Optomechanical Resonating Probe for Very High Speed Sensing of Atomic Forces

TL;DR

This paper introduces a high-frequency optomechanical atomic force probe capable of ultra-high-speed sensing with sub-picometre precision, surpassing traditional AFM limitations for advanced molecular and atomic-scale investigations.

Contribution

The authors develop an optomechanical AFM probe operating at frequencies two decades higher than existing cantilevers, enabling faster, more precise atomic force spectroscopy.

Findings

Probe frequency is significantly increased, enhancing bandwidth.

Brownian motion is reduced by four orders of magnitude.

Achieved sub-picometre driven motion for high-resolution sensing.

Abstract

Atomic force spectroscopy and microscopy (AFM) are invaluable tools to characterize nanostructures and biological systems. Most experiments, including state-of-the-art images of molecular bonds, are achieved by driving probes at their mechanical resonance. This resonance reaches the MHz for the fastest AFM micro-cantilevers, with typical motion amplitude of a few nanometres. Next-generation investigations of molecular scale dynamics, including faster force imaging and higher-resolution spectroscopy of dissipative interactions, require more bandwidth and vibration amplitudes below interatomic distance, for non-perturbative short-range tip-matter interactions. Probe frequency is a key parameter to improve bandwidth while reducing Brownian motion, allowing large signal-to-noise for exquisite resolution. Optomechanical resonators reach motion detection at 10^(-18) m.(Hz)^(-1/2), while coupling light to bulk vibration modes whose frequencies largely surpass those of cantilevers. Here we introduce an optically operated resonating optomechanical atomic force probe of frequency 2 decades above the fastest functional AFM cantilevers while Brownian motion is 4 orders below. Based on a Silicon-On-Insulator technology, the probe demonstrates high-speed sensing of contact and non-contact interactions with sub-picometre driven motion, breaking open current locks for faster and finer atomic force spectroscopy.