5×5 CMOS capacitive sensor array for detection of the neurotransmitter dopamine

Area of Science:

• Biomedical Engineering
• Nanotechnology
• Analytical Chemistry

Background:

• Accurate detection of neurotransmitters like dopamine (DA) is crucial for neurological research and diagnostics.
• Existing detection methods often lack the sensitivity or specificity required for low-concentration analysis.
• Miniaturized sensors offer potential for in-situ and real-time monitoring.

Purpose of the Study:

• To develop and validate miniaturized complementary metal oxide semiconductor (CMOS) capacitive sensors for ultra-sensitive dopamine detection.
• To enhance sensor resolution through monolithic integration and sub-micrometer electrode design.
• To assess the sensor's selectivity against interfering species.

Main Methods:

• Fabrication of a 5x5 sensor array with five distinct sub-micrometer interdigitated microelectrode designs.
• Immobilization of 4-carboxyphenylboronic acid (CPBA) as the sensing interface for dopamine binding.
• Utilizing CMOS readout circuitry for signal transduction based on capacitance changes.
• Quantifying capacitance variations due to dopamine-analyte interactions and assessing signal-to-control ratios.

Main Results:

• Achieved dopamine detection down to the sub-femtomolar (sub-fM) range.
• Demonstrated significantly enhanced sensing resolution via monolithic integration and optimized electrode geometry.
• Observed capacitance changes exceeding control groups by a factor greater than one at 0.1 fM DA concentration across all designs.
• Confirmed selectivity for dopamine over other species like tyramine.

Conclusions:

• Miniaturized CMOS capacitive sensors enable highly sensitive and selective dopamine detection at ultra-low concentrations.
• Monolithic integration and advanced microelectrode design are key to improving sensor performance.
• The developed sensors show promise for advanced neurological diagnostics and research applications.