Suspended microchannel resonators for ultralow volume universal detection

Area of Science:

• Analytical Chemistry
• Microfluidics
• Sensor Technology

Background:

• Miniaturized total analysis systems (mu-TAS) require sensitive universal detectors for subnanoliter volumes.
• Existing detectors often lose sensitivity as detection volumes decrease.

Purpose of the Study:

• To exploit the unique scaling properties of the suspended microchannel resonator (SMR) for universal detection.
• To demonstrate high sensitivity and dynamic range at the picoliter scale.
• To showcase the SMR's potential for real-time monitoring in microfluidic systems.

Main Methods:

• Utilized the suspended microchannel resonator (SMR) for detection in a 10 pL analysis volume.
• Measured analytes including polyethylene glycol (PEG), glucose, and glycine.
• Employed gel filtration chromatography coupled with SMR detection for real-time separation monitoring.

Main Results:

• Achieved a density detection limit of approximately 1 microg/cm³ with a 10 Hz bandwidth.
• Demonstrated a dynamic range of 6 decades.
• Obtained molar detection limits of 0.66 microM for PEG 8 kDa, 13.5 microM for glucose, and 31.6 microM for glycine.
• Successfully acquired a chromatogram by measuring eluate density in real-time PEG separation.

Conclusions:

• The SMR provides universal detection with high sensitivity and a wide dynamic range at the subnanoliter scale.
• SMR is suitable for real-time monitoring in various separation techniques like chromatography and capillary electrophoresis.
• Direct integration of SMR into mu-TAS is feasible without performance compromise.