• The integrated biosensors and microfluidic channels allow for precise, localized chemical delivery and simultaneous recording.
• These probes provide adequate characteristics for detecting choline at physiologically relevant concentrations with high resolution.
• The fabrication and packaging methods ensure reproducibility, cost-effectiveness, and ease of use.