Lorentz force actuation of a heated atomic force microscope cantilever

Area of Science:

• Microelectromechanical systems (MEMS)
• Nanotechnology
• Materials Science

Background:

• Microcantilevers are widely used in sensing and imaging applications.
• Actuation methods for microcantilevers often involve thermal or electrostatic forces.
• Lorentz force offers an alternative actuation mechanism with unique characteristics.

Purpose of the Study:

• To investigate Lorentz force-induced actuation of a silicon microcantilever.
• To compare Lorentz force actuation with thermomechanical actuation.
• To explore applications of this actuation method in imaging and material characterization.

Main Methods:

• Integrated a resistive heater into a silicon microcantilever.
• Applied oscillating AC current through the microcantilever in a magnetic field from a NdFeB permanent magnet.
• Measured cantilever deflection and temperature rise using optical methods.
• Investigated the effect of magnetic field orientation on actuation.
• Demonstrated imaging and material softening temperature measurement using the actuated microcantilever.

Main Results:

• Achieved significant microcantilever oscillation (up to 80 nm) at resonance with low AC currents (0.2 mA).
• Lorentz force-induced deflection was substantially larger (approx. 1000 times) than thermomechanical oscillation.
• Cantilever position and magnetic field orientation influenced the deflection magnitude.
• Successfully demonstrated microcantilever-based imaging and local material softening temperature measurement.

Conclusions:

• Lorentz force provides an effective and efficient method for actuating silicon microcantilevers.
• This technique offers a significant advantage over thermomechanical actuation for microcantilever-based applications.
• The demonstrated applications highlight the potential of Lorentz force actuation for advanced imaging and material analysis.