Enhancing sensitivity in atomic force microscopy for planar tip-on-chip probes

TL;DR

This paper introduces a novel method to enhance the sensitivity of atomic force microscopy by rebalancing and reconfiguring tuning fork-based sensors for use with large, chip-like probes, significantly improving performance.

Contribution

The authors developed a new approach involving tuning fork rebalancing, improved holder fixation, and electrode reconfiguration to restore high sensitivity in AFM with chip-like probes.

Findings

Achieved high Q-factors up to 10E4 in air and 4x10E4 in vacuum.

Reduced energy dissipation through soft wire mounting.

Enabled electrical access without compromising force sensing.

Abstract

We present a new approach to tuning fork-based atomic force microscopy for utilizing advanced "tip-on-chip" probes with high sensitivity and broad compatibility. Usually, such chip-like probes with a size reaching 2 mm x 2 mm drastically perturb the oscillation of the tuning fork, resulting in poor performance in its intrinsic force sensing. Therefore, restoring initial oscillatory characteristics is necessary for regaining high sensitivity. To this end, we developed a new approach consisting of three basic steps: tuning fork rebalancing, revamping holder-sensor fixation, and electrode reconfiguration. Mass rebalancing allows the tuning fork to recover the frequency and regain high Q-factor values up to 10E4 in air and up to 4 x 10E4 in ultra-high vacuum conditions. The floating-like holder-fixation using soft wires significantly reduces energy dissipation from the mounting elements. Combined with the soft wires, reconfigured electrodes provide electrical access to the chip-like probe without intervening in the force-sensing signal. Finally, our easy-to-implement approach allows converting the atomic force microscopy-tip from a passive tool to a dedicated microdevice with extended functionality.