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

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 × 2 mm2 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 104 in air and up to 4 × 104 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.

Polymer Patterning with Self-Heating Atomic Force Microscope Probes.

Scanning probe-assisted patterning methods already demonstrated a high degree of capabilities on submicrometer scales. However, the throughput is still far from its potential because of complexity or fragility of the probes for exploiting thermal effects, chemical reactions, and voltage-induced processes in various patterning operations. Here, we present a new approach to thermomechanical patterning by implementing a multitasking atomic force microscopy (AFM) probe: the functionalized planar probes. In this method, we can generate a tunable thermal gradient between the tip and the sample, wherein they remain in the noncontact regime. In principle, the capillary instability provoked by the van der Waals interaction yields a pull-off force toward the tip. Hence, locally rising protrusions form features at any selected position on a polymer surface without any chemical reaction or irreversible transformation. These multitasking probe-integrated AFMs can pave the way for a remarkable freedom in determining the operation regime on submicrometer surface-patterning applications.