A strategy for chemical sensing based on frequency tunable acoustic devices

Area of Science:

• Acoustic sensing
• Biosensing
• Materials science

Background:

• Traditional acoustic sensors often rely on piezoelectric materials.
• There is a need for versatile acoustic sensors that can operate in diverse conditions and with various materials.

Purpose of the Study:

• To introduce and characterize a new acoustic sensor geometry, the magnetic acoustic resonant sensor (MARS).
• To demonstrate the MARS device's capability for detecting mass loading, viscosity changes, and biomolecular interactions.

Main Methods:

• Fabrication of a resonant plate from nonpiezoelectric materials with an underside aluminum film coating.
• Induction of harmonic radial shear waves using enhanced magnetic direct generation with an rf coil and NdFeB magnet.
• Monitoring frequency changes due to mass loading, interaction with viscous fluids, and protein adsorption/binding.

Main Results:

• Achieved frequency changes of 106 Hz/nm for mass loading and detected viscosity changes as low as 0.0006 cP at 50 MHz.
• Demonstrated a detection limit of approximately 75 ng/mL for protein adsorption (human IgG).
• Observed high sensitivity to viscoelastic changes in adsorbed proteins, evidenced by binding studies with glycogen phosphorylase b.

Conclusions:

• The MARS device offers a new platform for tunable acoustic biosensing using a broad range of materials.
• The sensor's ability to generate shear waves unaffected by solution conductivity broadens its applicability.
• MARS technology shows promise for sensitive and versatile detection in various scientific and diagnostic fields.