Chemical Sensing Using Thermocouple Cantilevers: Pushing Toward Quantum Sensing

Le résumé fourni par la source

Detecting and quantifying minuscule quantities of chemicals with high molecular selectivity remains a measurement challenge. We present a photothermal spectroscopic method that exploits the Seebeck effect in a finely engineered nanoscale thermocouple junction at the apex of a microcantilever. The temperature variations driving this thermoelectric effect are induced by the nonradiative decay of molecular adsorbates, efficiently excited by a tunable infrared source. This approach not only benefits from an extremely small thermal mass and superior thermal insulation but also achieves an atto-gram detection limit. The simplicity and compactness of its electronic readout further enhance the method's applicability. In this work, we demonstrate the detection of photothermal spectra for physisorbed trinitrotoluene (TNT) and dimethyl methylphosphonate (DMMP) molecules, as well as representative polymers, with estimated masses as small as 10-18 grams. Our findings underscore the potential of classical measurement techniques to approach the sensitivity and selectivity limits required for molecular detection. Establishing such classical limits is an important part of transitioning into the quantum-sensing regime, which aims to explore new enhancements in sensitivity and selectivity in chemical sensing beyond the conventional limits.

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