Miniature multiplexed label-free pH probe in vivo

Area of Science:

• Neuroscience
• Biomedical Engineering
• Sensor Technology

Background:

• Accurate in vivo pH measurement is crucial for understanding brain pathophysiology.
• Existing techniques lack the precision for localized pH changes in deep brain structures.
• Developing novel in vivo sensing technologies is essential for advancing neurological research.

Purpose of the Study:

• To develop an all-in-one, label-free pH probe for spatially-resolved in vivo pH sensing.
• To enable simultaneous pH measurements at multiple locations within the brain.
• To investigate the potential of this technology in capturing physiological and pathological pH fluctuations in vivo.

Main Methods:

• Utilized a light-addressable potentiometric sensor (LAPS) coupled to a flexible multimodal fiber.
• Integrated multicore optical waveguides and electrodes within the fiber for light delivery and photocurrent readout.
• Employed multi-spot simultaneous illumination with different modulation frequencies for demultiplexing photocurrent signals.
• Achieved simultaneous pH measurements at 14 pixels with 250 μm spatial resolution and 30 Hz temporal resolution.

Main Results:

• Demonstrated a pH sensitivity of 57.5 ± 2.2 mV/pH across all measurable pixels.
• Successfully implanted the probe into the rat hippocampal formation for in vivo testing.
• Validated the probe's capability to capture pH changes at multiple pixels under physiological and pathological conditions.
• Confirmed the technology represents a new class of in vivo chemical sensing for deep brain structures.

Conclusions:

• The developed all-in-one pH probe offers high spatial and temporal resolution for in vivo brain pH monitoring.
• This technology facilitates the investigation of intrinsic chemical signals in deep brain structures.
• Represents a significant advancement in in vivo chemical sensing for neuroscience research.
• Opens new avenues for understanding brain pathophysiology through precise pH fluctuation analysis.