Monolayer-functionalized microfluidics devices for optical sensing of acidity

Area of Science:

• Microfluidics
• Opto-chemosensors
• Chemical Sensing

Background:

• Microfluidic devices offer precise control over small fluid volumes.
• Opto-chemosensors require integration into microfluidic platforms for advanced analysis.
• Fluorescent molecules can be utilized as indicators for chemical properties like pH.

Purpose of the Study:

• To develop and demonstrate opto-chemosensors integrated within microfluidics networks.
• To utilize surface-immobilized fluorescent molecules as pH-sensitive switches.
• To enable real-time monitoring of chemical environments in microfluidic systems.

Main Methods:

• Coating microfluidic channel surfaces with self-assembled monolayers.
• Binding fluorescent sensing molecules (Rhodamine B, Oregon Green derivative) to the monolayer.
• Utilizing reversible fluorescence changes in response to pH variations.
• Implementing systems in glass microchannels and hybrid glass/PDMS channels.

Main Results:

• Demonstrated reversible switching between fluorescent and non-fluorescent states of Rhodamine B based on acidity.
• Successfully monitored the mixing of solutions with different pH levels in microchannels.
• Showcased a correlation between fluorescence intensity and pH in aqueous solutions using an Oregon Green derivative.
• Validated the potential for real-time pH sensing in microfluidic systems.

Conclusions:

• Opto-chemosensor integration in microfluidics is feasible using surface functionalization.
• Fluorescent molecular switches provide a viable method for pH sensing in microfluidic networks.
• These systems facilitate rapid, reproducible analysis of minimal sample volumes.