Integrated active mixing and biosensing using surface acoustic waves (SAW) and surface plasmon resonance (SPR) on a...

Area of Science:

• Biosensing
• Microfluidics
• Acoustic Actuation

Background:

• Surface plasmon resonance (SPR) is a label-free optical sensing technique.
• Surface acoustic wave (SAW) devices offer precise microfluidic manipulation.
• Integrating SPR sensing and SAW actuation on a single substrate is challenging.

Purpose of the Study:

• To develop an integrated SPR sensing and SAW actuation device on a lithium niobate substrate.
• To investigate the use of SAW for active microfluidic mixing to enhance SPR-based assays.
• To evaluate the performance and potential of this integrated system for lab-on-chip applications.

Main Methods:

• Fabrication of a device combining SPR sensing and Rayleigh-type SAW actuation on a LiNbO(3) substrate.
• Utilizing SAW to induce microfluidic mixing in the fluid layer above the SPR sensor.
• Performing avidin-biotin binding assays to validate the accelerated kinetics and assess parasitic effects.

Main Results:

• SAW-induced microfluidic mixing significantly accelerated the binding kinetics of the avidin-biotin assay.
• A parasitic SPR response due to SAW-induced heating was observed but dissipated quickly.
• The parasitic effect did not impact the overall assay response due to a brief relaxation time.
• Simultaneous fabrication of SPR and SAW components is feasible using low-cost microfabrication.

Conclusions:

• The integrated SPR-SAW device effectively enhances microfluidic mixing and assay kinetics.
• The system demonstrates robustness against SAW-induced thermal effects.
• This technology is highly suitable for developing advanced lab-on-chip devices.