Light-driven micromotors for on-demand and local pH sensing applications

Area of Science:

• Nanotechnology
• Chemical Engineering
• Materials Science

Background:

• Self-propelled light-driven micromotors are emerging as versatile tools for applications like cargo delivery and chemical sensing.
• Local and on-demand sensing capabilities are crucial for advanced monitoring systems.

Purpose of the Study:

• To design and demonstrate light-driven micromotors for targeted local pH sensing applications.
• To integrate multiple functionalities including light-activated propulsion, pH-dependent fluorescence, and magnetic guidance.

Main Methods:

• Fabrication of spherical Janus particles with multiple functional coatings.
• Utilizing UV light (320-400 nm) for controlled micromotor swimming.
• Employing blue light (450 nm) excitation for pH-dependent fluorescence signal emission.
• Guiding micromotor movement with a weak external uniform magnetic field (50 G).

Main Results:

• Micromotors exhibited controlled swimming under UV light and pH-dependent fluorescence.
• The fluorescence intensity change allowed for on-demand, local pH measurement.
• System optimization and calibration were performed through systematic experimental studies.
• Clear visual demarcation of large pH changes was achieved, with potential for precise measurement of small changes using spectrometers.

Conclusions:

• The developed light-driven micromotors offer an easy-to-design, light-activated platform for pH monitoring.
• Their directional swimming and on-demand local sensing capabilities show potential to revolutionize pH monitoring in diverse fields.
• Potential applications include lab-on-a-chip devices, biomedical research, environmental monitoring, and industrial quality control.