Silver/silver chloride microneedles can detect penetration through the round window membrane

Area of Science:

• Biomedical Engineering
• Materials Science
• Electrochemical Sensors

Background:

• Microperforations in the round window membrane (RWM) enhance therapeutic delivery to the inner ear.
• Current methods lack reliable detection of microneedle penetration through the RWM.
• Precise detection of microneedle entry is crucial for accurate drug delivery.

Purpose of the Study:

• To explore electrochemical detection for identifying the precise moment of microneedle penetration of semi-permeable membranes.
• To validate the use of silver-plated microneedles for detecting RWM perforation.
• To assess the correlation between saline concentration and voltage change during membrane penetration.

Main Methods:

• Stainless steel microneedles were electroplated with silver to create Ag/AgCl coatings.
• A Franz cell diffusion system with varying saline concentrations and artificial perilymph was used.
• Continuous voltage measurements were recorded during microneedle penetration of a synthetic membrane.

Main Results:

• Silver-plated microneedles detected an instantaneous voltage change upon traversing the membrane.
• The magnitude of voltage change increased with higher saline concentrations.
• Voltage detection was stable and reliable across multiple trials.

Conclusions:

• Ag/AgCl coated microneedles effectively detect penetration across semi-permeable membranes.
• This electrochemical approach provides a reliable method for confirming microneedle entry.
• The findings support the use of this technique for precise therapeutic delivery via microneedles.