CMOS-Based Implantable Multi-Ion Image Sensor for Mg²⁺ Measurement in the Brain

Area of Science:

• Neuroscience
• Biomedical Engineering
• Sensor Technology

Background:

• Extracellular magnesium ion (Mg²⁺) and calcium ion (Ca²⁺) concentrations are critical in brain function.
• Existing sensors often lack the selectivity required for accurate, simultaneous measurement of these ions.

Purpose of the Study:

• To develop and evaluate an implantable multi-ion image sensor for selective extracellular Mg²⁺ and Ca²⁺ measurement in the brain.
• To overcome the challenge of low selectivity in Mg²⁺-sensitive membranes for Ca²⁺.

Main Methods:

• Fabrication of a Complementary Metal Oxide Semiconductor (CMOS)-based potentiometric sensor array.
• Co-deposition of Mg²⁺-sensitive and Ca²⁺-sensitive membranes on the sensor array.
• Characterization of sensor sensitivity to Mg²⁺ and Ca²⁺.
• Validation experiments with varying ion concentrations.

Main Results:

• The sensor demonstrated selective measurement capabilities for both Mg²⁺ and Ca²⁺.
• Characterization confirmed Ca²⁺ sensitivity of 26.5 mV/dec and Mg²⁺ sensitivity of 19 mV/dec.
• Successful real-time imaging and quantification of extracellular Mg²⁺ and Ca²⁺ concentration changes were achieved.

Conclusions:

• The developed implantable sensor enables selective and simultaneous extracellular multi-ion imaging of Mg²⁺ and Ca²⁺ in the brain.
• This technology holds promise for advancing research into brain function and neurological disorders.